Raelyn Sullivan

• Banday, A. J.; Gimeno-Amo, C.; Diego-Palazuelos, P.; Hoz, E. de la; Gruppuso, A. & Raffuzzi, N. [Show all 104 contributors for this article] (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. Full text in Research Archive Show summary

  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.

• Sullivan, Raelyn; Abghari, Arefe; Diego-Palazuelos, Patricia; Hergt, Lukas T. & Scott, Douglas (2025). Planck PR4 (NPIPE) map-space cosmic birefringence. Journal of Cosmology and Astroparticle Physics (JCAP). 2025(06). doi: 10.1088/1475-7516/2025/06/025. Full text in Research Archive Show summary

  Cosmic birefringence is an effect where the plane of polarisation of the cosmic microwave background (CMB) is rotated by an angle β through coupling to a hypothetical parity-violating field. We analyse the Planck Public Release 4 (PR4 or NPIPE) data using a map-space analysis method and find β= 0.46° ± 0.04°(stat.) ± 0.28°(syst.) for SEVEM CMB maps and β = 0.48° ± 0.04°(stat.) ± 0.28°(syst.) for Commander CMB maps. These values are slightly higher than previously published results, which may be explained by the fact that we have not attempted to remove any potential bias from miscalibration of the Planck polarimeters. The uncertainty in this miscalibration dominates the systematic uncertainty, which also means that our results are consistent with no parity violation. An advantage of the map-space analysis is that it is easy to investigate any variations on the sky, for example caused by foreground contamination. Our results for isotropic birefringence are fairly robust against different spatial data cuts, but there may be hints of a foreground systematic (north versus south hemispheres) or uncontrolled miscalibration effect (T peaks versus E peaks) that should be followed up in future studies. We additionally find no evidence of a cosmic birefringence dipole (anisotropic birefringence).

• Ruiz-Granda, M.; Diego-Palazuelos, P.; Gimeno-Amo, C.; Vielva, P.; Lonappan, A.I. & Namikawa, T. [Show all 105 contributors for this article] (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. Full text in Research Archive Show summary

  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. [Show all 110 contributors for this article] (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. Full text in Research Archive Show summary

  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. [Show all 110 contributors for this article] (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. Full text in Research Archive Show summary

  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. [Show all 114 contributors for this article] (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. Full text in Research Archive Show summary

  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).

• Giardiello, S.; Carones, A.; Ghigna, T.; Pagano, L.; Piacentini, F. & Montier, L. [Show all 98 contributors for this article] (2025). Requirements on bandpass resolution and measurement precision for LiteBIRD. Journal of Cosmology and Astroparticle Physics (JCAP). 2025(10). doi: 10.1088/1475-7516/2025/10/038. Full text in Research Archive Show summary

  Systematic effects can hinder the sought-after detection of primordial gravitational waves, impacting the reconstruction of the B -mode polarization signal which they generate in the cosmic microwave background (CMB). In this work, we study the impact of an imperfect knowledge of the instrument bandpasses on the estimate of the tensor-to-scalar ratio r in the context of the next-generation LiteBIRD satellite. We develop a pipeline to integrate over the bandpass transmission in both the time-ordered data (TOD) and the map-making processing steps. We introduce the systematic effect by having a mismatch between the “real”, high resolution bandpass τ , entering the TOD, and the estimated one τ s , used in the map-making. We focus on two aspects: the effect of degrading the τ s resolution, and the addition of a Gaussian error σ to τ s . To reduce the computational load of the analysis, the two effects are explored separately, for three representative LiteBIRD channels (40 GHz, 140 GHz and 402 GHz) and for three bandpass shapes. Computing the amount of bias on r , Δ r , caused by these effects on a single channel, we find that a resolution ≲ 1.5 GHz and σ ≲ 0.0089 do not exceed the LiteBIRD budget allocation per systematic effect, Δ r < 6.5 × 10 -6 . We then check that propagating separately the uncertainties due to a resolution of 1 GHz and a measurement error with σ = 0.0089 in all LiteBIRD frequency channels, for the most pessimistic bandpass shape of the three considered, still produces a Δ r < 6.5 × 10 -6 . This is done both with the simple deprojection approach and with a blind component separation technique, the Needlet Internal Linear Combination (NILC). Due to the effectiveness of NILC in cleaning the systematic residuals, we have tested that the requirement on σ can be relaxed to σ ≲ 0.05.

• Carralot, F.; Carones, A.; Krachmalnicoff, N.; Ghigna, T.; Novelli, A. & Pagano, L. [Show all 109 contributors for this article] (2025). Requirements on the gain calibration for LiteBIRD polarisation data with blind component separation. Journal of Cosmology and Astroparticle Physics (JCAP). 2025(1). doi: 10.1088/1475-7516/2025/01/019. Full text in Research Archive Show summary

  The detection of primordial B modes of the cosmic microwave background (CMB) could provide information about the early stages of the Universe's evolution. The faintness of this signal requires exquisite calibration accuracy and control of instrumental systematic effects which otherwise could bias the measurements. In this work, we study the impact of an imperfect relative polarisation gain calibration on the recovered value of the tensor-to-scalar ratio r for the LiteBIRD experiment, through the application of the blind Needlet Internal Linear Combination (NILC) foreground-cleaning method. We derive requirements on the relative calibration accuracy of the overall polarisation gain (Δgν) for each LiteBIRD frequency channel. Our results show that minimum variance techniques, as NILC, are less sensitive to systematic gain calibration uncertainties compared to a parametric approach, if the latter is not equipped with a proper modelling of these instrumental effects. In this study, the most stringent requirements are found in the channels where the CMB signal is relatively brighter, with the tightest constraints at 166 GHz (Δgν ≈ 0.16%). This differs from the outcome of an analogous analysis performed with a parametric method, where the tightest requirements are obtained for the foreground-dominated channels. Gain calibration uncertainties, corresponding to the derived requirements, are then simultaneously propagated into all frequency channels. By doing so, we find that the overall impact on estimated r is lower than the total gain systematic budget for LiteBIRD approximately by a factor 5, due to the correlations of the impacts of gain calibration uncertainties in different frequency channels. In order to decouple the systematic effect from the specific choice of the model, we derive the requirements assuming constant spectral parameters for the foreground emission. To assess the robustness of the obtained results against more realistic scenarios, we repeat the analysis assuming sky models of intermediate and high complexity. In these further cases, we adopt an optimised NILC pipeline, called the Multi-Clustering NILC (MC-NILC). We find that the impact of gain calibration uncertainties on r is lower than the LiteBIRD gain systematics budget for the intermediate-complexity sky model. For the high-complexity case, instead, it would be necessary to tighten the requirements by a factor 1.8.

• Hoz, E. de la; Diego-Palazuelos, P.; Errard, J.; Gruppuso, A.; Jost, B. & Sullivan, Raelyn [Show all 115 contributors for this article] (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. Full text in Research Archive Show summary

  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°.

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