Hans Kristian Kamfjord Eriksen

• Banday, A. J.; Gimeno-Amo, C.; Diego-Palazuelos, P.; Hoz, E. de la; Gruppuso, A. & Raffuzzi, N. [Vis alle 104 forfattere av denne artikkelen] (2026). LiteBIRD science goals and forecasts. E-mode anomalies. Journal of Cosmology and Astroparticle Physics (JCAP). 2026(1). doi: 10.1088/1475-7516/2026/01/036. Fulltekst i vitenarkiv Vis sammendrag

  Various so-called anomalies have been found in both the WMAP and Planck cosmic microwave background (CMB) temperature data that exert a mild tension against the highly successful best-fit 6 parameter cosmological model, potentially providing hints of new physics to be explored. That these are real features on the sky is uncontested. However, given their modest significance, whether they are indicative of true departures from the standard cosmology or simply statistical excursions due to a mildly unusual configuration of temperature anisotropies on the sky which we refer to as the “fluke hypothesis” cannot be addressed further without new information. No theoretical model of primordial perturbations has to date been constructed that can explain all of the temperature anomalies. Therefore, we focus in this paper on testing the fluke hypothesis, based on the partial correlation between the temperature and E-mode CMB polarisation signal. In particular, we compare the properties of specific statistics in polarisation, built from unconstrained realisations of the ΛCDM cosmological model as might be observed by the LiteBIRD satellite, with those determined from constrained simulations, where the part of the E-mode anisotropy correlated with temperature is constrained by observations of the latter. Specifically, we use inpainted Planck 2018 SMICA temperature data to constrain the E-mode realisations. Subsequent analysis makes use of masks defined to minimise the impact of the inpainting procedure on the E-mode map statistics. We find that statistical assessments of the E-mode data alone do not provide any evidence for or against the fluke hypothesis. However, tests based on cross-statistical measures determined from temperature and E modes can allow this hypothesis to be rejected with a moderate level of probability.

• Ruiz-Granda, M.; Diego-Palazuelos, P.; Gimeno-Amo, C.; Vielva, P.; Lonappan, A.I. & Namikawa, T. [Vis alle 105 forfattere av denne artikkelen] (2025). LiteBIRD science goals and forecasts: improved full-sky reconstruction of the gravitational lensing potential through the combination of Planck and LiteBIRD data. Journal of Cosmology and Astroparticle Physics (JCAP). 2025(11). doi: 10.1088/1475-7516/2025/11/073. Fulltekst i vitenarkiv Vis sammendrag

  Cosmic microwave background (CMB) photons are deflected by large-scale structure through gravitational lensing. This secondary effect introduces higher-order correlations in CMB anisotropies, which are used to reconstruct lensing deflections. This allows mapping of the integrated matter distribution along the line of sight, probing the growth of structure, and recovering an undistorted view of the last-scattering surface. Gravitational lensing has been measured by previous CMB experiments, with Planck 's 42 σ detection being the current best full-sky lensing map. We present an enhanced LiteBIRD lensing map by extending the CMB multipole range and including the minimum-variance estimation, leading to a 49 to 58 σ detection over 80 % of the sky, depending on the final complexity of polarized Galactic emission. The combination of Planck and LiteBIRD will be the best full-sky lensing map in the 2030s, providing a 72 to 78 σ detection over 80 % of the sky, almost doubling Planck 's sensitivity. Finally, we explore different applications of the lensing map, including cosmological parameter estimation using a lensing-only likelihood and internal delensing, showing that the combination of both experiments leads to improved constraints. The combination of Planck + LiteBIRD will improve the S 8 constraint by a factor of 2 compared to Planck , and Planck + LiteBIRD internal delensing will improve LiteBIRD 's tensor-to-scalar ratio constraint by 6 %. We have tested the robustness of our results against foreground models of different complexity, showing that improvements remain even for the most complex foregrounds.

• Bortolami, M.; Raffuzzi, N.; Pagano, L.; Puglisi, G.; Anand, A. & Banday, A.J. [Vis alle 110 forfattere av denne artikkelen] (2025). First release of LiteBIRD simulations from an end-to-end pipeline. Journal of Cosmology and Astroparticle Physics (JCAP). 2025(11). doi: 10.1088/1475-7516/2025/11/042. Fulltekst i vitenarkiv Vis sammendrag

  The LiteBIRD satellite mission aims at detecting Cosmic Microwave Background B modes with unprecedented precision, targeting a total error on the tensor-to-scalar ratio r of δr ∼ 0.001. Operating from the L2 Lagrangian point of the Sun-Earth system, LiteBIRD will survey the full sky across 15 frequency bands (34 to 448 GHz) for 3 years.The current LiteBIRD baseline configuration employs 4508 detectors sampling at 19.1 Hz to achieve an effective polarization sensitivity of 2 μK arcmin and an angular resolution of 31 arcmin (at 140 GHz). We describe the first release of the official LiteBIRD simulations, realized with a new simulation pipeline developed using the LiteBIRD Simulation Framework. This pipeline generates 500 full-sky simulated maps at a HEALPix resolution of Nside=512. The simulations include also one year of Time Ordered Data (TOD) for approximately one-third of LiteBIRD's total detectors.

• Aurvik, Ragnhild; Galloway, Mathew; Gjerløw, Eirik; Fuskeland, Unni; Basyrov, Artem & Bortolami, M. [Vis alle 110 forfattere av denne artikkelen] (2025). On the computational feasibility of Bayesian end-to-end analysis of LiteBIRD simulations within Cosmoglobe. Journal of Cosmology and Astroparticle Physics (JCAP). 2025(11). doi: 10.1088/1475-7516/2025/11/041. Fulltekst i vitenarkiv Vis sammendrag

  We assess the computational feasibility of end-to-end Bayesian analysis of the JAXA-led LiteBIRD experiment by analysing simulated time ordered data (TOD) for a subset of detectors through the Cosmoglobe and Commander3 framework. The data volume for the simulated TOD is 1.55 TB, or 470 GB after Huffman compression. From this we estimate a total data volume of 238 TB for the full three year mission, or 70 TB after Huffman compression. We further estimate the running time for one Gibbs sample, from TOD to cosmological parameters, to be approximately 3000 CPU hours. The current simulations are based on an ideal instrument model, only including correlated 1/ f noise. Future work will consider realistic systematics with full end-to-end error propagation. We conclude that these requirements are well within capabilities of future high-performance computing systems.

• Tomasi, M.; Pagano, L.; Anand, A.; Baccigalupi, C.; Banday, A.J. & Bortolami, M. [Vis alle 114 forfattere av denne artikkelen] (2025). A simulation framework for the LiteBIRD instruments. Journal of Cosmology and Astroparticle Physics (JCAP). 2025(11). doi: 10.1088/1475-7516/2025/11/040. Fulltekst i vitenarkiv Vis sammendrag

  LiteBIRD , the Lite (Light) satellite for the study of B-mode polarization and Inflation from cosmic background Radiation Detection, is a space mission focused on primordial cosmology and fundamental physics. In this paper, we present the LiteBIRD Simulation Framework (LBS), a Python package designed for the implementation of pipelines that model the outputs of the data acquisition process from the three instruments on the LiteBIRD spacecraft: LFT (Low-Frequency Telescope), MFT (Mid-Frequency Telescope), and HFT (High-Frequency Telescope). LBS provides several modules to simulate the scanning strategy of the telescopes, the measurement of realistic polarized radiation coming from the sky (including the Cosmic Microwave Background itself, the Solar and Kinematic dipole, and the diffuse foregrounds emitted by the Galaxy), the generation of instrumental noise and the effect of systematic errors, like pointing wobbling, non-idealities in the Half-Wave Plate, et cetera . Additionally, we present the implementation of a simple but complete pipeline that showcases the main features of LBS. We also discuss how we ensured that LBS lets people develop pipelines whose results are accurate and reproducible. A full end-to-end pipeline has been developed using LBS to characterize the scientific performance of the LiteBIRD experiment. This pipeline and the results of the first simulation run are presented in Puglisi et al. (2025).

• Hoz, E. de la; Diego-Palazuelos, P.; Errard, J.; Gruppuso, A.; Jost, B. & Sullivan, Raelyn [Vis alle 115 forfattere av denne artikkelen] (2025). LiteBIRD science goals and forecasts: constraining isotropic cosmic birefringence. Journal of Cosmology and Astroparticle Physics (JCAP). 2025(7). doi: 10.1088/1475-7516/2025/07/083. Fulltekst i vitenarkiv Vis sammendrag

  Cosmic birefringence (CB) is the rotation of the photons' linear polarisation plane during propagation. Such an effect is a tracer of parity-violating extensions of standard electromagnetism and would probe the existence of a new cosmological field acting as dark matter or dark energy. It has become customary to employ cosmic microwave background (CMB) polarised data to probe such a phenomenon. Recent analyses on Planck and WMAP data provide a hint of detection of the isotropic CB angle with an amplitude of around 0.3° at the level of 2.4 to 3.6σ. In this work, we explore the LiteBIRD capabilities in constraining such an effect, accounting for the impact of the more relevant systematic effects, namely foreground emission and instrumental polarisation angles. We build five semi-independent pipelines and test these against four different simulation sets with increasing complexity in terms of non-idealities. All the pipelines are shown to be robust and capable of returning the expected values of the CB angle within statistical fluctuations for all the cases considered. We find that the uncertainties in the CB estimates increase with more complex simulations. However, the trend is less pronounced for pipelines that account for the instrumental polarisation angles. For the most complex case analysed, we find that LiteBIRD will be able to detect a CB angle of 0.3° with a statistical significance ranging from 5 to 13σ, depending on the pipeline employed, where the latter uncertainty corresponds to a total error budget of the order of 0.02°.

• Ade, P.A.R.; Amiri, M.; Benton, S.J.; Bergman, A.S.; Bihary, R. & Bock, J.J. [Vis alle 69 forfattere av denne artikkelen] (2025). Analysis of Polarized Dust Emission Using Data from the First Flight of SPIDER. The Astrophysical Journal (ApJ). ISSN 0004-637X. 978(2). doi: 10.3847/1538-4357/ad900c. Fulltekst i vitenarkiv Vis sammendrag

  Using data from the first flight of Spider and from the Planck High Frequency Instrument, we probe the properties of polarized emission from interstellar dust in the Spider observing region. Component-separation algorithms operating in both the spatial and harmonic domains are applied to probe their consistency and to quantify modeling errors associated with their assumptions. Analyses of diffuse Galactic dust emission spanning the full Spider region demonstrate (i) a spectral energy distribution that is broadly consistent with a modified-blackbody (MBB) model with a spectral index of βd = 1.45 ± 0.05 (1.47 ± 0.06) for E (B)-mode polarization, slightly lower than that reported by Planck for the full sky; (ii) an angular power spectrum broadly consistent with a power law; and (iii) no significant detection of line-of-sight polarization decorrelation. Tests of several modeling uncertainties find only a modest impact (∼10% in σr) on Spider's sensitivity to the cosmological tensor-to-scalar ratio. The size of the Spider region further allows for a statistically meaningful analysis of the variation in foreground properties within it. Assuming a fixed dust temperature Td = 19.6 K, an analysis of two independent subregions of that field results in inferred values of βd = 1.52 ± 0.06 and βd = 1.09 ± 0.09, which are inconsistent at the 3.9σ level. Furthermore, a joint analysis of Spider and Planck 217 and 353 GHz data within one subregion is inconsistent with a simple MBB at more than 3σ, assuming a common morphology of polarized dust emission over the full range of frequencies. This evidence of variation may inform the component-separation approaches of future cosmic microwave background polarization experiments.

• Remazeilles, M.; Douspis, M.; Rubiño-Martín, J.A.; Banday, A.J.; Chluba, J. & Bernardis, P. de [Vis alle 107 forfattere av denne artikkelen] (2024). LiteBIRD science goals and forecasts. Mapping the hot gas in the Universe. Journal of Cosmology and Astroparticle Physics (JCAP). 2024(12). doi: 10.1088/1475-7516/2024/12/026. Fulltekst i vitenarkiv Vis sammendrag

  We assess the capabilities of the LiteBIRD mission to map the hot gas distribution in the Universe through the thermal Sunyaev-Zeldovich (SZ) effect. Our analysis relies on comprehensive simulations incorporating various sources of Galactic and extragalactic foreground emission, while accounting for the specific instrumental characteristics of the LiteBIRDmission, such as detector sensitivities, frequency-dependent beam convolution, inhomogeneous sky scanning, and 1/f noise. We implement a tailored component-separation pipeline to map the thermal SZ Compton y-parameter over 98% of the sky. Despite lower angular resolution for galaxy cluster science, LiteBIRD provides full-sky coverage and, compared to the Plancksatellite, enhanced sensitivity, as well as more frequency bands to enable the construction of an all-sky thermal SZ y-map, with reduced foreground contamination at large and intermediate angular scales. By combining LiteBIRD and Planck channels in the component-separation pipeline, we also obtain an optimal y-map that leverages the advantages of both experiments, with the higher angular resolution of the Planck channels enabling the recovery of compact clusters beyond the LiteBIRD beam limitations, and the numerous sensitive LiteBIRD channels further mitigating foregrounds. The added value ofLiteBIRD is highlighted through the examination of maps, power spectra, and one-point statistics of the various sky components. After component separation, the 1/f noise fromLiteBIRD's intensity channels is effectively mitigated below the level of the thermal SZ signal at all multipoles. Cosmological constraints on S8 = σ8 (Ωm/0.3)0.5 obtained from the LiteBIRD-Planck combined y-map power spectrum exhibits a 15 % reduction in uncertainty compared to constraints derived fromPlanck alone. This improvement can be attributed to the increased portion of uncontaminated sky available in the LiteBIRD-Planck combined y-map.

• Stutzer, Nils-Ole; Lunde, Jonas Gahr Sturtzel; Breysse, P.C.; Chung, D.T.; Cleary, K.A. & Dunne, D.A. [Vis alle 27 forfattere av denne artikkelen] (2024). COMAP Pathfinder – Season 2 results: II. Updated constraints on the CO(1–0) power spectrum. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 691. doi: 10.1051/0004-6361/202451123. Fulltekst i vitenarkiv Vis sammendrag

  We present updated constraints on the cosmological 3D power spectrum of carbon monoxide CO(1–0) emission in the redshift range 2.4–3.4. The constraints are derived from the two first seasons of Carbon monOxide Mapping Array Project (COMAP) Pathfinder line intensity mapping observations aiming to trace star formation during the epoch of galaxy assembly. These results improve on the previous Early Science results through both increased data volume and an improved data processing methodology. On the methodological side, we now perform cross-correlations between groups of detectors (“feed groups”), as opposed to cross-correlations between single feeds, and this new feed group pseudo power spectrum (FGPXS) is constructed to be more robust against systematic effects. In terms of data volume, the effective mapping speed is significantly increased due to an improved observational strategy as well as a better data selection methodology. The updated spherically and field-averaged FGPXS, C~(k), is consistent with zero, at a probability-to-exceed of around 34%, with an excess of 2.7 σ in the most sensitive bin. Our power spectrum estimate is about an order of magnitude more sensitive in our six deepest bins across 0.09 Mpc−1 < k < 0.73 Mpc−1, compared to the feed-feed pseudo power spectrum (FPXS) of COMAP ES. Each of these bins individually constrains the CO power spectrum to k PCO(k) < 2400–4900 μK2Mpc2 at 95% confidence. To monitor potential contamination from residual systematic effects, we analyzed a set of 312 difference-map null tests and found that these are consistent with the instrumental noise prediction. In sum, these results provide the strongest direct constraints on the cosmological 3D CO(1–0) power spectrum published to date.

• Harper, Stuart E.; Dickinson, Clive; Cleary, Kieran A.; Hensley, Brandon S.; Hoerning, Gabriel A. & Paladini, Roberta [Vis alle 18 forfattere av denne artikkelen] (2024). COMAP Galactic science I: observations of spinning dust emission at 30 GHz in dark clouds surrounding the λ-Orionis H II region. Monthly notices of the Royal Astronomical Society. ISSN 0035-8711. 536(3), s. 2914–2935. doi: 10.1093/mnras/stae2749. Fulltekst i vitenarkiv
• Ghigna, T.; Adler, A.; Aizawa, K.; Akamutsu, H.; Akizawa, R. & Allys, E. [Vis alle 157 forfattere av denne artikkelen] (2024). The LiteBIRD mission to explore cosmic inflation. Proceedings of SPIE, the International Society for Optical Engineering. ISSN 0277-786X. 13092. doi: 10.1117/12.3021377. Fulltekst i vitenarkiv Vis sammendrag

  LiteBIRD, the next-generation cosmic microwave background (CMB) experiment, aims for a launch in Japan’s fiscal year 2032, marking a major advancement in the exploration of primordial cosmology and fundamental physics. Orbiting the Sun-Earth Lagrangian point L2, this JAXA-led strategic L-class mission will conduct a comprehensive mapping of the CMB polarization across the entire sky. During its 3-year mission, LiteBIRD will employ three telescopes within 15 unique frequency bands (ranging from 34 through 448 GHz), targeting a sensitivity of 2.2 μK-arcmin and a resolution of 0.5° at 100 GHz. Its primary goal is to measure the tensor-toscalar ratio r with an uncertainty δr = 0.001, including systematic errors and margin. If r ≥ 0.01, LiteBIRD expects to achieve a > 5σ detection in the ℓ = 2–10 and ℓ = 11–200 ranges separately, providing crucial insight into the early Universe. We describe LiteBIRD’s scientific objectives, the application of systems engineering to mission requirements, the anticipated scientific impact, and the operations and scanning strategies vital to minimizing systematic effects. We will also highlight LiteBIRD’s synergies with concurrent CMB projects.

• Maharana, Siddharth; Ramaprakash, A.N.; Rajarshi, Chaitanya; Khodade, Pravin; Joshi, Bhushan & Chordia, Pravin [Vis alle 31 forfattere av denne artikkelen] (2024). Systems design, assembly, integration, and lab testing of WALOP-South Polarimeter. Proceedings of SPIE, the International Society for Optical Engineering. ISSN 0277-786X. 13096. doi: 10.1117/12.3016144. Fulltekst i vitenarkiv Vis sammendrag

  Wide-Area Linear Optical Polarimeter (WALOP)-South is the first wide-field and survey-capacity polarimeter in the optical wavelengths. On schedule for commissioning in 2024, it will be mounted on the 1 m SAAO telescope in Sutherland Observatory, South Africa to undertake the PASIPHAE sky survey. PASIPHAE program will create the first polarimetric sky map in the optical wavelengths, spanning more than 2000 square degrees of the southern Galactic region. In a single exposure, WALOP-South’s innovative design will enable it to measure the linear polarization (Stokes parameters q and u) of all sources in a field of view (FoV) of 35 × 35 arc-minutes-squared in the SDSS-r broadband and narrowband filters between 500-750 nm with 0.1 % polarization accuracy. The unique goals of the instrument place very stringent systems engineering goals, including on the performance of the optical, polarimetric, optomechanical, and electronic subsystems. In particular, the major technical hurdles for the project included the development of: (a) an optical design to achieve imaging quality PSFs across the FoV, (b) an optomechanical design to obtain high accuracy optical alignment in conjugation with minimal instrument flexure and stress birefringence on optics (which can lead to variable instrumental polarization), and (c) an on-sky calibration routine to remove the strong polarimetric cross-talk induced instrumental polarization to obtain 0.1% across the FoV. All the subsystems have been designed carefully to meet the overall instrument performance goals. As of May 2024, all the instrument optical and mechanical subsystems have been assembled and are currently getting tested and integrated. The complete testing and characterization of the instrument in the lab is expected to be completed by August 2024. While the instrument was initially scheduled for commissioning in 2022, it got delayed due to various technical challenges; WALOP-South is now on schedule for commissioning in second half of 2024. In this paper, we will present (a) the design and development of the entire instrument and its major subsystems, focusing the instrument’s opto-mechanical design which has not been reported before, and (b) assembly and integration of the instrument in the lab and early results from lab characterization of the instrument’s optical performance.

• Pelgrims, V.; Mandarakas, N.; Skalidis, R.; Tassis, K.; Panopoulou, G.V. & Pavlidou, V. [Vis alle 24 forfattere av denne artikkelen] (2024). The first degree-scale starlight-polarization-based tomography map of the magnetized interstellar medium. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 684. doi: 10.1051/0004-6361/202349015. Fulltekst i vitenarkiv Vis sammendrag

  We present the first degree-scale tomography map of the dusty magnetized interstellar medium (ISM) from stellar polarimetry and distance measurements. We used the RoboPol polarimeter at Skinakas Observatory to conduct a survey of the polarization of starlight in a region of the sky of about four square degrees. We propose a Bayesian method to decompose the stellar-polarization source field along the distance to invert the three-dimensional (3D) volume occupied by the observed stars. We used this method to obtain the first 3D map of the dusty magnetized ISM. Specifically, we produced a tomography map of the orientation of the plane-of-sky component of the magnetic field threading the diffuse, dusty regions responsible for the stellar polarization. For the targeted region centered on Galactic coordinates (l, b) ≈ (103.3°, 22.3°), we identified several ISM clouds. Most of the lines of sight intersect more than one cloud. A very nearby component was detected in the foreground of a dominant component from which most of the polarization signal comes and which we identified as being an intersection of the wall of the Local Bubble and the Cepheus Flare. Farther clouds, with a distance of up to 2 kpc, were similarly detected. Some of them likely correspond to intermediate-velocity clouds seen in H I spectra in this region of the sky. We found that the orientation of the plane-of-sky component of the magnetic field changes along distance for most of the lines of sight. Our study demonstrates that starlight polarization data coupled to distance measures have the power to reveal the great complexity of the dusty magnetized ISM in 3D and, in particular, to provide local measurements of the plane-of-sky component of the magnetic field in dusty regions. This demonstrates that the inversion of large data volumes, as expected from the PASIPHAE survey, will provide the necessary means to move forward in the modeling of the Galactic magnetic field and of the dusty magnetized ISM as a contaminant in observations of the cosmic microwave background polarization.

• Chung, D.T.; Breysse, P.C.; Cleary, K.A.; Dunne, D.A.; Lunde, Jonas Gahr Sturtzel & Padmanabhan, H. [Vis alle 27 forfattere av denne artikkelen] (2024). COMAP Pathfinder – Season 2 results: III. Implications for cosmic molecular gas content at z ∼ 3. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 691. doi: 10.1051/0004-6361/202451122. Fulltekst i vitenarkiv Vis sammendrag

  The Carbon monOxide Mapping Array Project (COMAP) Pathfinder survey continues to demonstrate the feasibility of line-intensity mapping using high-redshift carbon monoxide (CO) line emission traced at cosmological scales. The latest COMAP Pathfinder power spectrum analysis is based on observations through the end of Season 2, covering the first three years of Pathfinder operations. We use our latest constraints on the CO(1–0) line-intensity power spectrum at z ~ 3 to update corresponding constraints on the cosmological clustering of CO line emission and thus the cosmic molecular gas content at a key epoch of galaxy assembly. We first mirror the COMAP Early Science interpretation, considering how Season 2 results translate to limits on the shot noise power of CO fluctuations and the bias of CO emission as a tracer of the underlying dark matter distribution. The COMAP Season 2 results place the most stringent limits on the CO tracer bias to date, at ⟨T b⟩ < 4.8 μK, which translates to a molecular gas density upper limit of ρH2 < 1.6 × 108 M⊙ Mpc−3 at z ~ 3 given additional model assumptions. These limits narrow the model space significantly compared to previous CO line-intensity mapping results while maintaining consistency with small-volume interferometric surveys of resolved line candidates. The results also express a weak preference for CO emission models used to guide fiducial forecasts from COMAP Early Science, including our data-driven priors. We also consider directly constraining a model of the halo–CO connection, and show qualitative hints of capturing the total contribution of faint CO emitters through the improved sensitivity of COMAP data. With continued observations and matching improvements in analysis, the COMAP Pathfinder remains on track for a detection of cosmological clustering of CO emission.

• Lunde, Jonas Gahr Sturtzel; Stutzer, Nils-Ole; Breysse, P.C.; Chung, D.T.; Cleary, K.A. & Dunne, D.A. [Vis alle 27 forfattere av denne artikkelen] (2024). COMAP Pathfinder – Season 2 results: I. Improved data selection and processing. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 691. doi: 10.1051/0004-6361/202451121. Fulltekst i vitenarkiv Vis sammendrag

  The CO Mapping Array Project (COMAP) Pathfinder is performing line intensity mapping of CO emission to trace the distribution of unresolved galaxies at redshift z ∼ 3. We present an improved version of the COMAP data processing pipeline and apply it to the first two Seasons of observations. This analysis improves on the COMAP Early Science (ES) results in several key aspects. On the observational side, all second season scans were made in constant-elevation mode, after noting that the previous Lissajous scans were associated with increased systematic errors; those scans accounted for 50% of the total Season 1 data volume. In addition, all new observations were restricted to an elevation range of 35–65 degrees to minimize sidelobe ground pickup. On the data processing side, more effective data cleaning in both the time and map domain allowed us to eliminate all data-driven power spectrum-based cuts. This increases the overall data retention and reduces the risk of signal subtraction bias. However, due to the increased sensitivity, two new pointing-correlated systematic errors have emerged, and we introduced a new map-domain PCA filter to suppress these errors. Subtracting only five out of 256 PCA modes, we find that the standard deviation of the cleaned maps decreases by 67% on large angular scales, and after applying this filter, the maps appear consistent with instrumental noise. Combining all of these improvements, we find that each hour of raw Season 2 observations yields on average 3.2 times more cleaned data compared to the ES analysis. Combining this with the increase in raw observational hours, the effective amount of data available for high-level analysis is a factor of eight higher than in the ES analysis. The resulting maps have reached an uncertainty of 25–50 μK per voxel, providing by far the strongest constraints on cosmological CO line emission published to date.

• Paoletti, D.; Rubino-Martin, J.A.; Shiraishi, M.; Molinari, D.; Chluba, J. & Finelli, F. [Vis alle 100 forfattere av denne artikkelen] (2024). LiteBIRD science goals and forecasts: primordial magnetic fields. Journal of Cosmology and Astroparticle Physics (JCAP). 2024(7). doi: 10.1088/1475-7516/2024/07/086. Fulltekst i vitenarkiv Vis sammendrag

  We present detailed forecasts for the constraints on the characteristics of primordial magnetic fields (PMFs) generated prior to recombination that will be obtained with the LiteBIRD satellite. The constraints are driven by some of the main physical effects of PMFs on the CMB anisotropies: the gravitational effects of magnetically-induced perturbations; the effects on the thermal and ionization history of the Universe; the Faraday rotation imprint on the CMB polarization spectra; and the non-Gaussianities induced in polarization anisotropies. LiteBIRD represents a sensitive probe for PMFs. We explore different levels of complexity, for LiteBIRD data and PMF configurations, accounting for possible degeneracies with primordial gravitational waves from inflation. By exploiting all the physical effects, LiteBIRD will be able to improve the current limit on PMFs at intermediate and large scales coming from Planck. In particular, thanks to its accurate B-mode polarization measurement, LiteBIRD will improve the constraints on infrared configurations for the gravitational effect, giving BnB=-2.91 Mpc< 0.8 nG at 95% C.L., potentially opening the possibility to detect nanogauss fields with high significance. We also observe a significant improvement in the limits when marginalized over the spectral index, BnBmarg1 Mpc< 2.2 nG at 95 % C.L. From the thermal history effect, which relies mainly on E-mode polarization data, we obtain a significant improvement for all PMF configurations, with the marginalized case, √⟨B2⟩marg<0.50 nG at 95 % C.L. Faraday rotation constraints will take advantage of the wide frequency coverage of LiteBIRD and the high sensitivity in B modes, improving the limits by orders of magnitude with respect to current results, BnB=-2.91 Mpc < 3.2 nG at 95 % C.L. Finally, non-Gaussianities of the B-mode polarization can probe PMFs at the level of 1 nG, again significantly improving the current bounds from Planck. Altogether our forecasts represent a broad collection of complementary probes based on widely tested methodologies, providing conservative limits on PMF characteristics that will be achieved with the LiteBIRD satellite.

• Takase, Y.; Vacher, L.; Ishino, H.; Patanchon, G.; Montier, L. & Stever, S.L. [Vis alle 108 forfattere av denne artikkelen] (2024). Multi-dimensional optimisation of the scanning strategy for the LiteBIRD space mission. Journal of Cosmology and Astroparticle Physics (JCAP). 2024(12). doi: 10.1088/1475-7516/2024/12/036. Fulltekst i vitenarkiv Vis sammendrag

  Large angular scale surveys in the absence of atmosphere are essential for measuring the primordial B-mode power spectrum of the Cosmic Microwave Background (CMB). Since this proposed measurement is about three to four orders of magnitude fainter than the temperature anisotropies of the CMB, in-flight calibration of the instruments and active suppression of systematic effects are crucial. We investigate the effect of changing the parameters of the scanning strategy on the in-flight calibration effectiveness, the suppression of the systematic effects themselves, and the ability to distinguish systematic effects by null-tests. Next-generation missions such as LiteBIRD, modulated by a Half-Wave Plate (HWP), will be able to observe polarisation using a single detector, eliminating the need to combine several detectors to measure polarisation, as done in many previous experiments and hence avoiding the consequent systematic effects. While the HWP is expected to suppress many systematic effects, some of them will remain. We use an analytical approach to comprehensively address the mitigation of these systematic effects and identify the characteristics of scanning strategies that are the most effective for implementing a variety of calibration strategies in the multi-dimensional space of common spacecraft scan parameters. We verify that LiteBIRD's standard configuration yields good performance on the metrics we studied. We also present Falcons.jl, a fast spacecraft scanning simulator that we developed to investigate this scanning parameter space.

• Campeti, P.; Komatsu, E.; Baccigalupi, C.; Ballardini, M.; Bartolo, N. & Carones, A. [Vis alle 110 forfattere av denne artikkelen] (2024). LiteBIRD science goals and forecasts. A case study of the origin of primordial gravitational waves using large-scale CMB polarization. Journal of Cosmology and Astroparticle Physics (JCAP). 2024(6). doi: 10.1088/1475-7516/2024/06/008. Fulltekst i vitenarkiv Vis sammendrag

  We study the possibility of using the LiteBIRD satellite B-mode survey to constrain models of inflation producing specific features in CMB angular power spectra. We explore a particular model example, i.e. spectator axion-SU(2) gauge field inflation. This model can source parity-violating gravitational waves from the amplification of gauge field fluctuations driven by a pseudoscalar "axionlike" field, rolling for a few e-folds during inflation. The sourced gravitational waves can exceed the vacuum contribution at reionization bump scales by about an order of magnitude and can be comparable to the vacuum contribution at recombination bump scales. We argue that a satellite mission with full sky coverage and access to the reionization bump scales is necessary to understand the origin of the primordial gravitational wave signal and distinguish among two production mechanisms: quantum vacuum fluctuations of spacetime and matter sources during inflation. We present the expected constraints on model parameters from LiteBIRD satellite simulations, which complement and expand previous studies in the literature. We find that LiteBIRD will be able to exclude with high significance standard single-field slow-roll models, such as the Starobinsky model, if the true model is the axion-SU(2) model with a feature at CMB scales. We further investigate the possibility of using the parity-violating signature of the model, such as the TB and EB angular power spectra, to disentangle it from the standard single-field slow-roll scenario. We find that most of the discriminating power of LiteBIRD will reside in BB angular power spectra rather than in TB and EB correlations.

• Leloup, C.; Patanchon, G.; Errard, J.; Franceschet, C.; Gudmundsson, J.E. & Henrot-Versillé, S. [Vis alle 112 forfattere av denne artikkelen] (2024). Impact of beam far side-lobe knowledge in the presence of foregrounds for LiteBIRD. Journal of Cosmology and Astroparticle Physics (JCAP). 2024(6). doi: 10.1088/1475-7516/2024/06/01. Fulltekst i vitenarkiv Vis sammendrag

  We present a study of the impact of a beam far side-lobe lack of knowledge on the measurement of the Cosmic Microwave Background B-mode signal at large scale. Beam far side-lobes induce a mismatch in the transfer function of Galactic foregrounds between the dipole and higher multipoles which degrads the performances of component separation methods. This leads to foreground residuals in the CMB map. It is expected to be one of the main source of systematic effects in future CMB polarization observations. Thus, it becomes crucial for all-sky survey missions to take into account the interplays between beam systematic effects and all the data analysis steps. LiteBIRD is the ISAS/JAXA second strategic large-class satellite mission and is dedicated to target the measurement of CMB primordial B modes by reaching a sensitivity on the tensor-to-scalar ratio r of σ(r) ≤ 10-3 assuming r = 0. The primary goal of this paper is to provide the methodology and develop the framework to carry out the end-to-end study of beam far side-lobe effects for a space-borne CMB experiment. We introduce uncertainties in the beam model, and propagate the beam effects through all the steps of the analysis pipeline, most importantly including component separation, up to the cosmological results in the form of a bias δr. As a demonstration of our framework, we derive requirements on the calibration and modeling for the LiteBIRD's beams under given assumptions on design, simulation, component separation method and allocated error budget. In particular, we assume a parametric method of component separation with no mitigation of the far side-lobes effect at any stage of the analysis pipeline. We show that δr is mostly due to the integrated fractional power difference between the estimated beams and the true beams in the far side-lobes region, with little dependence on the actual shape of the beams, for low enough δr. Under our set of assumptions, in particular considering the specific foreground cleaning method we used, we find that the integrated fractional power in the far side-lobes should be known at the level of ∼ 10-4, to achieve the required limit on the bias δr < 1.9 × 10-5. The framework and tools developed for this study can be easily adapted to provide requirements under different design, data analysis frameworks and for other future space-borne experiments, such as PICO or CMB-Bharat. We further discuss the limitations of this framework and potential extensions to circumvent them.

• Dunne, Delaney A.; Cleary, Kieran A.; Breysse, Patrick C.; Chung, Dongwoo T.; Ihle, Håvard Tveit & Bond, J. Richard [Vis alle 25 forfattere av denne artikkelen] (2024). COMAP Early Science. VIII. A Joint Stacking Analysis with eBOSS Quasars. The Astrophysical Journal (ApJ). ISSN 0004-637X. 965(1). doi: 10.3847/1538-4357/ad2dfc. Fulltekst i vitenarkiv
• Fuskeland, Unni; Kaplan, A.; Wehus, Ingunn Kathrine; Eriksen, Hans Kristian Kamfjord; Christensen, P.R. & Hausegger, S. von [Vis alle 12 forfattere av denne artikkelen] (2024). B-mode polarization forecasts for GreenPol. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 684. doi: 10.1051/0004-6361/202347393. Fulltekst i vitenarkiv Vis sammendrag

  We present tensor-to-scalar ratio forecasts for GreenPol, a hypothetical ground-based B-mode experiment aiming to survey the cleanest regions of the Northern Galactic Hemisphere at five frequencies between 10 and 44 GHz. Its primary science goal would be to measure large-scale cosmic microwave background (CMB) polarization fluctuations at multipoles ℓ ≲ 500, and thereby constrain the primordial tensor-to-scalar ratio r. The observations for the suggested experiment would take place at the Summit Station (72 ° 34N, 38 ° 27W) on Greenland, at an altitude of 3216 m above sea level. For this paper we simulated various experimental setups, and derived limits on the tensor-to-scalar ratio after CMB component separation using a Bayesian component separation implementation called Commander. When combining the proposed experiment with Planck HFI observations for constraining polarized thermal dust emission, we found a projected limit of r < 0.02 at 95% confidence for the baseline configuration. This limit is very robust with respect to a range of important experimental parameters, including sky coverage, detector weighting, foreground priors, among others. Overall, GreenPol would have the possibility to provide deep CMB polarization measurements of the Northern Galactic Hemisphere at low frequencies.

• Shaw, Elle C.; Ade, Peter A. R.; Akers, Scott; Amiri, Mandana; Austermann, Jason & Beall, James [Vis alle 86 forfattere av denne artikkelen] (2024). In-flight performance of Spider's 280-GHz receivers. Journal of Astronomical Telescopes, Instruments, and Systems (JATIS). ISSN 2329-4124. 10(4). doi: 10.1117/1.JATIS.10.4.044012. Fulltekst i vitenarkiv Vis sammendrag

  Spider is a balloon-borne instrument designed to map the cosmic microwave background at degree-angular scales in the presence of Galactic foregrounds. Spider has mapped a large sky area in the Southern Hemisphere using more than 2000 transition-edge sensors (TESs) during two NASA Long Duration Balloon flights above the Antarctic continent. During its first flight in January 2015, Spider was observed in the 95- and 150-GHz frequency bands, setting constraints on the B-mode signature of primordial gravitational waves. Its second flight in the 2022–2023 season added new receivers at 280 GHz, each using an array of TESs coupled to the sky through feedhorns formed from stacks of silicon wafers. These receivers are optimized to produce deep maps of polarized Galactic dust emission over a large sky area, providing a unique data set with lasting value to the field. We describe the instrument’s performance during Spider’s second flight, focusing on the performance of the 280-GHz receivers. We include details on the flight, in-band optical loading at float, and an early analysis of detector noise.

• Shaw, E.C.; Ade, P.A.R.; Akers, S.; Amiri, M.; Austermann, J. & Beall, J. [Vis alle 87 forfattere av denne artikkelen] (2024). In-flight performance of SPIDER's 280 GHz receivers. Proceedings of SPIE, the International Society for Optical Engineering. ISSN 0277-786X. 13102. doi: 10.1117/12.3016837. Fulltekst i vitenarkiv Vis sammendrag

  SPIDER is a balloon-borne instrument designed to map the cosmic microwave background at degree-angular scales in the presence of Galactic foregrounds. Spider has mapped a large sky area in the Southern Hemisphere using more than 2000 transition-edge sensors (TESs) during two NASA Long Duration Balloon flights above the Antarctic continent. During its first flight in January 2015, Spider observed in the 95 GHz and 150 GHz frequency bands, setting constraints on the B-mode signature of primordial gravitational waves. Its second flight in the 2022-23 season added new receivers at 280 GHz, each using an array of TESs coupled to the sky through feedhorns formed from stacks of silicon wafers. These receivers are optimized to produce deep maps of polarized Galactic dust emission over a large sky area, providing a unique data set with lasting value to the field. In this work, we describe the instrument’s performance during SPIDER’s second flight.

• Lonappan, A.I.; Namikawa, T.; Piccirilli, G.; Diego-Palazuelos, P.; Ruiz-Granda, M. & Migliaccio, M. [Vis alle 122 forfattere av denne artikkelen] (2024). LiteBIRD science goals and forecasts: a full-sky measurement of gravitational lensing of the CMB. Journal of Cosmology and Astroparticle Physics (JCAP). 2024(6). doi: 10.1088/1475-7516/2024/06/009. Fulltekst i vitenarkiv Vis sammendrag

  We explore the capability of measuring lensing signals in LiteBIRD full-sky polarization maps. With a 30 arcmin beam width and an impressively low polarization noise of 2.16 μK-arcmin,LiteBIRD will be able to measure the full-sky polarization of the cosmic microwave background (CMB) very precisely. This unique sensitivity also enables the reconstruction of a nearly full-sky lensing map using only polarization data, even considering its limited capability to capture small-scale CMB anisotropies. In this paper, we investigate the ability to construct a full-sky lensing measurement in the presence of Galactic foregrounds, finding that several possible biases from Galactic foregrounds should be negligible after component separation by harmonic-space internal linear combination. We find that the signal-to-noise ratio of the lensing is approximately 40 using only polarization data measured over 80% of the sky. This achievement is comparable to Planck's recent lensing measurement with both temperature and polarization and represents a four-fold improvement over Planck's polarization-only lensing measurement. The LiteBIRD lensing map will complement the Planck lensing map and provide several opportunities for cross-correlation science, especially in the northern hemisphere.

• Watts, Duncan; Fuskeland, Unni; Aurvik, Ragnhild; Basyrov, Artem; Bianchi, L.A. & Brilenkov, Maksym [Vis alle 21 forfattere av denne artikkelen] (2024). COSMOGLOBE DR1 results: III. First full-sky model of polarized synchrotron emission from all WMAP and Planck LFI data. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 686. doi: 10.1051/0004-6361/202348330. Fulltekst i vitenarkiv Vis sammendrag

  We present the first model of full-sky polarized synchrotron emission that is derived from all WMAP and Planck LFI frequency maps. The basis of this analysis is the set of end-to-end reprocessed COSMOGLOBE Data Release 1 (DR1) sky maps presented in a companion paper, which have significantly lower instrumental systematics than the legacy products from each experiment. We find that the resulting polarized synchrotron amplitude map has an average noise rms per 2° full width at half maximum (FWHM) beam of 3.2 μK at 30 GHz. This is 30% lower than the recently released BEYONDPLANCK model that included only LFI+WMAP Ka–V data, and 29% lower than the WMAP K-band map alone. The mean B-to-E power spectrum ratio is 0.39 ± 0.02, with amplitudes consistent with those measured previously by Planck and QUIJOTE. Assuming a power law model for the synchrotron spectral energy distribution and using the T–T plot method, we find a full-sky inverse noise-variance-weighted mean of the synchrotron polarized spectral index of βs = −3.07 ± 0.07 from the COSMOGLOBE DR1 K band and 30 GHz, in good agreement with previous estimates. In summary, the novel COSMOGLOBE DR1 synchrotron model is both more sensitive and systematically cleaner than similar previous models, and it has a more complete error description that is defined by a set of Monte Carlo posterior samples. We believe that these products are preferable over previous Planck and WMAP products for all synchrotron-related scientific applications, including simulations, forecasting, and component separation.

• Namikawa, T.; Lonappan, A.; Baccigalupi, C.; Bartolo, N.; Beck, D. & Benabed, K. [Vis alle 122 forfattere av denne artikkelen] (2024). LiteBIRD science goals and forecasts: improving sensitivity to inflationary gravitational waves with multitracer delensing. Journal of Cosmology and Astroparticle Physics (JCAP). 2024(6). doi: 10.1088/1475-7516/2024/06/010. Fulltekst i vitenarkiv Vis sammendrag

  We estimate the efficiency of mitigating the lensing B-mode polarization, the so-called delensing, for the LiteBIRD experiment with multiple external data sets of lensing-mass tracers. The current best bound on the tensor-to-scalar ratio, r, is limited by lensing rather than Galactic foregrounds. Delensing will be a critical step to improve sensitivity to r as measurements of r become more and more limited by lensing. In this paper, we extend the analysis of the recent LiteBIRD forecast paper to include multiple mass tracers, i.e., the CMB lensing maps from LiteBIRD and CMB-S4-like experiment, cosmic infrared background, and galaxy number density from Euclid- and LSST-like survey. We find that multi-tracer delensing will further improve the constraint on r by about 20%. In LiteBIRD, the residual Galactic foregrounds also significantly contribute to uncertainties of the B-modes, and delensing becomes more important if the residual foregrounds are further reduced by an improved component separation method.

• Basyrov, Artem; Stutzer, Nils-Ole; Lunde, Jonas Gahr Sturtzel; Eriksen, Hans Kristian Kamfjord; Gjerløw, Eirik & Watts, Duncan [Vis alle 7 forfattere av denne artikkelen] (2024). Optimal bolometer transfer function deconvolution for CMB experiments through maximum likelihood mapmaking. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 688. doi: 10.1051/0004-6361/202450712. Fulltekst i vitenarkiv Vis sammendrag

  We revisit the impact of finite time responses of bolometric detectors used for deep observations of the cosmic microwave background (CMB). Until now, bolometer transfer functions have been accounted for through a two-step procedure by first deconvolving an estimate of their Fourier-space representation from the raw time-ordered data (TOD), and then averaging the deconvolved TOD into pixelized maps. However, for many experiments, including the Planck High Frequency Instrument (HFI), it is necessary to apply an additional low-pass filter to avoid an excessive noise boost, which leads to an asymmetric effective beam. In this paper we demonstrate that this effect can be avoided if the transfer function deconvolution and pixelization operations are performed simultaneously through integrated maximum likelihood mapmaking. The resulting algorithm is structurally identical to the artDeco algorithm for beam deconvolution. We illustrate the relevance of this method with simulated Planck HFI 143 GHz data, and find that the resulting effective beam is both more symmetric than with the two-step procedure, resulting in a sky-averaged ellipticity that is 64% lower, and an effective beam full-width-at-half-maximum (FWHM) that is 2.3% smaller. Similar improvements are expected for any other bolometer-based CMB experiments with long time constants.

• Eskilt, Johannes Røsok; Watts, Duncan; Aurvik, Ragnhild; Basyrov, Artem; Bersanelli, Marco & Brilenkov, Maksym [Vis alle 31 forfattere av denne artikkelen] (2023). Cosmoglobe DR1 results II. Constraints on isotropic cosmic birefringence from reprocessed WMAP and Planck LFI data. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 679. doi: 10.1051/0004-6361/202346829. Fulltekst i vitenarkiv Vis sammendrag

  Cosmic birefringence is a parity-violating effect that might have rotated the plane of the linearly polarized light of the cosmic microwave background (CMB) by an angle β since its emission. This angle has recently been measured to be nonzero at a statistical significance of 3.6 σ in the official Planck PR4 and 9-year WMAP data. In this work, we constrain β using the reprocessed B EYOND P LANCK LFI and C OSMOGLOBE DR1 WMAP polarization maps. These novel maps have both lower systematic residuals and a more complete error description than the corresponding official products. Foreground EB correlations could bias measurements of β , and while thermal dust EB emission has been argued to be statistically nonzero, no evidence for synchrotron EB power has been reported. Unlike the dust-dominated Planck HFI maps, the majority of the LFI and WMAP polarization maps are instead dominated by synchrotron emission. Simultaneously constraining β and the polarization miscalibration angle, α , of each channel, we find a best-fit value of β  = 0.35° ±0.70° with LFI and WMAP data only. When including the Planck HFI PR4 maps, but fitting β separately for dust-dominated, β &gt; 70 GHz , and synchrotron-dominated channels, β ≤70 GHz , we find β ≤70 GHz  = 0.53° ±0.28°. This differs from zero with a statistical significance of 1.9 σ , and the main contribution to this value comes from the LFI 70 GHz channel. While the statistical significances of these results are low on their own, the measurement derived from the LFI and WMAP synchrotron-dominated maps agrees with the previously reported HFI-dominated constraints, despite the very different astrophysical and instrumental systematics involved in all these experiments.

• Brilenkov, Maksym; Fornazier, K.S.F.; Hergt, L.T.; Hoerning, G.A.; Marins, A. & Murokoshi, T. [Vis alle 51 forfattere av denne artikkelen] (2023). BeyondPlanck: IV. Simulations and validation. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 675. doi: 10.1051/0004-6361/202244958. Fulltekst i vitenarkiv Vis sammendrag

  End-to-end simulations play a key role in the analysis of any high-sensitivity cosmic microwave background (CMB) experiment, providing high-fidelity systematic error propagation capabilities that are unmatched by any other means. In this paper, we address an important issue regarding such simulations, namely, how to define the inputs in terms of sky model and instrument parameters. These may either be taken as a constrained realization derived from the data or as a random realization independent from the data. We refer to these as posterior and prior simulations, respectively. We show that the two options lead to significantly different correlation structures, as prior simulations (contrary to posterior simulations) effectively include cosmic variance, but they exclude realization-specific correlations from non-linear degeneracies. Consequently, they quantify fundamentally different types of uncertainties. We argue that as a result, they also have different and complementary scientific uses, even if this dichotomy is not absolute. In particular, posterior simulations are in general more convenient for parameter estimation studies, while prior simulations are generally more convenient for model testing. Before B EYOND P LANCK , most pipelines used a mix of constrained and random inputs and applied the same hybrid simulations for all applications, even though the statistical justification for this is not always evident. B EYOND P LANCK represents the first end-to-end CMB simulation framework that is able to generate both types of simulations and these new capabilities have brought this topic to the forefront. The B EYOND P LANCK posterior simulations and their uses are described extensively in a suite of companion papers. In this work, we consider one important applications of the corresponding prior simulations, namely, code validation. Specifically, we generated a set of one-year LFI 30 GHz prior simulations with known inputs and we used these to validate the core low-level B EYOND P LANCK algorithms dealing with gain estimation, correlated noise estimation, and mapmaking.

• Aurvik, Ragnhild; Remazeilles, Mathieu; Belkner, Sebastian; Carron, Julien; Delabrouille, Jacques & Eriksen, Hans Kristian Kamfjord [Vis alle 17 forfattere av denne artikkelen] (2023). Foreground separation and constraints on primordial gravitational waves with the PICO space mission. Journal of Cosmology and Astroparticle Physics (JCAP). 2023(6). doi: 10.1088/1475-7516/2023/06/034. Fulltekst i vitenarkiv Vis sammendrag

  PICO is a concept for a NASA probe-scale mission aiming to detect or constrain the tensor to scalar ratio r, a parameter that quantifies the amplitude of inflationary gravity waves. We carry out map-based component separation on simulations with five foreground models and input r values rin = 0 and rin = 0.003. We forecast r determinations using a Gaussian likelihood assuming either no delensing or a residual lensing factor Alens = 27%. By implementing the first full-sky, post component-separation, map-domain delensing, we show that PICO should be able to achieve Alens = 22% – 24%. For four of the five foreground models we find that PICO would be able to set the constraints r < 1.3 × 10-4 to r < 2.7 × 10-4 (95%) if rin = 0, the strongest constraints of any foreseeable instrument. For these models, r = 0.003 is recovered with confidence levels between 18σ and 27σ. We find weaker, and in some cases significantly biased, upper limits when removing few low or high frequency bands. The fifth model gives a 3σ detection when rin = 0 and a 3σ bias with rin = 0.003. However, by correlating r determinations from many small 2.5% sky areas with the mission's 555 GHz data we identify and mitigate the bias. This analysis underscores the importance of large sky coverage. We show that when only low multipoles ℓ ≤ 12 are used, the non-Gaussian shape of the true likelihood gives uncertainties that are on average 30% larger than a Gaussian approximation.

• Fuskeland, Unni; Aumont, J.; Aurvik, Ragnhild; Baccigalupi, C.; Banday, A.J. & Eriksen, Hans Kristian Kamfjord [Vis alle 117 forfattere av denne artikkelen] (2023). Tensor-to-scalar ratio forecasts for extended LiteBIRD frequency configurations. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 676. doi: 10.1051/0004-6361/202346155. Fulltekst i vitenarkiv Vis sammendrag

  LiteBIRD is a planned JAXA-led cosmic microwave background (CMB) B -mode satellite experiment aiming for launch in the late 2020s, with a primary goal of detecting the imprint of primordial inflationary gravitational waves. Its current baseline focal-plane configuration includes 15 frequency bands between 40 and 402 GHz, fulfilling the mission requirements to detect the amplitude of gravitational waves with the total uncertainty on the tensor-to-scalar ratio, δr , down to δr  &lt; 0.001. A key aspect of this performance is accurate astrophysical component separation, and the ability to remove polarized thermal dust emission is particularly important. In this paper we note that the CMB frequency spectrum falls off nearly exponentially above 300 GHz relative to the thermal dust spectral energy distribution, and a relatively minor high frequency extension can therefore result in even lower uncertainties and better model reconstructions. Specifically, we compared the baseline design with five extended configurations, while varying the underlying dust modeling, in each of which the High-Frequency Telescope (HFT) frequency range was shifted logarithmically toward higher frequencies, with an upper cutoff ranging between 400 and 600 GHz. In each case, we measured the tensor-to-scalar ratio r uncertainty and bias using both parametric and minimum-variance component-separation algorithms. When the thermal dust sky model includes a spatially varying spectral index and temperature, we find that the statistical uncertainty on r after foreground cleaning may be reduced by as much as 30–50% by extending the upper limit of the frequency range from 400 to 600 GHz, with most of the improvement already gained at 500 GHz. We also note that a broader frequency range leads to higher residuals when fitting an incorrect dust model, but also it is easier to discriminate between models through higher χ 2 sensitivity. Even in the case in which the fitting procedure does not correspond to the underlying dust model in the sky, and when the highest frequency data cannot be modeled with sufficient fidelity and must be excluded from the analysis, the uncertainty on r increases by only about 5% for a 500 GHz configuration compared to the baseline.

• Eskilt, Johannes Røsok; Lee, Katherine; Watts, Duncan; Anshul, V.; Aurvik, Ragnhild & Basyrov, Artem [Vis alle 23 forfattere av denne artikkelen] (2023). COSMOGLOBE: Towards end-to-end CMB cosmological parameter estimation without likelihood approximations. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 678. doi: 10.1051/0004-6361/202347358. Fulltekst i vitenarkiv Vis sammendrag

  We implement support for a cosmological parameter estimation algorithm in Commander and quantify its computational efficiency and cost. For a semi-realistic simulation similar to Planck LFI 70 GHz, we find that the computational cost of producing one single sample is about 20 CPU-hours and that the typical Markov chain correlation length is ∼100 samples. The net effective cost per independent sample is ∼2000 CPU-hours, in comparison with all low-level processing costs of 812 CPU-hours for Planck LFI and WMAP in C OSMOGLOBE Data Release 1. Thus, although technically possible to run already in its current state, future work should aim to reduce the effective cost per independent sample by one order of magnitude to avoid excessive runtimes, for instance through multi-grid preconditioners and/or derivative-based Markov chain sampling schemes. This work demonstrates the computational feasibility of true Bayesian cosmological parameter estimation with end-to-end error propagation for high-precision CMB experiments without likelihood approximations, but it also highlights the need for additional optimizations before it is ready for full production-level analysis.

• Svalheim, Trygve Leithe; Andersen, Kristian Joten; Aurvik, Ragnhild; Banerji, Ranajoy; Bersanelli, M. & Bertocco, S. [Vis alle 38 forfattere av denne artikkelen] (2023). BeyondPlanck: XIV. Polarized foreground emission between 30 and 70 GHz. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 675. doi: 10.1051/0004-6361/202243160. Fulltekst i vitenarkiv Vis sammendrag

  Using the Planck Low Frequency Instrument (LFI) and WMAP data within the global Bayesian B EYOND P LANCK framework, we constrained the polarized foreground emission between 30 and 70 GHz. We combined, for the first time, full-resolution Planck LFI time-ordered data with low-resolution WMAP sky maps at 33, 40, and 61 GHz. The spectral parameters were fit with a likelihood defined at the native resolution of each frequency channel. This analysis represents the first implementation of true multi-resolution component separation applied to CMB observations for both amplitude and spectral energy distribution (SED) parameters. For the synchrotron emission, we approximated the SED as a power-law in frequency and we find that the low signal-to-noise ratio of the current data strongly limits the number of free parameters that can be robustly constrained. We partitioned the sky into four large disjoint regions (High Latitude; Galactic Spur; Galactic Plane; and Galactic Center), each associated with its own power-law index. We find that the High Latitude region is prior-dominated, while the Galactic Center region is contaminated by residual instrumental systematics. The two remaining regions appear to be signal-dominated, and for these we derive spectral indices of β s Spur  = −3.17 ± 0.06 and β s Plane  = −3.03 ± 0.07, which is in good agreement with previous results. For the thermal dust emission, we assumed a modified blackbody model and we fit a single power-law index across the full sky. We find β d  = 1.64 ± 0.03, which is slightly steeper than the value reported in Planck HFI data, but still statistically consistent at the 2 σ confidence level.

• Watts, Duncan; Basyrov, Artem; Eskilt, Johannes Røsok; Galloway, Mathew; Gjerløw, Eirik & Hergt, L.T. [Vis alle 33 forfattere av denne artikkelen] (2023). COSMOGLOBE DR1 results: I. Improved Wilkinson Microwave Anisotropy Probe maps through Bayesian end-to-end analysis. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 679. doi: 10.1051/0004-6361/202346414. Fulltekst i vitenarkiv Vis sammendrag

  We present C OSMOGLOBE Data Release 1, which implements the first joint analysis of WMAP and Planck LFI time-ordered data, processed within a single Bayesian end-to-end framework. This framework directly builds on a similar analysis of the LFI measurements by the B EYOND P LANCK collaboration, and approaches the cosmic microwave background (CMB) analysis challenge through Gibbs sampling of a global posterior distribution, simultaneously accounting for calibration, mapmaking, and component separation. The computational cost of producing one complete WMAP+LFI Gibbs sample is 812 CPU-h, of which 603 CPU-h are spent on WMAP low-level processing; this demonstrates that end-to-end Bayesian analysis of the WMAP data is computationally feasible. We find that our WMAP posterior mean temperature sky maps and CMB temperature power spectrum are largely consistent with the official WMAP9 results. Perhaps the most notable difference is that our CMB dipole amplitude is 3366.2 ± 1.4 μK, which is 11 μK higher than the WMAP9 estimate and 2.5 σ higher than B EYOND P LANCK ; however, it is in perfect agreement with the HFI-dominated Planck PR4 result. In contrast, our WMAP polarization maps differ more notably from the WMAP9 results, and in general exhibit significantly lower large-scale residuals. We attribute this to a better constrained gain and transmission imbalance model. It is particularly noteworthy that the W -band polarization sky map, which was excluded from the official WMAP cosmological analysis, for the first time appears visually consistent with the V -band sky map. Similarly, the long standing discrepancy between the WMAP K -band and LFI 30 GHz maps is finally resolved, and the difference between the two maps appears consistent with instrumental noise at high Galactic latitudes. Relatedly, these updated maps allowed us for the first time to combine WMAP and LFI polarization data into a single coherent model of large-scale polarized synchrotron emission. Still, we identified a few issues that require additional work, including (1) low-level noise modeling; (2) large-scale temperature residuals at the 1–2 μK level; and (3) a strong degeneracy between the absolute K -band calibration and the dipole of the anomalous microwave emission component. We conclude that leveraging the complementary strengths of WMAP and LFI has allowed the mitigation of both experiments’ weaknesses, and resulted in new state-of-the-art WMAP sky maps. All maps and the associated code are made publicly available through the C OSMOGLOBE web page.

• Herman, Daniel Christopher; Hensley, B.; Andersen, Kristian Joten; Aurvik, Ragnhild; Banerji, Ranajoy & Bersanelli, M. [Vis alle 36 forfattere av denne artikkelen] (2023). BeyondPlanck: XV. Limits on large-scale polarized anomalous microwave emission from Planck LFI and WMAP. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 675. doi: 10.1051/0004-6361/202243081. Fulltekst i vitenarkiv Vis sammendrag

  We constrained the level of polarized anomalous microwave emission (AME) on large angular scales using Planck Low-Frequency Instrument (LFI) and WMAP polarization data within a Bayesian cosmic microwave background (CMB) analysis framework. We modeled synchrotron emission with a power-law spectral energy distribution, as well as the sum of AME and thermal dust emission through linear regression with the Planck High-Frequency Instrument (HFI) 353 GHz data. This template-based dust emission model allowed us to constrain the level of polarized AME while making minimal assumptions on its frequency dependence. We neglected CMB fluctuations, but show through simulations that these fluctuations have a minor impact on the results. We find that the resulting AME polarization fraction confidence limit is sensitive to the polarized synchrotron spectral index prior. In addition, for prior means β s  &lt; −3.1 we find an upper limit of p AME max  ≲ 0.6% (95% confidence). In contrast, for means β s  = −3.0, we find a nominal detection of p AME  = 2.5 ± 1.0% (95% confidence). These data are thus not strong enough to simultaneously and robustly constrain both polarized synchrotron emission and AME, and our main result is therefore a constraint on the AME polarization fraction explicitly as a function of β s . Combining the current Planck and WMAP observations with measurements from high-sensitivity low-frequency experiments such as C-BASS and QUIJOTE will be critical to improve these limits further.

• Colombo, L.P.L.; Eskilt, Johannes Røsok; Paradiso, S.; Thommesen, Harald; Andersen, Kristian Joten & Aurvik, Ragnhild [Vis alle 40 forfattere av denne artikkelen] (2023). BeyondPlanck: XI. Bayesian CMB analysis with sample-based end-to-end error propagation. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 675. doi: 10.1051/0004-6361/202244619. Fulltekst i vitenarkiv
• Gjerløw, Eirik; Ihle, Håvard Tveit; Galeotta, S.; Andersen, Kristian Joten; Aurvik, Ragnhild & Banerji, Ranajoy [Vis alle 38 forfattere av denne artikkelen] (2023). BeyondPlanck: VII. Bayesian estimation of gain and absolute calibration for cosmic microwave background experiments. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 675. doi: 10.1051/0004-6361/202244061. Fulltekst i vitenarkiv Vis sammendrag

  We present a Bayesian calibration algorithm for cosmic microwave background (CMB) observations as implemented within the global end-to-end B EYOND P LANCK framework and applied to the Planck Low Frequency Instrument (LFI) data. Following the most recent Planck analysis, we decomposed the full time-dependent gain into a sum of three nearly orthogonal components: one absolute calibration term, common to all detectors, one time-independent term that can vary between detectors, and one time-dependent component that was allowed to vary between one-hour pointing periods. Each term was then sampled conditionally on all other parameters in the global signal model through Gibbs sampling. The absolute calibration is sampled using only the orbital dipole as a reference source, while the two relative gain components were sampled using the full sky signal, including the orbital and Solar CMB dipoles, CMB fluctuations, and foreground contributions. We discuss various aspects of the data that influence gain estimation, including the dipole-polarization quadrupole degeneracy and processing masks. Comparing our solution to previous pipelines, we find good agreement in general, with relative deviations of −0.67% (−0.84%) for 30 GHz, 0.12% (−0.04%) for 44 GHz and −0.03% (−0.64%) for 70 GHz, compared to Planck PR4 and Planck 2018, respectively. We note that the B EYOND P LANCK calibration was performed globally, which results in better inter-frequency consistency than previous estimates. Additionally, WMAP observations were used actively in the B EYOND P LANCK analysis, which both breaks internal degeneracies in the Planck data set and results in an overall better agreement with WMAP. Finally, we used a Wiener filtering approach to smoothing the gain estimates. We show that this method avoids artifacts in the correlated noise maps as a result of oversmoothing the gain solution, which is difficult to avoid with methods like boxcar smoothing, as Wiener filtering by construction maintains a balance between data fidelity and prior knowledge. Although our presentation and algorithm are currently oriented toward LFI processing, the general procedure is fully generalizable to other experiments, as long as the Solar dipole signal is available to be used for calibration.

• Paradiso, S.; Colombo, L.P.L.; Andersen, Kristian Joten; Aurvik, Ragnhild; Banerji, Ranajoy & Basyrov, Artem [Vis alle 41 forfattere av denne artikkelen] (2023). BeyondPlanck: XII. Cosmological parameter constraints with end-to-end error propagation. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 675. doi: 10.1051/0004-6361/202244060. Fulltekst i vitenarkiv Vis sammendrag

  We present cosmological parameter constraints estimated using the Bayesian B EYOND P LANCK analysis framework. This method supports seamless end-to-end error propagation from raw time-ordered data onto final cosmological parameters. As a first demonstration of the method, we analyzed time-ordered Planck LFI observations, combined with selected external data (WMAP 33–61 GHz, Planck HFI DR4 353 and 857 GHz, and Haslam 408 MHz) in the form of pixelized maps that are used to break critical astrophysical degeneracies. Overall, all the results are generally in good agreement with previously reported values from Planck 2018 and WMAP, with the largest relative difference for any parameter amounting about 1 σ when considering only temperature multipoles between 30 ≤  ℓ  ≤ 600. In cases where there are differences, we note that the B EYOND P LANCK results are generally slightly closer to the high- ℓ HFI-dominated Planck 2018 results than previous analyses, suggesting slightly less tension between low and high multipoles. Using low- ℓ polarization information from LFI and WMAP, we find a best-fit value of τ  = 0.066 ± 0.013, which is higher than the low value of τ  = 0.052 ± 0.008 derived from Planck 2018 and slightly lower than the value of 0.069 ± 0.011 derived from the joint analysis of official LFI and WMAP products. Most importantly, however, we find that the uncertainty derived in the B EYOND P LANCK processing is about 30 % greater than when analyzing the official products, after taking into account the different sky coverage. We argue that this uncertainty is due to a marginalization over a more complete model of instrumental and astrophysical parameters, which results in more reliable and more rigorously defined uncertainties. We find that about 2000 Monte Carlo samples are required to achieve a robust convergence for a low-resolution cosmic microwave background (CMB) covariance matrix with 225 independent modes, and producing these samples takes about eight weeks on a modest computing cluster with 256 cores.

• Maharana, S.; Kiehlmann, S.; Blinov, D.; Pelgrims, V.; Pavlidou, V. & Tassis, K. [Vis alle 23 forfattere av denne artikkelen] (2023). Bright-Moon sky as a wide-field linear Polarimetric flat source for calibration. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 679. doi: 10.1051/0004-6361/202346830. Fulltekst i vitenarkiv Vis sammendrag

  Context. Next-generation wide-field optical polarimeters such as Wide-Area Linear Optical Polarimeters (WALOPs) have a field of view (FoV) of tens of arcminutes. Wide-field polarimetric flat sources are essential to the efficient and accurate calibration of these instruments. However, no established wide-field polarimetric standard or flat sources exist at present. Aims. This study tests the feasibility of using the polarized sky patches of the size of around 10 × 10 arcminutes 2 , at a distance of up to 20° from the Moon, on bright-Moon nights as a wide-field linear polarimetric flat source. Methods. We observed 19 patches of the sky adjacent to the bright-Moon with the RoboPol instrument in the SDSS- r broadband filter. These patches were observed on five nights within two days of the full-Moon across two RoboPol observing seasons. Results. We find that for 18 of the 19 patches, the uniformity in the measured normalized Stokes parameters q and u is within 0.2%, with 12 patches exhibiting uniformity within 0.07% or better for both q and u simultaneously, making them reliable and stable wide-field linear polarization flats. Conclusions. We demonstrate that the sky on bright-Moon nights is an excellent wide-field linear polarization flat source. Various combinations of the normalized Stokes parameters q and u can be obtained by choosing suitable locations of the sky patch with respect to the Moon.

• Gerakakis, S.; Brilenkov, Maksym; Ieronymaki, M.; San, Metin; Watts, Duncan & Andersen, Kristian Joten [Vis alle 42 forfattere av denne artikkelen] (2023). From BeyondPlanck to Cosmoglobe: Open Science, Reproducibility, and Data Longevity. The Open Journal of Astrophysics. 6. doi: 10.21105/astro.2205.11262. Fulltekst i vitenarkiv Vis sammendrag

  The BeyondPlanck and Cosmoglobe collaborations have implemented the first integrated Bayesian end-to-end analysis pipeline for CMB experiments. The primary long-term motivation for this work is to develop a common analysis platform that supports efficient global joint analysis of complementary radio, microwave, and sub-millimeter experiments. A strict prerequisite for this to succeed is broad participation from the CMB community, and two foundational aspects of the program are therefore reproducibility and Open Science. In this paper, we discuss our efforts toward this aim. We also discuss measures toward facilitating easy code and data distribution, community-based code documentation, user-friendly compilation procedures, etc. This work represents the first publicly released end-to-end CMB analysis pipeline that includes raw data, source code, parameter files, and documentation. We argue that such a complete pipeline release should be a requirement for all major future and publicly-funded CMB experiments, noting that a full public release significantly increases data longevity by ensuring that the data quality can be improved whenever better processing techniques, complementary datasets, or more computing power become available, and thereby also taxpayers’ value for money; providing only raw data and final products is not sufficient to guarantee full reproducibility in the future.

• Allys, E.; Arnold, K.; Aumont, J.; Aurvik, Ragnhild; Azzoni, S. & Baccigalupi, C. [Vis alle 190 forfattere av denne artikkelen] (2023). Probing cosmic inflation with the LiteBIRD cosmic microwave background polarization survey. Progress of Theoretical and Experimental Physics. 2023(4). doi: 10.1093/ptep/ptac150. Fulltekst i vitenarkiv Vis sammendrag

  LiteBIRD, the Lite (Light) satellite for the study of B-mode polarization and Inflation from cosmic background Radiation Detection, is a space mission for primordial cosmology and fundamental physics. The Japan Aerospace Exploration Agency (JAXA) selected LiteBIRD in May 2019 as a strategic large-class (L-class) mission, with an expected launch in the late 2020s using JAXA’s H3 rocket. LiteBIRD is planned to orbit the Sun–Earth Lagrangian point L2, where it will map the cosmic microwave background polarization over the entire sky for three years, with three telescopes in 15 frequency bands between 34 and 448 GHz, to achieve an unprecedented total sensitivity of 2.2μK-arcmin, with a typical angular resolution of 0.5○ at 100 GHz. The primary scientific objective of LiteBIRD is to search for the signal from cosmic inflation, either making a discovery or ruling out well-motivated inflationary models. The measurements of LiteBIRD will also provide us with insight into the quantum nature of gravity and other new physics beyond the standard models of particle physics and cosmology. We provide an overview of the LiteBIRD project, including scientific objectives, mission and system requirements, operation concept, spacecraft and payload module design, expected scientific outcomes, potential design extensions, and synergies with other projects.

• Watts, Duncan; Galloway, Mathew; Ihle, Håvard Tveit; Andersen, Kristian Joten; Aurvik, Ragnhild & Banerji, Ranajoy [Vis alle 43 forfattere av denne artikkelen] (2023). From BeyondPlanck to Cosmoglobe: Preliminary WMAP Q-band analysis. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 675. doi: 10.1051/0004-6361/202243410. Fulltekst i vitenarkiv Vis sammendrag

  We present the first application of the C OSMOGLOBE analysis framework by analyzing nine-year WMAP time-ordered observations that uses similar machinery to that of B EYOND P LANCK for the Planck Low Frequency Instrument (LFI). We analyzed only the Q -band (41 GHz) data and report on the low-level analysis process based on uncalibrated time-ordered data to calibrated maps. Most of the existing B EYOND P LANCK pipeline may be reused for WMAP analysis with minimal changes to the existing codebase. The main modification is the implementation of the same preconditioned biconjugate gradient mapmaker used by the WMAP team. Producing a single WMAP Q 1-band sample requires 22 CPU-hrs, which is slightly more than the cost of a Planck 44 GHz sample of 17 CPU-hrs; this demonstrates that a full end-to-end Bayesian processing of the WMAP data is computationally feasible. In general, our recovered maps are very similar to the maps released by the WMAP team, although with two notable differences. In terms of temperature, we find a ∼2 μK quadrupole difference that most likely is caused by different gain modeling, while in polarization we find a distinct 2.5 μK signal that has been previously referred to as poorly measured modes by the WMAP team. In the C OSMOGLOBE processing, this pattern arises from temperature-to-polarization leakage from the coupling between the CMB Solar dipole, transmission imbalance, and sidelobes. No traces of this pattern are found in either the frequency map or TOD residual map, suggesting that the current processing has succeeded in modeling these poorly measured modes within the assumed parametric model by using Planck information to break the sky-synchronous degeneracies inherent in the WMAP scanning strategy.

• Basyrov, Artem; Suur-Uski, A.-S.; Colombo, L.P.L.; Eskilt, Johannes Røsok; Paradiso, S. & Andersen, Kristian Joten [Vis alle 40 forfattere av denne artikkelen] (2023). BeyondPlanck: X. Planck Low Frequency Instrument frequency maps with sample-based error propagation. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 675. doi: 10.1051/0004-6361/202244819. Fulltekst i vitenarkiv Vis sammendrag

  We present Planck Low Frequency Instrument (LFI) frequency sky maps derived within the B EYOND P LANCK framework. This framework draws samples from a global posterior distribution that includes instrumental, astrophysical, and cosmological parameters, and the main product is an entire ensemble of frequency sky map samples, each of which corresponds to one possible realization of the various modeled instrumental systematic corrections, including correlated noise, time-variable gain, as well as far sidelobe and bandpass corrections. This ensemble allows for computationally convenient end-to-end propagation of low-level instrumental uncertainties into higher-level science products, including astrophysical component maps, angular power spectra, and cosmological parameters. We show that the two dominant sources of LFI instrumental systematic uncertainties are correlated noise and gain fluctuations, and the products presented here support – for the first time – full Bayesian error propagation for these effects at full angular resolution. We compared our posterior mean maps with traditional frequency maps delivered by the Planck Collaboration, and find generally good agreement. The most important quality improvement is due to significantly lower calibration uncertainties in the new processing, as we find a fractional absolute calibration uncertainty at 70 GHz of Δ g 0 / g 0  = 5 × 10 −5 , which is nominally 40 times smaller than that reported by Planck 2018. However, we also note that the original Planck 2018 estimate has a nontrivial statistical interpretation, and this further illustrates the advantage of the new framework in terms of producing self-consistent and well-defined error estimates of all involved quantities without the need of ad hoc uncertainty contributions. We describe how low-resolution data products, including dense pixel-pixel covariance matrices, may be produced from the posterior samples directly, without the need for computationally expensive analytic calculations or simulations. We conclude that posterior-based frequency map sampling provides unique capabilities in terms of low-level systematics modeling and error propagation, and may play an important role for future Cosmic Microwave Background (CMB) B -mode experiments aiming at nanokelvin precision.

• Galloway, Mathew; Reinecke, M.; Andersen, Kristian Joten; Aurvik, Ragnhild; Banerji, Ranajoy & Bersanelli, M. [Vis alle 41 forfattere av denne artikkelen] (2023). BeyondPlanck: VIII. Efficient sidelobe convolution and corrections through spin harmonics. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 675. doi: 10.1051/0004-6361/202243138. Fulltekst i vitenarkiv Vis sammendrag

  We introduce a new formulation of the Conviqt convolution algorithm in terms of spin harmonics, and apply this to the problem of sidelobe correction for B EYOND P LANCK , the first end-to-end Bayesian Gibbs sampling framework for CMB analysis. We compare our implementation to the previous Planck LevelS implementation, and find good agreement between the two codes in terms of accuracy, but with a speed-up reaching a factor of 3–10, depending on the frequency bandlimits, l max and m max . The new algorithm is significantly simpler to implement and maintain, since all low-level calculations are handled through an external spherical harmonic transform library. We find that our mean sidelobe estimates for Planck LFI are in good agreement with previous efforts. Additionally, we present novel sidelobe rms maps that quantify the uncertainty in the sidelobe corrections due to variations in the sky model.

• Galloway, Mathew; Andersen, Kristian Joten; Aurvik, Ragnhild; Banerji, Ranajoy; Bersanelli, M. & Bertocco, S. [Vis alle 41 forfattere av denne artikkelen] (2023). BeyondPlanck: III. Commander3. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 675. doi: 10.1051/0004-6361/202243137. Fulltekst i vitenarkiv Vis sammendrag

  We describe the computational infrastructure for end-to-end Bayesian cosmic microwave background (CMB) analysis implemented by the BeyondPlanck Collaboration. The code is called Commander3 . It provides a statistically consistent framework for global analysis of CMB and microwave observations and may be useful for a wide range of legacy, current, and future experiments. The paper has three main goals. Firstly, we provide a high-level overview of the existing code base, aiming to guide readers who wish to extend and adapt the code according to their own needs or re-implement it from scratch in a different programming language. Secondly, we discuss some critical computational challenges that arise within any global CMB analysis framework, for instance in-memory compression of time-ordered data, fast Fourier transform optimization, and parallelization and load-balancing. Thirdly, we quantify the CPU and RAM requirements for the current B EYOND P LANCK analysis, finding that a total of 1.5 TB of RAM is required for efficient analysis and that the total cost of a full Gibbs sample for LFI is 170 CPU-hrs, including both low-level processing and high-level component separation, which is well within the capabilities of current low-cost computing facilities. The existing code base is made publicly available under a GNU General Public Library (GPL) license.

• Keihänen, Elina; Suur-Uski, A.-S.; Andersen, Kristian Joten; Aurvik, Ragnhild; Banerji, Ranajoy & Basyrov, Artem [Vis alle 42 forfattere av denne artikkelen] (2023). BeyondPlanck: II. CMB mapmaking through Gibbs sampling. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 675. doi: 10.1051/0004-6361/202142799. Fulltekst i vitenarkiv Vis sammendrag

  We present a Gibbs sampling solution to the mapmaking problem for cosmic microwave background (CMB) measurements that builds on existing destriping methodology. Gibbs sampling breaks the computationally heavy destriping problem into two separate steps: noise filtering and map binning. Considered as two separate steps, both are computationally much cheaper than solving the combined problem. This provides a huge performance benefit as compared to traditional methods and it allows us, for the first time, to bring the destriping baseline length to a single sample. Here, we applied the Gibbs procedure to simulated Planck 30 GHz data. We find that gaps in the time-ordered data are handled efficiently by filling them in with simulated noise as part of the Gibbs process. The Gibbs procedure yields a chain of map samples, from which we are able to compute the posterior mean as a best-estimate map. The variation in the chain provides information on the correlated residual noise, without the need to construct a full noise covariance matrix. However, if only a single maximum-likelihood frequency map estimate is required, we find that traditional conjugate gradient solvers converge much faster than a Gibbs sampler in terms of the total number of iterations. The conceptual advantages of the Gibbs sampling approach lies in statistically well-defined error propagation and systematic error correction. This methodology thus forms the conceptual basis for the mapmaking algorithm employed in the B EYOND P LANCK framework, which implements the first end-to-end Bayesian analysis pipeline for CMB observations.

• Herman, Daniel Christopher; Watson, R.A.; Andersen, Kristian Joten; Aurvik, Ragnhild; Banerji, Ranajoy & Bersanelli, M. [Vis alle 40 forfattere av denne artikkelen] (2023). BeyondPlanck: V. Minimal ADC Corrections for Planck LFI. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 675. doi: 10.1051/0004-6361/202243639. Fulltekst i vitenarkiv Vis sammendrag

  We describe the correction procedure for Analog-to-Digital Converter (ADC) differential non-linearities (DNL) adopted in the Bayesian end-to-end B EYOND P LANCK analysis framework. This method is nearly identical to that developed for the official Planck Low Frequency Instrument (LFI) Data Processing Center (DPC) analysis, and relies on the binned rms noise profile of each detector data stream. However, rather than building the correction profile directly from the raw rms profile, we first fit a Gaussian to each significant ADC-induced rms decrement, and then derive the corresponding correction model from this smooth model. The main advantage of this approach is that only samples which are significantly affected by ADC DNLs are corrected, as opposed to the DPC approach in which the correction is applied to all samples, filtering out signals not associated with ADC DNLs. The new corrections are only applied to data for which there is a clear detection of the non-linearities, and for which they perform at least comparably with the DPC corrections. Out of a total of 88 LFI data streams (sky and reference load for each of the 44 detectors) we apply the new minimal ADC corrections in 25 cases, and maintain the DPC corrections in 8 cases. All these corrections are applied to 44 or 70 GHz channels, while, as in previous analyses, none of the 30 GHz ADCs show significant evidence of non-linearity. By comparing the B EYOND P LANCK and DPC ADC correction methods, we estimate that the residual ADC uncertainty is about two orders of magnitude below the total noise of both the 44 and 70 GHz channels, and their impact on current cosmological parameter estimation is small. However, we also show that non-idealities in the ADC corrections can generate sharp stripes in the final frequency maps, and these could be important for future joint analyses with the Planck High Frequency Instrument (HFI), Wilkinson Microwave Anisotropy Probe (WMAP), or other datasets. We therefore conclude that, although the existing corrections are adequate for LFI-based cosmological parameter analysis, further work on LFI ADC corrections is still warranted.

• Andersen, Kristian Joten; Aurvik, Ragnhild; Banerji, Ranajoy; Basyrov, Artem; Bersanelli, M. & Bertocco, S. [Vis alle 44 forfattere av denne artikkelen] (2023). BeyondPlanck: I. Global Bayesian analysis of the Planck Low Frequency Instrument data. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 675. doi: 10.1051/0004-6361/202244953. Fulltekst i vitenarkiv Vis sammendrag

  We describe the B EYOND P LANCK project in terms of our motivation, methodology, and main products, and provide a guide to a set of companion papers that describe each result in more detail. Building directly on experience from ESA’s Planck mission, we implemented a complete end-to-end Bayesian analysis framework for the Planck Low Frequency Instrument (LFI) observations. The primary product is a full joint posterior distribution P ( ω  ∣  d ), where ω represents the set of all free instrumental (gain, correlated noise, bandpass, etc.), astrophysical (synchrotron, free-free, thermal dust emission, etc.), and cosmological (cosmic microwave background – CMB – map, power spectrum, etc.) parameters. Some notable advantages of this approach compared to a traditional pipeline procedure are seamless end-to-end propagation of uncertainties; accurate modeling of both astrophysical and instrumental effects in the most natural basis for each uncertain quantity; optimized computational costs with little or no need for intermediate human interaction between various analysis steps; and a complete overview of the entire analysis process within one single framework. As a practical demonstration of this framework, we focus in particular on low- ℓ CMB polarization reconstruction with Planck LFI. In this process, we identify several important new effects that have not been accounted for in previous pipelines, including gain over-smoothing and time-variable and non-1/ f correlated noise in the 30 and 44 GHz channels. Modeling and mitigating both previously known and newly discovered systematic effects, we find that all results are consistent with the ΛCDM model, and we constrained the reionization optical depth to τ  = 0.066 ± 0.013, with a low-resolution CMB-based χ 2 probability to exceed of 32%. This uncertainty is about 30% larger than the official pipelines, arising from taking a more complete instrumental model into account. The marginal CMB solar dipole amplitude is 3362.7 ± 1.4 μK, where the error bar was derived directly from the posterior distribution without the need of any ad hoc instrumental corrections. We are currently not aware of any significant unmodeled systematic effects remaining in the Planck LFI data, and, for the first time, the 44 GHz channel is fully exploited in the current analysis. We argue that this framework can play a central role in the analysis of many current and future high-sensitivity CMB experiments, including LiteBIRD, and it will serve as the computational foundation of the emerging community-wide C OSMOGLOBE effort, which aims to combine state-of-the-art radio, microwave, and submillimeter data sets into one global astrophysical model.

• Andersen, Kristian Joten; Herman, Daniel Christopher; Aurvik, Ragnhild; Banerji, Ranajoy; Basyrov, Artem & Bersanelli, M. [Vis alle 44 forfattere av denne artikkelen] (2023). BeyondPlanck: XIII. Intensity foreground sampling, degeneracies, and priors. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 675. doi: 10.1051/0004-6361/202243186. Fulltekst i vitenarkiv Vis sammendrag

  We present the intensity foreground algorithms and model employed within the B EYOND P LANCK analysis framework. The B EYOND P LANCK analysis is aimed at integrating component separation and instrumental parameter sampling within a global framework, leading to complete end-to-end error propagation in the Planck Low Frequency Instrument (LFI) data analysis. Given the scope of the B EYOND P LANCK analysis, a limited set of data is included in the component separation process, leading to foreground parameter degeneracies. In order to properly constrain the Galactic foreground parameters, we improve upon the previous Commander component separation implementation by adding a suite of algorithmic techniques. These algorithms are designed to improve the stability and computational efficiency for weakly constrained posterior distributions. These are: (1) joint foreground spectral parameter and amplitude sampling, building on ideas from M IRAMARE ; (2) component-based monopole determination; (3) joint spectral parameter and monopole sampling; and (4) application of informative spatial priors for component amplitude maps. We find that the only spectral parameter with a significant signal-to-noise ratio using the current B EYOND P LANCK data set is the peak frequency of the anomalous microwave emission component, for which we find ν p  = 25.3 ± 0.5 GHz; all others must be constrained through external priors. Future works will be aimed at integrating many more data sets into this analysis, both map and time-ordered based, thereby gradually eliminating the currently observed degeneracies in a controlled manner with respect to both instrumental systematic effects and astrophysical degeneracies. When this happens, the simple LFI-oriented data model employed in the current work will need to be generalized to account for both a richer astrophysical model and additional instrumental effects. This work will be organized within the Open Science-based C OSMOGLOBE community effort.

• Pelgrims, V.; Panopoulou, G.V.; Tassis, K.; Pavlidou, V.; Basyrov, Artem & Blinov, D. [Vis alle 23 forfattere av denne artikkelen] (2023). Starlight-polarization-based tomography of the magnetized ISM: PASIPHAE's line-of-sight inversion method. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 670. doi: 10.1051/0004-6361/202244625. Fulltekst i vitenarkiv Vis sammendrag

  We present the first Bayesian method for tomographic decomposition of the plane-of-sky orientation of the magnetic field with the use of stellar polarimetry and distance. This standalone tomographic inversion method presents an important step forward in reconstructing the magnetized interstellar medium (ISM) in three dimensions within dusty regions. We develop a model in which the polarization signal from the magnetized and dusty ISM is described by thin layers at various distances, a working assumption which should be satisfied in small-angular circular apertures. Our modeling makes it possible to infer the mean polarization (amplitude and orientation) induced by individual dusty clouds and to account for the turbulence-induced scatter in a generic way. We present a likelihood function that explicitly accounts for uncertainties in polarization and parallax. We develop a framework for reconstructing the magnetized ISM through the maximization of the log-likelihood using a nested sampling method. We test our Bayesian inversion method on mock data, representative of the high Galactic latitude sky, taking into account realistic uncertainties from Gaia and as expected for the optical polarization survey P ASIPHAE according to the currently planned observing strategy. We demonstrate that our method is effective at recovering the cloud properties as soon as the polarization induced by a cloud to its background stars is higher than ~0.1% for the adopted survey exposure time and level of systematic uncertainty. The larger the induced polarization is, the better the method’s performance, and the lower the number of required stars. Our method makes it possible to recover not only the mean polarization properties but also to characterize the intrinsic scatter, thus creating new ways to characterize ISM turbulence and the magnetic field strength. Finally, we apply our method to an existing data set of starlight polarization with known line-of-sight decomposition, demonstrating agreement with previous results and an improved quantification of uncertainties in cloud properties.

• Ihle, Håvard Tveit; Bersanelli, M.; Franceschet, C.; Gjerløw, Eirik; Andersen, Kristian Joten & Aurvik, Ragnhild [Vis alle 41 forfattere av denne artikkelen] (2023). BeyondPlanck: VI. Noise characterization and modeling. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 675. doi: 10.1051/0004-6361/202243619. Fulltekst i vitenarkiv Vis sammendrag

  We present a Bayesian method for estimating instrumental noise parameters and propagating noise uncertainties within the global BEYONDPLANCK Gibbs sampling framework, which we applied to Planck Low Frequency Instrument (LFI) time-ordered data. Following previous works in the literature, we initially adopted a 1/f model for the noise power spectral density (PSD), but we found the need for an additional lognormal component in the noise model in the 30 and 44 GHz bands. We implemented an optimal Wiener-filter (or constrained realization) gap-filling procedure to account for masked data. We then used this procedure to both estimate the gapless correlated noise in the time-domain, ncorr, and to sample the noise PSD parameters, ξn = {σ0, fknee, α, Ap}. In contrast to previous Planck analyses, we assumed piecewise stationary noise only within each pointing period (PID), and not throughout the full mission, but we adopted the LFI Data Processing Center results as priors on α and fknee. We generally found best-fit correlated noise parameters that are mostly consistent with previous results, with a few notable exceptions. However, a detailed inspection of the time-dependent results has revealed many important findings. First and foremost, we find strong evidence for statistically significant temporal variations in all noise PSD parameters, many of which are directly correlated with satellite housekeeping data. Second, while the simple 1/f model appears to be an excellent fit for the LFI 70 GHz channel, there is evidence for additional correlated noise that is not described by a 1/f model in the 30 and 44 GHz channels, including within the primary science frequency range of 0.1–1 Hz. In general, most 30 and 44 GHz channels exhibit deviations from 1/f at the 2–3σ level in each one-hour pointing period, motivating the addition of the lognormal noise component for these bands. For certain periods of time, we also find evidence of strong common mode noise fluctuations across the entire focal plane. Overall, we conclude that a simple 1/f profile is not adequate for obtaining a full characterization of the Planck LFI noise, even when fitted hour-by-hour, and a more general model is required. These findings have important implications for large-scale CMB polarization reconstruction with the Planck LFI data and the current work is a first attempt at understanding and mitigating these issues.

• Svalheim, Trygve Leithe; Zonca, A.; Andersen, Kristian Joten; Aurvik, Ragnhild; Banerji, Ranajoy & Bersanelli, M. [Vis alle 39 forfattere av denne artikkelen] (2023). BeyondPlanck: IX. Bandpass and beam leakage corrections. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 675. doi: 10.1051/0004-6361/202243080. Fulltekst i vitenarkiv Vis sammendrag

  We discuss the treatment of bandpass and beam leakage corrections in the Bayesian B EYOND P LANCK cosmic microwave background (CMB) analysis pipeline as applied to the Planck LFI measurements. As a preparatory step, we first applied three corrections to the nominal LFI bandpass profiles, including the removal of a known systematic effect in the ground measuring equipment at 61 GHz, along with a smoothing of standing wave ripples and edge regularization. The main net impact of these modifications is an overall shift in the 70 GHz bandpass of +0.6 GHz. We argue that any analysis of LFI data products, either from Planck or B EYOND P LANCK , should use these new bandpasses. In addition, we fit a single free bandpass parameter for each radiometer of the form Δ i  = Δ 0  +  δ i , where Δ 0 represents an absolute frequency shift per frequency band and δ i is a relative shift per detector. The absolute correction is only fitted at 30 GHz, with a full χ 2 -based likelihood, resulting in a correction of Δ 30  = 0.24 ± 0.03 GHz. The relative corrections were fitted using a spurious map approach that is fundamentally similar to the method pioneered by the WMAP team, but excluding the introduction of many additional degrees of freedom. All the bandpass parameters were sampled using a standard Metropolis sampler within the main B EYOND P LANCK Gibbs chain and the bandpass uncertainties were thus propagated to all other data products in the analysis. In summary, we find that our bandpass model significantly reduces leakage effects. For beam leakage corrections, we adopted the official Planck LFI beam estimates without any additional degrees of freedom and we only marginalized over the underlying sky model. We note that this is the first time that leakage from beam mismatch has been included for Planck LFI maps.

• Ade, Peter A.R.; Amiri, M.; Benton, S.J.; Bergman, A.S.; Bihary, R. & Bock, J.J. [Vis alle 70 forfattere av denne artikkelen] (2022). A Constraint on Primordial B-modes from the First Flight of the Spider Balloon-borne Telescope. The Astrophysical Journal (ApJ). ISSN 0004-637X. 927(2). doi: 10.3847/1538-4357/ac20df. Fulltekst i vitenarkiv Vis sammendrag

  We present the first linear polarization measurements from the 2015 long-duration balloon flight of Spider, which is an experiment that is designed to map the polarization of the cosmic microwave background (CMB) on degree angular scales. The results from these measurements include maps and angular power spectra from observations of 4.8% of the sky at 95 and 150 GHz, along with the results of internal consistency tests on these data. While the polarized CMB anisotropy from primordial density perturbations is the dominant signal in this region of sky, Galactic dust emission is also detected with high significance. Galactic synchrotron emission is found to be negligible in the Spider bands. We employ two independent foreground-removal techniques to explore the sensitivity of the cosmological result to the assumptions made by each. The primary method uses a dust template derived from Planck data to subtract the Galactic dust signal. A second approach, which constitutes a joint analysis of Spider and Planck data in the harmonic domain, assumes a modified-blackbody model for the spectral energy distribution of the dust with no constraint on its spatial morphology. Using a likelihood that jointly samples the template amplitude and r parameter space, we derive 95% upper limits on the primordial tensor-to-scalar ratio from Feldman–Cousins and Bayesian constructions, finding r < 0.11 and r < 0.19, respectively. Roughly half the uncertainty in r derives from noise associated with the template subtraction. New data at 280 GHz from Spider's second flight will complement the Planck polarization maps, providing powerful measurements of the polarized Galactic dust emission.

• Maharana, Siddharth; Anche, Ranya M.; Ramaprakash, Anamparambu N.; Joshi, Bhushan; Basyrov, Artem & Blinov, Dmitry [Vis alle 25 forfattere av denne artikkelen] (2022). WALOP-South: a four-camera one-shot imaging polarimeter for PASIPHAE survey. Paper II – polarimetric modeling and calibration. Journal of Astronomical Telescopes, Instruments, and Systems (JATIS). ISSN 2329-4124. 8(3). doi: 10.1117/1.JATIS.8.3.038004. Fulltekst i vitenarkiv Vis sammendrag

  The Wide-Area Linear Optical Polarimeter (WALOP)-South instrument is an upcoming wide-field and high accuracy optical polarimeter to be used as a survey instrument for carrying out the Polar-Areas Stellar Imaging in Polarization High-Accuracy Experiment program. Designed to operate as a one-shot four-channel and four-camera imaging polarimeter, it will have a field of view of 35 × 35 arcminutes and will measure the Stokes parameters I, q, and u in a single exposure in the Sloan Digital Sky Survey-r broadband filter. The design goal for the instrument is to achieve an overall polarimetric measurement accuracy of 0.1% over the entire field of view. We present here the complete polarimetric modeling of the instrument, characterizing the amount and sources of instrumental polarization. To accurately retrieve the real Stokes parameters of a source from the measured values, we have developed a calibration method for the instrument. Using this calibration method and simulated data, we demonstrate how to correct for instrumental polarization and obtain 0.1% accuracy in degree of polarization, p. In addition, we tested and validated the calibration method by implementing it on a table-top WALOP like test-bed polarimeter in the laboratory.

• Anche, Ramya M.; Maharana, Siddharth; Ramaprakash, Anamparambu N.; Khodade, Pravin; Modi, Deepa & Rajarshi, Chaitanya [Vis alle 24 forfattere av denne artikkelen] (2022). Stress-induced birefringence in the lenses of Wide-Area Linear Optical Polarimeter-South. Proceedings of SPIE, the International Society for Optical Engineering. ISSN 0277-786X. 12188. doi: 10.1117/12.2629515. Fulltekst i vitenarkiv Vis sammendrag

  Two unique wide-field and high-accuracy polarimeters named WALOP (Wide-Area Linear Optical Polarimeter)- North and WALOP-South are currently under development at the Inter-University Center for Astronomy and Astrophysics (IUCAA), India, to create a large area optical polarization map of the sky for the upcoming PASIPHAE sky survey. These instruments are designed to achieve a linear polarimetric measurement accuracy of 0.1% across a field of view (FoV) of 30×30 arcminutes. The WALOP-South instrument will be installed first on a 1 m telescope at the Sutherland Observatory, where the temperatures during the night can vary between 10 to -5°C. These temperature variations and the instrument’s pointing to various non-zenithal positions in the sky can introduce stress birefringence in the lenses, leading to time-varying instrumental polarization. This work estimates stress-induced birefringence due to thermal, and gravity stresses on WALOP-South lenses. Using the optomechanical model of the WALOP-South, we carried out Finite Element Analysis (FEA) simulations in SolidWorks software to estimate the stresses for various scenarios of temperature, telescope pointing airmass, and lens mount material (aluminum and titanium). Further, we use the stress tensor analysis to estimate the principal stresses and their directions and consequent birefringence and retardance introduced in the lenses. The stressinduced birefringence will change the optical path length for orthogonal polarization states of the beam passing through the lenses and introduce phase retardation. Overall, with the lens mount design of the instrument, we find that the retardation and consequent instrumental polarization will be within the instrumental accuracy requirements. Additionally, the stress birefringence is found to be higher for aluminum compared to titanium mounts. We further incorporated this retardance in the instrument Mueller matrix estimation to understand its effects on the polarization measurements.

• Cleary, Kieran A.; Borowska, Jowita; Breysse, Patrick C.; Catha, Morgan; Chung, Dongwoo T. & Church, Sarah E. [Vis alle 43 forfattere av denne artikkelen] (2022). COMAP Early Science. I. Overview. The Astrophysical Journal (ApJ). ISSN 0004-637X. 933(2). doi: 10.3847/1538-4357/ac63cc. Fulltekst i vitenarkiv Vis sammendrag

  The CO Mapping Array Project (COMAP) aims to use line-intensity mapping of carbon monoxide (CO) to trace the distribution and global properties of galaxies over cosmic time, back to the Epoch of Reionization (EoR). To validate the technologies and techniques needed for this goal, a Pathfinder instrument has been constructed and fielded. Sensitive to CO(1–0) emission from z = 2.4–3.4 and a fainter contribution from CO(2–1) at z = 6–8, the Pathfinder is surveying 12 deg2 in a 5 yr observing campaign to detect the CO signal from z ∼ 3. Using data from the first 13 months of observing, we estimate PCO(k) = −2.7 ± 1.7 × 104 μK2 Mpc3 on scales k = 0.051 −0.62 Mpc−1, the first direct three-dimensional constraint on the clustering component of the CO(1–0) power spectrum. Based on these observations alone, we obtain a constraint on the amplitude of the clustering component (the squared mean CO line temperature bias product) of ${\left\langle {Tb}\right\rangle }^{2}\lt 49$ μK2, nearly an order-of-magnitude improvement on the previous best measurement. These constraints allow us to rule out two models from the literature. We forecast a detection of the power spectrum after 5 yr with signal-to-noise ratio (S/N) 9–17. Cross-correlation with an overlapping galaxy survey will yield a detection of the CO–galaxy power spectrum with S/N of 19. We are also conducting a 30 GHz survey of the Galactic plane and present a preliminary map. Looking to the future of COMAP, we examine the prospects for future phases of the experiment to detect and characterize the CO signal from the EoR.

• Vielva, P.; Martínez-González, E.; Casas, F.J.; Matsumura, T.; Henrot-Versillé, S. & Komatsu, E. [Vis alle 71 forfattere av denne artikkelen] (2022). Polarization angle requirements for CMB B-mode experiments. Application to the LiteBIRD satellite. Journal of Cosmology and Astroparticle Physics (JCAP). 2022(4). doi: 10.1088/1475-7516/2022/04/029. Fulltekst i vitenarkiv
• Foss, Marie Kristine; Ihle, Håvard Tveit; Borowska, Jowita; Cleary, Kieran A.; Eriksen, Hans Kristian Kamfjord & Harper, Stuart E. [Vis alle 33 forfattere av denne artikkelen] (2022). COMAP Early Science. III. CO Data Processing. The Astrophysical Journal (ApJ). ISSN 0004-637X. 933(2). doi: 10.3847/1538-4357/ac63ca. Fulltekst i vitenarkiv Vis sammendrag

  We describe the first-season CO Mapping Array Project (COMAP) analysis pipeline that converts raw detector readouts to calibrated sky maps. This pipeline implements four main steps: gain calibration, filtering, data selection, and mapmaking. Absolute gain calibration relies on a combination of instrumental and astrophysical sources, while relative gain calibration exploits real-time total-power variations. High-efficiency filtering is achieved through spectroscopic common-mode rejection within and across receivers, resulting in nearly uncorrelated white noise within single-frequency channels. Consequently, near-optimal but biased maps are produced by binning the filtered time stream into pixelized maps; the corresponding signal bias transfer function is estimated through simulations. Data selection is performed automatically through a series of goodness-of-fit statistics, including χ2 and multiscale correlation tests. Applying this pipeline to the first-season COMAP data, we produce a data set with very low levels of correlated noise. We find that one of our two scanning strategies (the Lissajous type) is sensitive to residual instrumental systematics. As a result, we no longer use this type of scan and exclude data taken this way from our Season 1 power spectrum estimates. We perform a careful analysis of our data processing and observing efficiencies and take account of planned improvements to estimate our future performance. Power spectrum results derived from the first-season COMAP maps are presented and discussed in companion papers.

• Lamb, James W.; Cleary, Kieran A.; Woody, David P.; Catha, Morgan; Chung, Dongwoo T. & Gundersen, Joshua Ott [Vis alle 36 forfattere av denne artikkelen] (2022). COMAP Early Science. II. Pathfinder Instrument. The Astrophysical Journal (ApJ). ISSN 0004-637X. 933(2). doi: 10.3847/1538-4357/ac63c6. Fulltekst i vitenarkiv Vis sammendrag

  Line intensity mapping (LIM) is a new technique for tracing the global properties of galaxies over cosmic time. Detection of the very faint signals from redshifted carbon monoxide (CO), a tracer of star formation, pushes the limits of what is feasible with a total-power instrument. The CO Mapping Project Pathfinder is a first-generation instrument aiming to prove the concept and develop the technology for future experiments, as well as delivering early science products. With 19 receiver channels in a hexagonal focal plane arrangement on a 10.4 m antenna and an instantaneous 26–34 GHz frequency range with 2 MHz resolution, it is ideally suited to measuring CO (J = 1–0) from z ∼ 3. In this paper we discuss strategies for designing and building the Pathfinder and the challenges that were encountered. The design of the instrument prioritized LIM requirements over those of ancillary science. After a couple of years of operation, the instrument is well understood, and the first year of data is already yielding useful science results. Experience with this Pathfinder will guide the design of the next generations of experiments.

• Rennie, Thomas J.; Harper, Stuart E.; Dickinson, Clive; Philip, Liju; Cleary, Kieran A. & Bond, Richard J. [Vis alle 32 forfattere av denne artikkelen] (2022). COMAP Early Science. VI. A First Look at the COMAP Galactic Plane Survey. The Astrophysical Journal (ApJ). ISSN 0004-637X. 933(2). doi: 10.3847/1538-4357/ac63c8. Fulltekst i vitenarkiv Vis sammendrag

  We present early results from the CO Mapping Array Project (COMAP) Galactic Plane Survey conducted between 2019 June and 2021 April, spanning 20° < ℓ < 40° in Galactic longitude and ∣b∣ < 1fdg5 in Galactic latitude with an angular resolution of 4farcm5. We present initial results from the first part of the survey, including the diffuse emission and spectral energy distributions of H ii regions and supernova remnants (SNRs). Using low- and high-frequency surveys to constrain free–free and thermal dust emission contributions, we find evidence of excess flux density at 30 GHz in six regions, which we interpret as anomalous microwave emission. Furthermore we model ultracompact H ii contributions using data from the 5 GHz CORNISH catalog and reject these as the cause of the 30 GHz excess. Six known SNRs are detected at 30 GHz, and we measure spectral indices consistent with the literature or show evidence of steepening. The flux density of the SNR W44 at 30 GHz is consistent with a power-law extrapolation from lower frequencies with no indication of spectral steepening in contrast with recent results from the Sardinia Radio Telescope. We also extract five hydrogen radio recombination lines (RRLs) to map the warm ionized gas, which can be used to estimate electron temperatures or to constrain continuum free–free emission. The full COMAP Galactic Plane Survey, to be released in 2023/2024, will span ℓ ∼ 20°–220° and will be the first large-scale radio continuum and RRL survey at 30 GHz with 4farcm5 resolution.

• Breysse, Patrick C.; Chung, Dongwoo T.; Cleary, Kieran A.; Ihle, Håvard Tveit; Padmanabhan, Hamsa & Silva, Marta Bruno [Vis alle 32 forfattere av denne artikkelen] (2022). COMAP Early Science. VII. Prospects for CO Intensity Mapping at Reionization. The Astrophysical Journal (ApJ). ISSN 0004-637X. 933(2). doi: 10.3847/1538-4357/ac63c9. Fulltekst i vitenarkiv Vis sammendrag

  We introduce COMAP-EoR, the next generation of the Carbon Monoxide Mapping Array Project aimed at extending CO intensity mapping to the Epoch of Reionization. COMAP-EoR supplements the existing 30 GHz COMAP Pathfinder with two additional 30 GHz instruments and a new 16 GHz receiver. This combination of frequencies will be able to simultaneously map CO(1–0) and CO(2–1) at reionization redshifts (z ∼ 5–8) in addition to providing a significant boost to the z ∼ 3 sensitivity of the Pathfinder. We examine a set of existing models of the EoR CO signal, and find power spectra spanning several orders of magnitude, highlighting our extreme ignorance about this period of cosmic history and the value of the COMAP-EoR measurement. We carry out the most detailed forecast to date of an intensity mapping cross correlation, and find that five out of the six models we consider yield signal to noise ratios (S/Ns) ≳ 20 for COMAP-EoR, with the brightest reaching a S/N above 400. We show that, for these models, COMAP-EoR can make a detailed measurement of the cosmic molecular gas history from z ∼ 2–8, as well as probe the population of faint, star-forming galaxies predicted by these models to be undetectable by traditional surveys. We show that, for the single model that does not predict numerous faint emitters, a COMAP-EoR-type measurement is required to rule out their existence. We briefly explore prospects for a third-generation Expanded Reionization Array (COMAP-ERA) capable of detecting the faintest models and characterizing the brightest signals in extreme detail.

• Diego-Palazuelos, P.; Eskilt, Johannes Røsok; Minami, Y.; Tristram, M.; Sullivan, R. M. & Banday, A. J. [Vis alle 15 forfattere av denne artikkelen] (2022). Cosmic Birefringence from the Planck Data Release 4. Physical Review Letters. ISSN 0031-9007. 128(9). doi: 10.1103/PhysRevLett.128.091302. Fulltekst i vitenarkiv Vis sammendrag

  We search for the signature of parity-violating physics in the cosmic microwave background, called cosmic birefringence, using the Planck data release 4. We initially find a birefringence angle of β=0.30°±0.11° (68% C.L.) for nearly full-sky data. The values of β decrease as we enlarge the Galactic mask, which can be interpreted as the effect of polarized foreground emission. Two independent ways to model this effect are used to mitigate the systematic impact on β for different sky fractions. We choose not to assign cosmological significance to the measured value of β until we improve our knowledge of the foreground polarization.

• Chung, Dongwoo T.; Breysse, Patrick C.; Cleary, Kieran A.; Ihle, Håvard Tveit; Padmanabhan, Hamsa & Silva, Marta Bruno [Vis alle 37 forfattere av denne artikkelen] (2022). COMAP Early Science. V. Constraints and Forecasts at z ∼3. The Astrophysical Journal (ApJ). ISSN 0004-637X. 933(2). doi: 10.3847/1538-4357/ac63c7. Fulltekst i vitenarkiv Vis sammendrag

  We present the current state of models for the z ∼ 3 carbon monoxide (CO) line intensity signal targeted by the CO Mapping Array Project (COMAP) Pathfinder in the context of its early science results. Our fiducial model, relating dark matter halo properties to CO luminosities, informs parameter priors with empirical models of the galaxy–halo connection and previous CO (1–0) observations. The Pathfinder early science data spanning wavenumbers k = 0.051–0.62 Mpc−1 represent the first direct 3D constraint on the clustering component of the CO (1–0) power spectrum. Our 95% upper limit on the redshift-space clustering amplitude Aclust ≲ 70 μK2 greatly improves on the indirect upper limit of 420 μK2 reported from the CO Power Spectrum Survey (COPSS) measurement at k ∼ 1 Mpc−1. The COMAP limit excludes a subset of models from previous literature and constrains interpretation of the COPSS results, demonstrating the complementary nature of COMAP and interferometric CO surveys. Using line bias expectations from our priors, we also constrain the squared mean line intensity–bias product, ${\left\langle {Tb}\right\rangle }_{2}$ ≲ 50 μK2, and the cosmic molecular gas density, ρH2 < 2.5 × 108 M⊙ Mpc−3 (95% upper limits). Based on early instrument performance and our current CO signal estimates, we forecast that the 5 yr Pathfinder campaign will detect the CO power spectrum with overall signal-to-noise ratio of 9–17. Between then and now, we also expect to detect the CO–galaxy cross-spectrum using overlapping galaxy survey data, enabling enhanced inferences of cosmic star formation and galaxy evolution history.

• Hasebe, T.; Ade, P.A.R.; Adler, A.; Allys, E.; Alonso, D. & Arnold, K. [Vis alle 281 forfattere av denne artikkelen] (2022). Sensitivity Modeling for LiteBIRD. Journal of Low Temperature Physics. ISSN 0022-2291. doi: 10.1007/s10909-022-02921-7. Fulltekst i vitenarkiv
• Tristram, M.; Banday, A.J.; Górski, K.M.; Keskitalo, R.; Lawrence, C.R. & Andersen, Kristian Joten [Vis alle 17 forfattere av denne artikkelen] (2022). Improved limits on the tensor-to-scalar ratio using BICEP and Planck data. Physical Review D. ISSN 2470-0010. 105(8). doi: 10.1103/PhysRevD.105.083524. Fulltekst i vitenarkiv Vis sammendrag

  We present constraints on the tensor-to-scalar ratio r using a combination of BICEP/Keck 2018 (BK18) and Planck PR4 data allowing us to fit for r consistently with the six parameters of the ΛCDM model. We discuss the sensitivity of constraints on r to uncertainties in the ΛCDM parameters as defined by the Planck data. In particular, we are able to derive a constraint on the reionization optical depth τ and thus propagate its uncertainty into the posterior distribution for r. While Planck sensitivity to r is slightly lower than the current ground-based measurements, the combination of Planck with BK18 and baryon-acoustic-oscillation data yields results consistent with r=0 and tightens the constraint to r<0.032 at 95% confidence.

• Filippini, J.P.; Gambrel, A.E.; Rahlin, A.S.; Young, E.Y.; Ade, P.A.R. & Amiri, M. [Vis alle 70 forfattere av denne artikkelen] (2022). In-Flight Gain Monitoring of SPIDER’s Transition-Edge Sensor Arrays. Journal of Low Temperature Physics. ISSN 0022-2291. 209(3-4), s. 649–657. doi: 10.1007/s10909-022-02729-5. Fulltekst i vitenarkiv
• Ihle, Håvard Tveit; Borowska, Jowita; Cleary, Kieran A.; Eriksen, Hans Kristian Kamfjord; Foss, Marie Kristine & Harper, Stuart E. [Vis alle 33 forfattere av denne artikkelen] (2022). COMAP Early Science. IV. Power Spectrum Methodology and Results. The Astrophysical Journal (ApJ). ISSN 0004-637X. 933(2). doi: 10.3847/1538-4357/ac63c5. Fulltekst i vitenarkiv Vis sammendrag

  We present the power spectrum methodology used for the first-season COMAP analysis, and assess the quality of the current data set. The main results are derived through the Feed–Feed Pseudo-Cross-Spectrum (FPXS) method, which is a robust estimator with respect to both noise modeling errors and experimental systematics. We use effective transfer functions to take into account the effects of instrumental beam smoothing and various filter operations applied during the low-level data processing. The power spectra estimated in this way have allowed us to identify a systematic error associated with one of our two scanning strategies, believed to be due to residual ground or atmospheric contamination. We omit these data from our analysis and no longer use this scanning technique for observations. We present the power spectra from our first season of observing, and demonstrate that the uncertainties are integrating as expected for uncorrelated noise, with any residual systematics suppressed to a level below the noise. Using the FPXS method, and combining data on scales k = 0.051–0.62 Mpc−1, we estimate PCO(k) = −2. 7 ± 1.7 × 104 μK2 Mpc3, the first direct 3D constraint on the clustering component of the CO(1–0) power spectrum in the literature.

• Hubmayr, J.; Ade, P.A.R.; Adler, A.; Allys, E.; Alonso, D. & Arnold, K. [Vis alle 320 forfattere av denne artikkelen] (2022). Optical Characterization of OMT-Coupled TES Bolometers for LiteBIRD. Journal of Low Temperature Physics. ISSN 0022-2291. 209(3-4), s. 396–408. doi: 10.1007/s10909-022-02808-7. Fulltekst i vitenarkiv
• Leung, Jason S.-Y.; Hartley, J.; Nagy, J.M.; Netterfield, C.B.; Shariff, J.A. & Ade, P.A.R. [Vis alle 70 forfattere av denne artikkelen] (2022). A Simulation-based Method for Correcting Mode Coupling in CMB Angular Power Spectra. The Astrophysical Journal (ApJ). ISSN 0004-637X. 928(2). doi: 10.3847/1538-4357/ac562f. Fulltekst i vitenarkiv Vis sammendrag

  Modern cosmic microwave background (CMB) analysis pipelines regularly employ complex time-domain filters, beam models, masking, and other techniques during the production of sky maps and their corresponding angular power spectra. However, these processes can generate couplings between multipoles from the same spectrum and from different spectra, in addition to the typical power attenuation. Within the context of pseudo-Cℓ based, MASTER-style analyses, the net effect of the time-domain filtering is commonly approximated by a multiplicative transfer function, Fℓ, that can fail to capture mode mixing and is dependent on the spectrum of the signal. To address these shortcomings, we have developed a simulation-based spectral correction approach that constructs a two-dimensional transfer matrix, ${J}_{{\ell }{\ell }^{\prime} }$, which contains information about mode mixing in addition to mode attenuation. We demonstrate the application of this approach on data from the first flight of the Spider balloon-borne CMB experiment.

• Chung, Dongwoo T.; Breysse, Patrick C.; Ihle, Håvard Tveit; Padmanabhan, Hamsa; Silva, Marta Bruno & Bond, John Richard [Vis alle 18 forfattere av denne artikkelen] (2021). A Model of Spectral Line Broadening in Signal Forecasts for Line-intensity Mapping Experiments. The Astrophysical Journal (ApJ). ISSN 0004-637X. 923(2). doi: 10.3847/1538-4357/ac2a35. Fulltekst i vitenarkiv
• Fuskeland, Unni; Andersen, Kristian Joten; Aurlien, Ragnhild; Banerji, Ranajoy; Brilenkov, Maksym & Eriksen, Hans Kristian Kamfjord [Vis alle 11 forfattere av denne artikkelen] (2021). Constraints on the spectral index of polarized synchrotron emission from WMAP and Faraday-corrected S-PASS data. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 646. doi: 10.1051/0004-6361/202037629. Fulltekst i vitenarkiv Vis sammendrag

  We constrain the spectral index of polarized synchrotron emission, β s , by correlating the recently released 2.3 GHz S -Band Polarization All Sky Survey ( S -PASS) data with the 23 GHz 9-year Wilkinson Microwave Anisotropy Probe (WMAP) sky maps. We subdivide the S-PASS field, which covers the southern ecliptic hemisphere, into 95 15° ×15° regions and estimate the spectral index of polarized synchrotron emission within each region using a simple but robust T – T plot technique. Three different versions of the S-PASS data are considered, corresponding to: no correction for Faraday rotation; Faraday correction based on the rotation measure model presented by the S-PASS team; or Faraday correction based on a rotation measure model presented by Hutschenreuter and Enßlin. We find that the correlation between S-PASS and WMAP is strongest when applying the S-PASS model. Adopting this correction model, we find that the mean spectral index of polarized synchrotron emission gradually steepens from β s  ≈ −2.8 at low Galactic latitudes to β s  ≈ −3.3 at high Galactic latitudes, in good agreement with previously published results. The flat spectral index at the low Galactic latitudes is likely partly due to depolarization effects. Finally, we consider two special cases defined by the BICEP2 and SPIDER fields and obtain mean estimates of β BICEP2  = −3.22 ± 0.06 and β SPIDER  = −3.21 ± 0.03, respectively. Adopting the bandpass filtered WMAP 23 GHz sky map to only include angular scales between 2° and 10° as a spatial template, we constrain the root-mean-square synchrotron polarization amplitude to be less than 0.03  μ K (0.009  μ K) at 90 GHz (150 GHz) for the BICEP2 field, corresponding roughly to a tensor-to-scalar ratio of r  ≲ 0.02 ( r  ≲ 0.005). Very similar constraints are obtained for the SPIDER field. A comparison with a similar analysis performed in the 23–33 GHz range suggests a flattening of about Δ β s  ∼ 0.1 ± 0.2 from low to higher frequencies, but with no statistical significance due to high uncertainties.

• Maharana, Siddharth; Kypriotakis, John A.; Ramaprakash, Anamparambu N.; Rajarshi, Chaitanya; Anche, Ranya M. & Shrish, Shrish [Vis alle 20 forfattere av denne artikkelen] (2021). WALOP-South: a four-camera one-shot imaging polarimeter for PASIPHAE survey. Paper I—optical design. Journal of Astronomical Telescopes, Instruments, and Systems (JATIS). ISSN 2329-4124. 7(1). doi: 10.1117/1.JATIS.7.1.014004. Fulltekst i vitenarkiv Vis sammendrag

  The Wide-Area Linear Optical Polarimeter (WALOP)-South instrument will be mounted on the 1-m South African Astronomical Observatory telescope in South Africa as part of the Polar-Areas Stellar Imaging Polarization High Accuracy Experiment (PASIPHAE) program to carry out a linear imaging polarization survey of the Galactic polar regions in the optical band. Designed to achieve polarimetric sensitivity of 0.05% across a 35  ×  35  arc min field of view (FOV), it will be capable of measuring the Stokes parameters I, q, and u in a single exposure in the R broadband and narrowband filters between 0.5 to 0.7  μm. For each measurement, four images of the full field corresponding to linear polarization angles of 0 deg, 45 deg, 90 deg, and 135 deg in the instrument coordinate system will be created on four detectors from which the Stokes parameters can be found using differential photometry. In designing the optical system, major challenges included correcting for the dispersion introduced by large split angle Wollaston prisms used as analysers and other aberrations from the entire field to obtain imaging quality point spread function (PSF) at the detector. We present the optical design of the WALOP-South instrument which overcomes these challenges and delivers near seeing limited PSFs for the entire FOV.

• Pelgrims, Vincent; Clark, S. E.; Hensley, B. S.; Panopoulou, Georgia V.; Pavlidou, Vasiliki & Tassis, Konstantinos [Vis alle 8 forfattere av denne artikkelen] (2021). Evidence for line-of-sight frequency decorrelation of polarized dust emission in Planck data. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 647. doi: 10.1051/0004-6361/202040218. Fulltekst i vitenarkiv Vis sammendrag

  If a single line of sight (LOS) intercepts multiple dust clouds with different spectral energy distributions and magnetic field orientations, then the frequency scaling of each of the Stokes Q and U parameters of the thermal dust emission may be different, a phenomenon we refer to as LOS frequency decorrelation. We present first evidence for LOS frequency decorrelation in Planck data using independent measurements of neutral-hydrogen (H I ) emission to probe the 3D structure of the magnetized interstellar medium (ISM). We use H I -based measurements of the number of clouds per LOS and the magnetic field orientation in each cloud to select two sets of sightlines: (i) a target sample of pixels that are likely to exhibit LOS frequency decorrelation and (ii) a control sample of pixels that lack complex LOS structure. We test the null hypothesis that LOS frequency decorrelation is not detectable in Planck 353 and 217 GHz polarization data at high Galactic latitudes. We reject the null hypothesis at high significance based on data that show that the combined effect of polarization angle variation with frequency and depolarization are detected in the target sample. This detection is robust against the choice of cosmic microwave background (CMB) map and map-making pipeline. The observed change in polarization angle due to LOS frequency decorrelation is detectable above the Planck noise level. The probability that the detected effect is due to noise alone ranges from 5 × 10 −2 to 4 × 10 −7 , depending on the CMB subtraction algorithm and treatment of residual systematic errors; correcting for residual systematic errors consistently increases the significance of the effect. Within the target sample, the LOS decorrelation effect is stronger for sightlines with more misaligned magnetic fields, as expected. With our sample, we estimate that an intrinsic variation of ~15% in the ratio of 353 to 217 GHz polarized emission between clouds is sufficient to reproduce the measured effect. Our finding underlines the importance of ongoing studies to map the three-dimensional structure of the magnetized and dusty ISM that could ultimately help component separation methods to account for frequency decorrelation effects in CMB polarization studies.

• Gambrel, Anne E.; Rahlin, Alexandra S.; Song, X.; Contaldi, Carlo R.; Ade, Peter A.R. & Amiri, M. [Vis alle 67 forfattere av denne artikkelen] (2021). The XFaster Power Spectrum and Likelihood Estimator for the Analysis of Cosmic Microwave Background Maps. The Astrophysical Journal (ApJ). ISSN 0004-637X. 922(2). doi: 10.3847/1538-4357/ac230b. Fulltekst i vitenarkiv
• Tristram, M.; Banday, A. J.; Górski, Krzysztof M.; Keskitalo, R.; Lawrence, C. R. & Andersen, Kristian Joten [Vis alle 17 forfattere av denne artikkelen] (2021). Planck constraints on the tensor-to-scalar ratio. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 647. doi: 10.1051/0004-6361/202039585. Fulltekst i vitenarkiv Vis sammendrag

  We present constraints on the tensor-to-scalar ratio r using Planck data. We use the latest release of Planck maps, processed with the NPIPE code, which produces calibrated frequency maps in temperature and polarisation for all Planck channels from 30 GHz to 857 GHz using the same pipeline. We computed constraints on r using the BB angular power spectrum, and we also discuss constraints coming from the TT spectrum. Given Planck ’s noise level, the TT spectrum gives constraints on r that are cosmic-variance limited (with σ r  = 0.093), but we show that the marginalised posterior peaks towards negative values of r at about the 1.2 σ level. We derived Planck constraints using the BB power spectrum at both large angular scales (the ‘reionisation bump’) and intermediate angular scales (the ‘recombination bump’) from ℓ = 2 to 150 and find a stronger constraint than that from TT , with σ r  = 0.069. The Planck BB spectrum shows no systematic bias and is compatible with zero, given both the statistical noise and the systematic uncertainties. The likelihood analysis using B modes yields the constraint r  &lt; 0.158 at 95% confidence using more than 50% of the sky. This upper limit tightens to r  &lt; 0.069 when Planck EE , BB , and EB power spectra are combined consistently, and it tightens further to r  &lt; 0.056 when the Planck TT power spectrum is included in the combination. Finally, combining Planck with BICEP2/Keck 2015 data yields an upper limit of r  &lt; 0.044.

• Cheghasiahi, Yashar Akrami; Argüeso, F.; Ashdown, M.; Aumont, J.; Baccigalupi, Carlo & Ballardini, M. [Vis alle 150 forfattere av denne artikkelen] (2020). Planck 2018 results: II. Low Frequency Instrument data processing. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 641. doi: 10.1051/0004-6361/201833293. Fulltekst i vitenarkiv Vis sammendrag

  We present a final description of the data-processing pipeline for the Planck Low Frequency Instrument (LFI), implemented for the 2018 data release. Several improvements have been made with respect to the previous release, especially in the calibration process and in the correction of instrumental features such as the effects of nonlinearity in the response of the analogue-to-digital converters. We provide a brief pedagogical introduction to the complete pipeline, as well as a detailed description of the important changes implemented. Self-consistency of the pipeline is demonstrated using dedicated simulations and null tests. We present the final version of the LFI full sky maps at 30, 44, and 70 GHz, both in temperature and polarization, together with a refined estimate of the solar dipole and a final assessment of the main LFI instrumental parameters.

• Aghanim, Nabila; Cheghasiahi, Yashar Akrami; Ashdown, M.; Aumont, J.; Baccigalupi, Carlo & Ballardini, M. [Vis alle 158 forfattere av denne artikkelen] (2020). Planck 2018 results: VIII. Gravitational lensing. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 641. doi: 10.1051/0004-6361/201833886. Fulltekst i vitenarkiv Vis sammendrag

  We present measurements of the cosmic microwave background (CMB) lensing potential using the final Planck 2018 temperature and polarization data. Using polarization maps filtered to account for the noise anisotropy, we increase the significance of the detection of lensing in the polarization maps from 5 σ to 9 σ . Combined with temperature, lensing is detected at 40 σ . We present an extensive set of tests of the robustness of the lensing-potential power spectrum, and construct a minimum-variance estimator likelihood over lensing multipoles 8 ≤  L  ≤ 400 (extending the range to lower L compared to 2015), which we use to constrain cosmological parameters. We find good consistency between lensing constraints and the results from the Planck CMB power spectra within the ΛCDM model. Combined with baryon density and other weak priors, the lensing analysis alone constrains σ 8 Ω m 0.25 = 0.589 ± 0.020 (1 σ errors). Also combining with baryon acoustic oscillation data, we find tight individual parameter constraints, σ 8  = 0.811 ± 0.019, H 0 = 67.9 −1.3 +1.2 km s −1 Mpc −1 , and Ω m = 0.303 −0.018 +0.016 . Combining with Planck CMB power spectrum data, we measure σ 8 to better than 1% precision, finding σ 8  = 0.811 ± 0.006. CMB lensing reconstruction data are complementary to galaxy lensing data at lower redshift, having a different degeneracy direction in σ 8  − Ω m space; we find consistency with the lensing results from the Dark Energy Survey, and give combined lensing-only parameter constraints that are tighter than joint results using galaxy clustering. Using the Planck cosmic infrared background (CIB) maps as an additional tracer of high-redshift matter, we make a combined Planck -only estimate of the lensing potential over 60% of the sky with considerably more small-scale signal. We additionally demonstrate delensing of the Planck power spectra using the joint and individual lensing potential estimates, detecting a maximum removal of 40% of the lensing-induced power in all spectra. The improvement in the sharpening of the acoustic peaks by including both CIB and the quadratic lensing reconstruction is detected at high significance.

• Aghanim, Nabila; Cheghasiahi, Yashar Akrami; Ashdown, M.; Aumont, J.; Baccigalupi, Carlo & Ballardini, M. [Vis alle 154 forfattere av denne artikkelen] (2020). Planck 2018 results: III. High Frequency Instrument data processing and frequency maps. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 641. doi: 10.1051/0004-6361/201832909. Fulltekst i vitenarkiv Vis sammendrag

  This paper presents the High Frequency Instrument (HFI) data processing procedures for the Planck 2018 release. Major improvements in mapmaking have been achieved since the previous Planck 2015 release, many of which were used and described already in an intermediate paper dedicated to the Planck polarized data at low multipoles. These improvements enabled the first significant measurement of the reionization optical depth parameter using Planck -HFI data. This paper presents an extensive analysis of systematic effects, including the use of end-to-end simulations to facilitate their removal and characterize the residuals. The polarized data, which presented a number of known problems in the 2015 Planck release, are very significantly improved, especially the leakage from intensity to polarization. Calibration, based on the cosmic microwave background (CMB) dipole, is now extremely accurate and in the frequency range 100–353 GHz reduces intensity-to-polarization leakage caused by calibration mismatch. The Solar dipole direction has been determined in the three lowest HFI frequency channels to within one arc minute, and its amplitude has an absolute uncertainty smaller than 0.35 μ K, an accuracy of order 10 −4 . This is a major legacy from the Planck HFI for future CMB experiments. The removal of bandpass leakage has been improved for the main high-frequency foregrounds by extracting the bandpass-mismatch coefficients for each detector as part of the mapmaking process; these values in turn improve the intensity maps. This is a major change in the philosophy of “frequency maps”, which are now computed from single detector data, all adjusted to the same average bandpass response for the main foregrounds. End-to-end simulations have been shown to reproduce very well the relative gain calibration of detectors, as well as drifts within a frequency induced by the residuals of the main systematic effect (analogue-to-digital convertor non-linearity residuals). Using these simulations, we have been able to measure and correct the small frequency calibration bias induced by this systematic effect at the 10 −4 level. There is no detectable sign of a residual calibration bias between the first and second acoustic peaks in the CMB channels, at the 10 −3 level.

• Hazumi, Masashi; Ade, Peter A.R.; Adler, A.; Allys, E.; Arnold, K & Auguste, D. [Vis alle 238 forfattere av denne artikkelen] (2020). LiteBIRD satellite: JAXA's new strategic L-class mission for all-sky surveys of cosmic microwave background polarization. Proceedings of SPIE, the International Society for Optical Engineering. ISSN 0277-786X. 11443. doi: 10.1117/12.2563050. Fulltekst i vitenarkiv Vis sammendrag

  LiteBIRD, the Lite (Light) satellite for the study of B-mode polarization and Inflation from cosmic background Radiation Detection, is a space mission for primordial cosmology and fundamental physics. JAXA selected LiteBIRD in May 2019 as a strategic large-class (L-class) mission, with its expected launch in the late 2020s using JAXA's H3 rocket. LiteBIRD plans to map the cosmic microwave background (CMB) polarization over the full sky with unprecedented precision. Its main scientific objective is to carry out a definitive search for the signal from cosmic inflation, either making a discovery or ruling out well-motivated inflationary models. The measurements of LiteBIRD will also provide us with an insight into the quantum nature of gravity and other new physics beyond the standard models of particle physics and cosmology. To this end, LiteBIRD will perform full-sky surveys for three years at the Sun-Earth Lagrangian point L2 for 15 frequency bands between 34 and 448 GHz with three telescopes, to achieve a total sensitivity of 2.16 μK-arcmin with a typical angular resolution of 0.5° at 100 GHz. We provide an overview of the LiteBIRD project, including scientific objectives, mission requirements, top-level system requirements, operation concept, and expected scientific outcomes.

• Aghanim, Nabila; Cheghasiahi, Yashar Akrami; Arroja, F.; Ashdown, M.; Aumont, J. & Baccigalupi, Carlo [Vis alle 194 forfattere av denne artikkelen] (2020). Planck 2018 results: I. Overview and the cosmological legacy of Planck. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 641. doi: 10.1051/0004-6361/201833880. Fulltekst i vitenarkiv Vis sammendrag

  The European Space Agency’s Planck satellite, which was dedicated to studying the early Universe and its subsequent evolution, was launched on 14 May 2009. It scanned the microwave and submillimetre sky continuously between 12 August 2009 and 23 October 2013, producing deep, high-resolution, all-sky maps in nine frequency bands from 30 to 857 GHz. This paper presents the cosmological legacy of Planck , which currently provides our strongest constraints on the parameters of the standard cosmological model and some of the tightest limits available on deviations from that model. The 6-parameter ΛCDM model continues to provide an excellent fit to the cosmic microwave background data at high and low redshift, describing the cosmological information in over a billion map pixels with just six parameters. With 18 peaks in the temperature and polarization angular power spectra constrained well, Planck measures five of the six parameters to better than 1% (simultaneously), with the best-determined parameter ( θ * ) now known to 0.03%. We describe the multi-component sky as seen by Planck , the success of the ΛCDM model, and the connection to lower-redshift probes of structure formation. We also give a comprehensive summary of the major changes introduced in this 2018 release. The Planck data, alone and in combination with other probes, provide stringent constraints on our models of the early Universe and the large-scale structure within which all astrophysical objects form and evolve. We discuss some lessons learned from the Planck mission, and highlight areas ripe for further experimental advances.

• Cheghasiahi, Yashar Akrami; Ashdown, M.; Aumont, J.; Baccigalupi, Carlo; Ballardini, M. & Banday, Anthony J. [Vis alle 119 forfattere av denne artikkelen] (2020). Planck intermediate results: LV. Reliability and thermal properties of high-frequency sources in the Second Planck Catalogue of Compact Sources. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 644. doi: 10.1051/0004-6361/201936794. Fulltekst i vitenarkiv Vis sammendrag

  We describe an extension of the most recent version of the Planck Catalogue of Compact Sources (PCCS2), produced using a new multi-band Bayesian Extraction and Estimation Package ( BeeP ). BeeP assumes that the compact sources present in PCCS2 at 857 GHz have a dust-like spectral energy distribution (SED), which leads to emission at both lower and higher frequencies, and adjusts the parameters of the source and its SED to fit the emission observed in Planck ’s three highest frequency channels at 353, 545, and 857 GHz, as well as the IRIS map at 3000 GHz. In order to reduce confusion regarding diffuse cirrus emission, BeeP ’s data model includes a description of the background emission surrounding each source, and it adjusts the confidence in the source parameter extraction based on the statistical properties of the spatial distribution of the background emission. BeeP produces the following three new sets of parameters for each source: (a) fits to a modified blackbody (MBB) thermal emission model of the source; (b) SED-independent source flux densities at each frequency considered; and (c) fits to an MBB model of the background in which the source is embedded. BeeP also calculates, for each source, a reliability parameter, which takes into account confusion due to the surrounding cirrus. This parameter can be used to extract sub-samples of high-frequency sources with statistically well-understood properties. We define a high-reliability subset ( BeeP/base ), containing 26 083 sources (54.1% of the total PCCS2 catalogue), the majority of which have no information on reliability in the PCCS2. We describe the characteristics of this specific high-quality subset of PCCS2 and its validation against other data sets, specifically for: the sub-sample of PCCS2 located in low-cirrus areas; the Planck Catalogue of Galactic Cold Clumps; the Herschel GAMA15-field catalogue; and the temperature- and spectral-index-reconstructed dust maps obtained with Planck ’s Generalized Needlet Internal Linear Combination method. The results of the BeeP extension of PCCS2, which are made publicly available via the Planck Legacy Archive, will enable the study of the thermal properties of well-defined samples of compact Galactic and extragalactic dusty sources.

• Montier, Ludovic; Mot, B; Bernardis, P. de; Maffei, B; Pisano, G & Columbro, F [Vis alle 236 forfattere av denne artikkelen] (2020). Overview of the medium and high frequency telescopes of the LiteBIRD space mission. Proceedings of SPIE, the International Society for Optical Engineering. ISSN 0277-786X. 11443. doi: 10.1117/12.2562243. Fulltekst i vitenarkiv Vis sammendrag

  LiteBIRD is a JAXA-led Strategic Large-Class mission designed to search for the existence of the primordial gravitational waves produced during the inflationary phase of the Universe, through the measurements of their imprint onto the polarization of the cosmic microwave background (CMB). These measurements, requiring unprecedented sensitivity, will be performed over the full sky, at large angular scales, and over 15 frequency bands from 34 GHz to 448 GHz. The LiteBIRD instruments consist of three telescopes, namely the Low-, Medium-and High-Frequency Telescope (respectively LFT, MFT and HFT). We present in this paper an overview of the design of the Medium-Frequency Telescope (89{224 GHz) and the High-Frequency Telescope (166{448 GHz), the so-called MHFT, under European responsibility, which are two cryogenic refractive telescopes cooled down to 5 K. They include a continuous rotating half-wave plate as the first optical element, two high-density polyethylene (HDPE) lenses and more than three thousand transition-edge sensor (TES) detectors cooled to 100 mK. We provide an overview of the concept design and the remaining specific challenges that we have to face in order to achieve the scientific goals of LiteBIRD.

• Sekimoto, Yutaro; Ade, Peter A.R.; Adler, A.; Allys, E.; Arnold, K & Auguste, D. [Vis alle 237 forfattere av denne artikkelen] (2020). Concept design of low frequency telescope for CMB B-mode polarization satellite LiteBIRD. Proceedings of SPIE, the International Society for Optical Engineering. ISSN 0277-786X. 11453. doi: 10.1117/12.2561841. Fulltekst i vitenarkiv Vis sammendrag

  LiteBIRD has been selected as JAXA’s strategic large mission in the 2020s, to observe the cosmic microwave background (CMB) B-mode polarization over the full sky at large angular scales. The challenges of LiteBIRD are the wide field-of-view (FoV) and broadband capabilities of millimeter-wave polarization measurements, which are derived from the system requirements. The possible paths of stray light increase with a wider FoV and the far sidelobe knowledge of -56 dB is a challenging optical requirement. A crossed-Dragone configuration was chosen for the low frequency telescope (LFT : 34–161 GHz), one of LiteBIRD’s onboard telescopes. It has a wide field-of-view (18° x 9°) with an aperture of 400 mm in diameter, corresponding to an angular resolution of about 30 arcminutes around 100 GHz. The focal ratio f/3.0 and the crossing angle of the optical axes of 90◦ are chosen after an extensive study of the stray light. The primary and secondary reflectors have rectangular shapes with serrations to reduce the diffraction pattern from the edges of the mirrors. The reflectors and structure are made of aluminum to proportionally contract from warm down to the operating temperature at 5 K. A 1/4 scaled model of the LFT has been developed to validate the wide field-of-view design and to demonstrate the reduced far sidelobes. A polarization modulation unit (PMU), realized with a half-wave plate (HWP) is placed in front of the aperture stop, the entrance pupil of this system. A large focal plane with approximately 1000 AlMn TES detectors and frequency multiplexing SQUID amplifiers is cooled to 100 mK. The lens and sinuous antennas have broadband capability. Performance specifications of the LFT and an outline of the proposed verification plan are presented.

• Thommesen, Harald; Andersen, Kristian Joten; Aurlien, Ragnhild; Banerji, Ranajoy; Brilenkov, Maksym & Fuskeland, Unni [Vis alle 11 forfattere av denne artikkelen] (2020). A Monte Carlo comparison between template-based and Wiener-filter CMB dipole estimators. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 643. doi: 10.1051/0004-6361/202038905. Fulltekst i vitenarkiv Vis sammendrag

  We review and compare two different cosmic microwave background (CMB) dipole estimators discussed in the literature and assess their performances through Monte Carlo simulations. The first method amounts to simple template regression with partial sky data, while the second method is an optimal Wiener filter (or Gibbs sampling) implementation. The main difference between the two methods is that the latter approach takes into account correlations with higher-order CMB temperature fluctuations that arise from nonorthogonal spherical harmonics on an incomplete sky, which for recent CMB data sets (such as Planck ) is the dominant source of uncertainty. For an accepted sky fraction of 81% and an angular CMB power spectrum corresponding to the best-fit Planck 2018 ΛCDM model, we find that the uncertainty on the recovered dipole amplitude is about six times smaller for the Wiener filter approach than for the template approach, corresponding to 0.5 and 3 μ K, respectively. Similar relative differences are found for the corresponding directional parameters and other sky fractions. We note that the Wiener filter algorithm is generally applicable to any dipole estimation problem on an incomplete sky, as long as a statistical and computationally tractable model is available for the unmasked higher-order fluctuations. The methodology described in this paper forms the numerical basis for the most recent determination of the CMB solar dipole from Planck , as summarized by Planck Collaboration Int. LVII (2020).

• Cheghasiahi, Yashar Akrami; Ashdown, M.; Aumont, J.; Baccigalupi, Carlo; Ballardini, M. & Banday, Anthony J. [Vis alle 154 forfattere av denne artikkelen] (2020). Planck 2018 results: IV. Diffuse component separation. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 641. doi: 10.1051/0004-6361/201833881. Fulltekst i vitenarkiv Vis sammendrag

  We present full-sky maps of the cosmic microwave background (CMB) and polarized synchrotron and thermal dust emission, derived from the third set of Planck frequency maps. These products have significantly lower contamination from instrumental systematic effects than previous versions. The methodologies used to derive these maps follow closely those described in earlier papers, adopting four methods ( Commander , NILC , SEVEM , and SMICA ) to extract the CMB component, as well as three methods ( Commander , GNILC , and SMICA ) to extract astrophysical components. Our revised CMB temperature maps agree with corresponding products in the Planck 2015 delivery, whereas the polarization maps exhibit significantly lower large-scale power, reflecting the improved data processing described in companion papers; however, the noise properties of the resulting data products are complicated, and the best available end-to-end simulations exhibit relative biases with respect to the data at the few percent level. Using these maps, we are for the first time able to fit the spectral index of thermal dust independently over 3° regions. We derive a conservative estimate of the mean spectral index of polarized thermal dust emission of β d  = 1.55  ±  0.05, where the uncertainty marginalizes both over all known systematic uncertainties and different estimation techniques. For polarized synchrotron emission, we find a mean spectral index of β s  = −3.1  ±  0.1, consistent with previously reported measurements. We note that the current data processing does not allow for construction of unbiased single-bolometer maps, and this limits our ability to extract CO emission and correlated components. The foreground results for intensity derived in this paper therefore do not supersede corresponding Planck 2015 products. For polarization the new results supersede the corresponding 2015 products in all respects.

• Cheghasiahi, Yashar Akrami; Ashdown, M.; Aumont, J.; Baccigalupi, Carlo; Ballardini, M. & Banday, Anthony J. [Vis alle 149 forfattere av denne artikkelen] (2020). Planck 2018 results: VII. Isotropy and statistics of the CMB. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 641. doi: 10.1051/0004-6361/201935201. Fulltekst i vitenarkiv Vis sammendrag

  Analysis of the Planck 2018 data set indicates that the statistical properties of the cosmic microwave background (CMB) temperature anisotropies are in excellent agreement with previous studies using the 2013 and 2015 data releases. In particular, they are consistent with the Gaussian predictions of the ΛCDM cosmological model, yet also confirm the presence of several so-called “anomalies” on large angular scales. The novelty of the current study, however, lies in being a first attempt at a comprehensive analysis of the statistics of the polarization signal over all angular scales, using either maps of the Stokes parameters, Q and U , or the E -mode signal derived from these using a new methodology (which we describe in an appendix). Although remarkable progress has been made in reducing the systematic effects that contaminated the 2015 polarization maps on large angular scales, it is still the case that residual systematics (and our ability to simulate them) can limit some tests of non-Gaussianity and isotropy. However, a detailed set of null tests applied to the maps indicates that these issues do not dominate the analysis on intermediate and large angular scales (i.e., ℓ  ≲ 400). In this regime, no unambiguous detections of cosmological non-Gaussianity, or of anomalies corresponding to those seen in temperature, are claimed. Notably, the stacking of CMB polarization signals centred on the positions of temperature hot and cold spots exhibits excellent agreement with the ΛCDM cosmological model, and also gives a clear indication of how Planck provides state-of-the-art measurements of CMB temperature and polarization on degree scales.

• Cheghasiahi, Yashar Akrami; Arroja, F.; Ashdown, M.; Aumont, J.; Baccigalupi, Carlo & Ballardini, M. [Vis alle 160 forfattere av denne artikkelen] (2020). Planck 2018 results: IX. Constraints on primordial non-Gaussianity. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 641. doi: 10.1051/0004-6361/201935891. Fulltekst i vitenarkiv Vis sammendrag

  We analyse the Planck full-mission cosmic microwave background (CMB) temperature and E -mode polarization maps to obtain constraints on primordial non-Gaussianity (NG). We compare estimates obtained from separable template-fitting, binned, and optimal modal bispectrum estimators, finding consistent values for the local, equilateral, and orthogonal bispectrum amplitudes. Our combined temperature and polarization analysis produces the following final results: f NL local = −0.9 ± 5.1; f NL equil = −26 ± 47; and f NL ortho = −38 ± 24 (68% CL, statistical). These results include low-multipole (4 ≤  ℓ  &lt;  40) polarization data that are not included in our previous analysis. The results also pass an extensive battery of tests (with additional tests regarding foreground residuals compared to 2015), and they are stable with respect to our 2015 measurements (with small fluctuations, at the level of a fraction of a standard deviation, which is consistent with changes in data processing). Polarization-only bispectra display a significant improvement in robustness; they can now be used independently to set primordial NG constraints with a sensitivity comparable to WMAP temperature-based results and they give excellent agreement. In addition to the analysis of the standard local, equilateral, and orthogonal bispectrum shapes, we consider a large number of additional cases, such as scale-dependent feature and resonance bispectra, isocurvature primordial NG, and parity-breaking models, where we also place tight constraints but do not detect any signal. The non-primordial lensing bispectrum is, however, detected with an improved significance compared to 2015, excluding the null hypothesis at 3.5 σ . Beyond estimates of individual shape amplitudes, we also present model-independent reconstructions and analyses of the Planck CMB bispectrum. Our final constraint on the local primordial trispectrum shape is g NL local = (−5.8 ± 6.5) × 10 4 (68% CL, statistical), while constraints for other trispectrum shapes are also determined. Exploiting the tight limits on various bispectrum and trispectrum shapes, we constrain the parameter space of different early-Universe scenarios that generate primordial NG, including general single-field models of inflation, multi-field models (e.g. curvaton models), models of inflation with axion fields producing parity-violation bispectra in the tensor sector, and inflationary models involving vector-like fields with directionally-dependent bispectra. Our results provide a high-precision test for structure-formation scenarios, showing complete agreement with the basic picture of the ΛCDM cosmology regarding the statistics of the initial conditions, with cosmic structures arising from adiabatic, passive, Gaussian, and primordial seed perturbations.

• Cheghasiahi, Yashar Akrami; Arroja, F.; Ashdown, M.; Aumont, J.; Baccigalupi, Carlo & Ballardini, M. [Vis alle 175 forfattere av denne artikkelen] (2020). Planck 2018 results: X. Constraints on inflation. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 641. doi: 10.1051/0004-6361/201833887. Fulltekst i vitenarkiv Vis sammendrag

  We report on the implications for cosmic inflation of the 2018 release of the Planck cosmic microwave background (CMB) anisotropy measurements. The results are fully consistent with those reported using the data from the two previous Planck cosmological releases, but have smaller uncertainties thanks to improvements in the characterization of polarization at low and high multipoles. Planck temperature, polarization, and lensing data determine the spectral index of scalar perturbations to be n s  = 0.9649 ± 0.0042 at 68% CL. We find no evidence for a scale dependence of n s , either as a running or as a running of the running. The Universe is found to be consistent with spatial flatness with a precision of 0.4% at 95% CL by combining Planck with a compilation of baryon acoustic oscillation data. The Planck 95% CL upper limit on the tensor-to-scalar ratio, r 0.002  &lt;  0.10, is further tightened by combining with the BICEP2/Keck Array BK15 data to obtain r 0.002  &lt;  0.056. In the framework of standard single-field inflationary models with Einstein gravity, these results imply that: (a) the predictions of slow-roll models with a concave potential, V ″( ϕ ) &lt; 0, are increasingly favoured by the data; and (b) based on two different methods for reconstructing the inflaton potential, we find no evidence for dynamics beyond slow roll. Three different methods for the non-parametric reconstruction of the primordial power spectrum consistently confirm a pure power law in the range of comoving scales 0.005 Mpc −1  ≲  k  ≲ 0.2 Mpc −1 . A complementary analysis also finds no evidence for theoretically motivated parameterized features in the Planck power spectra. For the case of oscillatory features that are logarithmic or linear in k , this result is further strengthened by a new combined analysis including the Planck bispectrum data. The new Planck polarization data provide a stringent test of the adiabaticity of the initial conditions for the cosmological fluctuations. In correlated, mixed adiabatic and isocurvature models, the non-adiabatic contribution to the observed CMB temperature variance is constrained to 1.3%, 1.7%, and 1.7% at 95% CL for cold dark matter, neutrino density, and neutrino velocity, respectively. Planck power spectra plus lensing set constraints on the amplitude of compensated cold dark matter-baryon isocurvature perturbations that are consistent with current complementary measurements. The polarization data also provide improved constraints on inflationary models that predict a small statistically anisotropic quadupolar modulation of the primordial fluctuations. However, the polarization data do not support physical models for a scale-dependent dipolar modulation. All these findings support the key predictions of the standard single-field inflationary models, which will be further tested by future cosmological observations.

Se alle arbeider i NVA

• Aghanim, N.; Akrami, Y.; Ashdown, M.; Aumont, J.; Baccigalupi, C. & Ballardini, M. [Vis alle 181 forfattere av denne artikkelen] (2021). Erratum: Planck 2018 results: VI. Cosmological parameters (Astronomy and Astrophysics (2020) 641 (A6) DOI: 10.1051/0004-6361/201833910). Astronomy and Astrophysics (A & A). ISSN 0004-6361. 652. doi: 10.1051/0004-6361/201833910e. Fulltekst i vitenarkiv
• Stutzer, Nils-Ole; Eriksen, Hans Kristian Kamfjord & Wehus, Ingunn Kathrine (2025). Towards the first line intensity map of cosmic carbon monoxide with the COMAP Experiment. Universitetet i Oslo. Fulltekst i vitenarkiv Vis sammendrag

  From Darkenss to Light – Towards mapping the Faint Star-Forming Universe Modern cosmology has uncovered many details of the evolution and content of the Universe by studying the cosmic microwave background (CMB) at early times and the large-scale galaxy distribution of the late Universe. However, eras in between, like the Epochs of Reionization (EoR) and Galaxy Assembly (EoGA), remain data-starved. Line intensity mapping (LIM) aims to fill this gap by mapping the large-scale aggregate line emission of all bright and diffuse cosmic sources in 3D. In this thesis, I contribute to this effort by developing a data analysis pipeline for the CO Mapping Array Project (COMAP) LIM experiment. COMAP aims to map the large-scale distribution of star-forming carbon monoxide gas emitted around the EoR and EoGA. I present a robust method for cleaning and calibrating the data, ultimately generating 3D sky maps of CO emission. My analysis assesses the statistical properties of the maps to extract insight into the physics of the star-forming Universe. This work yields the strongest constraints on the large-scale cosmic carbon monoxide reported in the literature, and COMAP is enroute towards a world’s first detection. Lastly, I propose future improvements to the COMAP pipeline based on the Bayesian sampling techniques originally developed for CMB surveys.

• Basyrov, Artem; Eriksen, Hans Kristian Kamfjord; Wehus, Ingunn Kathrine & Gjerløw, Eirik (2024). Bayesian approach to CMB data analysis: from component separation to optimal mapmaking. Universitetet i Oslo. Fulltekst i vitenarkiv Vis sammendrag

  This work is done in the context of a particular field in cosmology, which studies the earliest observable light in the Universe, called the cosmic microwave background (CMB). The analysis of data from different CMB experiments is a difficult task in itself, comprising many steps and requiring a very high level of accuracy. In this thesis we have developed new statistical methods to apply in various parts of the CMB data analysis. We are using methods from Bayesian statistics, that is, statistical methods where the model we have chosen is driven by the observational data itself. This allows for a more accurate estimation of both instrumental effects particular to a given experiment and astrophysical effects, such as cosmic dust emission and CMB itself. In this work we are also showing the power of the joint analysis of different experiments, where it becomes easier to distinguish and estimate what part of the data can be attributed to the astrophysical phenomena and what to the instrumental systematics. These methods can be applied to future CMB experiments, enhancing our analysis not only by enhancing the quality of instruments, but also by building upon all the preexisting knowledge in the field.

• San, Metin; Wehus, Ingunn Kathrine; Eriksen, Hans Kristian Kamfjord; Watts, Duncan; Doré, Olivier & Elgarøy, Øystein (2024). Modelling the infrared sky through global end-to-end analysis. Faculty of Mathematics and Natural Sciences. Fulltekst i vitenarkiv
• Herman, Daniel Christopher; Wehus, Ingunn Kathrine & Eriksen, Hans Kristian Kamfjord (2023). Cosmoglobe: Deconstructing the microwave and sub-mm sky. Universitetet i Oslo. Fulltekst i vitenarkiv Vis sammendrag

  The cosmic microwave background is one of the most prominent sources of cosmological information. Modern cosmological theories rely upon both small- and large-scale observations of the CMB. As a necessity, these observations rely heavily upon the ability to properly model the instrument making the observations as well as emission from the Galaxy. This thesis sets out to describe a broad series of topics with respect to CMB observations, underlining the interplay between the constituent parts. The goal of CMB observations today is to set better constraints on cosmological theories, particularly aiming for a detection or exclusion of direct evidence for inflation. It is vital to introduce several topics in this thesis in order to talk about the details of microwave and sub-mm data analysis. The first part of the manuscript introduces modern cosmology which is the framework for our current understanding of the universe at large physical and temporal scales. This is followed by a primer on the microwave sky, which is full of several non-cosmological signals, commonly referred to in the field as foregrounds. Additionally, several historical, contemporary, and future observatories are introduced, with a few common telescope systematics introduced in the following chapters. Finally, a detailed introduction to the methodologies utilized in this thesis is given. The work outlined here emphasizes the tight coupling between each of these components and highlights the benefits of including the modeling of these within a unified framework. This is directly demonstrated within the papers presented here. Modeling the instrument and Galactic signals together at the time ordered level has made the 44 GHz LFI data, which was previously discarded because of the high level of unmodeled systematics, once again usable for cosmological analysis by the BeyondPlanck project. The Cosmoglobe Data Release 1 (DR1) has similarly recovered the WMAP W-band polarization data for cosmological analysis for the first time, which was made possible due to the common calibration allowed by jointly analyzing LFI and WMAP data. The Commander framework used for the above analyses provided a suite of frequency maps, each of which represent a different realization of what the sky and instrument look like. The frequency maps produced by the BeyondPlanck project were used to set upper bounds for the maximum polarization fraction for large-scale anomalous microwave emission to be under 3.5 %, marginalizing over LFI systematics. Modeling of instrumental systematics is an integral part of CMB data analysis, with a select few instrumental systematics discussed in the latter parts of the manuscript. Nonlinearities in the LFI analog-to-digital converters inspired a new set of corrections to be created. These corrections, which are by nature degenerate with the calibration of the instrument, show that neglecting this systematic effect may obfuscate a weak cosmological signal. Systematic effects such as calibration estimates and instrument bandpasses couple directly to estimates of the microwave sky. This complicates determination of what the sky truly looks like as well as what data the instrument is actually taking. The tight coupling between instrumental and sky estimates has inspired the use of calibration priors for the WMAP K-band in Cosmoglobe DR1. Additionally, knowledge about the interstellar medium has spurred the implementation of informative priors from data outside the microwave/sub-mm regime, such as the application of neutral hydrogen data as a prior for the anomalous microwave emission component within the BeyondPlanck project. The above examples illustrate the importance of bringing not only as much data together as possible, but to also compile broad types of experience to get the best view of the CMB as possible. The research presented here has primarily focused on component separation, coming in the form of the development of an independent pixel-based component separation software, dang, in addition to contributing to and utilizing the Commander software. In an attempt to practice pedagogy, the introduction to Bayesian component separation methods is in depth and explicit, hopefully serving as a starting point for future researchers who wish to implement similar frameworks for their own work.

• Brilenkov, Maksym; Wehus, Ingunn Kathrine & Eriksen, Hans Kristian Kamfjord (2023). From theory to practice: Reproducibility and Open Science in the CMB field. Universitetet i Oslo. Fulltekst i vitenarkiv Vis sammendrag

  The study of the cosmic microwave background (CMB) radiation is a pillar of modern cosmology that enables us to understand the history, the evolution of structures, and the global shape (topology) of the Universe. This thesis addresses various theoretical, numerical, and observational aspects of this field. On the theoretical side, I extended the current cosmological LCDM standard model by accounting for the effect of high-energetic neutrinos, and I have derived analytical expressions for the gravitational potential in a trigonometric representation for two distinct non-trivial topologies of the Universe. On the numerical side, I have, as a member of the BeyondPlanck collaboration, developed a common computational infrastructure that allows easy installation and deployment of the world's leading code for end-to-end Bayesian CMB analysis called Commander3. We have used this code to reprocess the Planck LFI observations, and our new products represent today the world's cleanest maps of the microwave sky between 30 and 70 GHz. While this code was originally designed to perform massive Monte Carlo sampling, I have modified it to also be able to produce traditional frequentist-style simulations, which is useful for code validation and error propagation purposes for a broad range of current and future CMB experiments.

• Aurvik, Ragnhild; Eriksen, Hans Kristian Kamfjord & Wehus, Ingunn Kathrine (2023). The search for inflationary B-mode signal with future CMB experiments. Universitetet i Oslo. Fulltekst i vitenarkiv Vis sammendrag

  The oldest radiation in the universe is the Cosmic Microwave Background (CMB) radiation. Analysing the CMB is like analysing a baby picture of the Universe, and gives us unique information on what the Universe looked like at a very early stage. There are however some missing pieces in our understanding of how the Universe was created. One of them is the prediction that the Universe expanded faster than the speed of light for an extremely short period of time right after our Universe was born, in the period of cosmic inflation. This should have created gravitational waves. Detecting the gravitational wave signal has however proven very difficult, and we do not know how strong it is. I have been working with future space telescopes, designed to detect these inflationary gravitational waves. To make sure they are sensitive enough, we make simulations of how they will observe the sky, including the noise from the telescope. Then we try to find the signals we put into the simulations. By doing so we can test if the telescope perform as expected. We also get to test our data analysis algorithms, and can explore and suggest potential improvements for the telescope.

• Eskilt, Johannes Røsok; Wehus, Ingunn Kathrine; Eriksen, Hans Kristian Kamfjord; Watts, Duncan; Komatsu, Eiichiro & Hansen, Frode Kristian (2023). Signatures of New Physics in the CMB: From Cosmic Topology to Cosmic Birefringence. Universitetet i Oslo. Fulltekst i vitenarkiv Vis sammendrag

  The cosmic microwave background (CMB) is not just the oldest light in the Universe but also the oldest polarized light. By measuring its patterns, we can learn large amounts of information about the origin of the Universe and its content. This work focuses on some of the allowed ''shapes'', or more precisely, topologies of the Universe. We describe their potential patterns in the CMB, showing that the shape of the Universe is likely impossible to be measured in the CMB if its size is too large. We also provide evidence for cosmic birefringence, a potentially new phenomenon that might have rotated the linear polarization of the CMB photons. This work provides evidence for the signal being independent of the energy of the photons, which is consistent with a new fundamental particle called axions. In addition, we show that the signal is unlikely to be attributed to systematic effects or astrophysical foregrounds, and that the rotation must have started after the epoch when the CMB was created. If proven to be real, it would be revolutionary for cosmology and particle physics, and it could shed light on what either dark matter or dark energy is.

• Andersen, Kristian Joten; Eriksen, Hans Kristian Kamfjord & Wehus, Ingunn Kathrine (2022). Improved Planck processing through integrated component separation. Universitetet i Oslo. Fulltekst i vitenarkiv Vis sammendrag

  In this thesis we take a look at the importance of component separation in the processing of data from the Planck satellite mission. We show how integrating component separation in the form of a sky model improves the instrumental calibration in the processing of the raw data, reducing systematic instrumental effects and producing cleaner sky maps. The thesis gives an overview to the Planck data analyses of the NPIPE and the BeyondPlanck teams; the former being the first joint processing of all the Planck data in one framework; the latter being the first end-to-end Bayesian analysis framework, sampling the full posterior distribution of the model parameters allowing for full uncertainty propagation through the entire pipeline. With the frameworks of NPIPE and BeyondPlanck, we are laying the groundwork for the Cosmic Microwave Background (CMB) community to face its greatest challenge of today; the detection of divergence-free polarization in the CMB from primordial gravitational waves, giving direct evidence for cosmic inflation.

• Svalheim, Trygve Leithe; Wehus, Ingunn Kathrine & Eriksen, Hans Kristian Kamfjord (2022). Closing the Loop: Joint Analysis of CMB Systematics and Foregrounds. Universitetet i Oslo. Fulltekst i vitenarkiv Vis sammendrag

  The Cosmic Microwave Background (CMB) radiation is the oldest signal in the universe. It teaches us about the first moments after the universe came into existence, and thus informs us about its subsequent evolution. The CMB serves as the faint backdrop of the night sky, obscured by all the other astrophysical objects (primarily clouds of gas), which we call foregrounds. For precise measurements of the CMB, we require detailed characterization of these, and also of the observing instruments' systematics. Furthermore, the problems of foreground separation and instrument systematics are tightly interwoven. This thesis presents my work on disentangling this relationship. This is done by leveraging observations from several different experiments and simultaneous consideration of systematics and foregrounds in a “loop”-like manner. Through the application of these methods, my colleagues and I have created some of the cleanest maps of the sky in the microwave range, in the world. These maps in turn inform us about important properties of the universe.

• Ihle, Håvard Tveit; Wehus, Ingunn Kathrine & Eriksen, Hans Kristian Kamfjord (2021). Bayesian Data Analysis for Intensity Mapping and CMB Experiments. Universitetet i Oslo. Fulltekst i vitenarkiv Vis sammendrag

  In the developing field of line intensity mapping (LIM), an approach to measuring the aggregate emission from various spectral lines in the early universe, as well as when searching for primordial B-modes in the Cosmic Microwave Background, we are looking for a weak signal where we not only need to integrate down large amounts of noise, but also have to control and remove instrumental systematics and foreground emission to a very high precision. This is the main challenge this thesis is grappling with. I outline the data analysis pipeline for COMAP, a LIM experiment targeting line emission from carbon monoxide in star forming regions in the early universe. We discuss everything from filtering and calibration of the raw data, to robust power spectrum estimation and astrophysical inference. Our preliminary results show that the measured power spectrum is consistent with white noise, which means that we are successfully suppressing all systematics to below white noise levels. I also discuss the BeyondPlanck project, an ambitious project to develop an end-to-end Bayesian data analysis pipeline for CMB experiments, where I worked on noise estimation, systematics and calibration.

• Foss, Marie Kristine; Wehus, Ingunn Kathrine & Eriksen, Hans Kristian Kamfjord (2021). Mapping the Teenage Universe with COMAP. Faculty of Mathematics and Natural Sciences. Fulltekst i vitenarkiv

Se alle arbeider i NVA