Rubinur Khatun

• Scialpi, M.; Mannucci, F.; D’Amato, Q.; Marconcini, C.; Cresci, G. & Marconi, A. [Vis alle 37 forfattere av denne artikkelen] (2026). Cosmic Duets: I. High-spatial resolution spectroscopy of dual and lensed active galactic nuclei with MUSE-NFM. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 709. doi: 10.1051/0004-6361/202558548. Fulltekst i vitenarkiv Vis sammendrag

  We present the first-year results of the MUSE Large Program “Cosmic Duets”, whose goal is to obtain adaptive-optics assisted MUSE observations with a typical angular resolution of 0.1″ − 0.2″ in order to provide integral-field spectroscopy of sub-arcsec separation dual and lensed active galactic nucleus (AGN) candidates. These observations reveal previously unexplored properties of dual and lensed systems that are key to understanding galaxy evolution, supermassive black hole mergers, and strong-lensing modeling. Targets were efficiently selected using the Gaia multipeak (GMP) technique, which identifies pairs of point-like sources with angular separations below 0.8″ in the Gaia catalog. MUSE spatially resolved spectroscopy provides accurate redshifts, ionization diagnostics, and identification of absorption systems along the line of sight. We report results for 30 GMP-selected targets at z = 0.5 − 3.5. All systems show at least two spatially resolved components. Nineteen objects are confirmed as AGN multiplets, including six dual AGN, ten doubly lensed quasars, and three quadruply lensed systems, while the remaining 11 correspond to chance alignments with foreground stars. Among all the spectroscopically confirmed dual AGN in the literature, 27 pairs have projected separations below 7 kpc in this redshift regime, and our sample accounts for 22% of the total. We studied dual and lensed AGN distributions as a function of redshift, magnitude, and projected separation while accounting for selection effects, and we find that bright systems (J ≲ 16.5) are dominated by lensed quasars, whereas the relative fraction of dual AGN increases at fainter magnitudes. This first-year sample demonstrates the high efficiency of GMP preselection combined with MUSE spectroscopy for identifying sub-arcsec dual and lensed AGN. The full program, targeting ∼150 systems, will enable statistical studies of dual AGN incidence as a function of redshift, separation, and luminosity and allow for precise characterization of the mass composition and distribution in strong lensing galaxies.

• Magliocchetti, M.; Marca, A. La; Bisigello, L.; Bondi, M.; Ricci, F. & Fotopoulou, S. [Vis alle 168 forfattere av denne artikkelen] (2026). Euclid: Quick Data Release (Q1) – The connection between galaxy close encounters and radio activity. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 711. doi: 10.1051/0004-6361/202557391. Fulltekst i vitenarkiv Vis sammendrag

  Using the vast statistics provided by both Euclid and the LOFAR surveys, we present the first large-scale study of the connection among radio emission, its morphology, and the merging properties of the hosts of radio sources up to z ∼ 2. By dividing the radio sample into active galactic nuclei (AGNs) and star-forming galaxies, we find that radio-emitting AGNs show a clear preference for residing within galaxies undergoing a merging event. This is more significant for AGNs that present complex or extended radio emission; indeed, about half of them are associated with merging systems, while only ∼15% are hosted by a non-interacting galaxy. The observed trend is primarily driven by AGNs residing at z < 1, especially in the case of high – P_144 MHz > 10^24 W Hz−1 sr−1 – radio luminosities (∼56% in mergers versus ∼10% in non-mergers regardless of radio appearance). On the other hand, this preference seems to disappear at higher redshifts, where only bright AGNs with extended radio emission still prefer galaxies undergoing a merging event. The situation is reversed in the case of radio-emitting star-forming galaxies, which are preferentially associated with non-interacting systems. This is more significant as we move towards low-radio-luminosity/star-formation objects (P_144 MHz < 10^23 W Hz−1 sr−1) for which we find ∼40% in non-mergers versus ∼20% in mergers. These values hold regardless of redshift. We interpreted the above result for AGNs with their need to accrete outer gas from local encounters in order to trigger (radio) activity, especially in the case of extended radio emission such as hot spots and lobes. This is mostly observed at z < 1, since galaxies in the local Universe are more gas deprived than their higher redshift counterparts. Internal gas reservoirs instead seem sufficient to trigger star formation within the majority of galaxies, which indeed mostly appear as non-interacting systems at all redshifts probed.

• Fida, Ayisha; Nandi, Sumana; Das, Mousumi; Khatun, Rubinur; Shanbhog, S. & Kharb, Preeti [Vis alle 7 forfattere av denne artikkelen] (2026). Finding the evolutionary link between ULIRGs and radio galaxies. Monthly notices of the Royal Astronomical Society. ISSN 0035-8711. 549(4). doi: 10.1093/mnras/stag948. Fulltekst i vitenarkiv Vis sammendrag

  Ultraluminous infrared galaxies (ULIRGs) are the remnants of the major mergers of gas-rich galaxies. They are dusty systems and are extremely luminous in the infrared. Both starbursts and active galactic nucleus (AGN) activity supply power in these systems, but it is not clear how these two activities are related to the overall evolution of the merger remnant. Studies suggest that there may be an evolutionary link between ULIRGs and radio galaxies. Radio observations of ULIRGs are a useful tool for understanding this evolutionary path as well as studying the energy contributions from starbursts and AGN. We perform a systematic census of these signatures in 38 ULIRGs using upgraded Giant Metrewave Radio Telescope observations and archival radio data. In the sample, 30 sources have enough frequency coverage to obtain their radio spectrum. Of these, 17 sources show a turnover frequency between 63 and 509 MHz and a spectral age variation from 0.009 to 44 Myr. Also, eight sources have extended structures with projected linear sizes varying from 0.7 to 11 kpc. Our results indicate that the primary energy source in these systems is the AGN rather than star formation. The majority of the ULIRGs in our sample, particularly those in the post-merger stage, exhibit gigahertz-peaked spectrum or compact steep spectrum-like characteristics, suggesting that they are evolving into young radio galaxies. We note that six sources with high star formation activity show a low-frequency turnover and a smaller spectral age; we confirm these six sources host buried AGN. This study enables us to trace the evolutionary link between ULIRGs and radio galaxies.

• D’Amato, Quirino; Mannucci, Filippo; Sonnenfeld, Alessandro; Scialpi, Martina; Nightingale, James W. & Spingola, Cristiana [Vis alle 43 forfattere av denne artikkelen] (2026). Milky-Way-like stars in a galaxy core 8 billion years ago revealed by gravitational lensing. Nature Astronomy. 10(6), s. 901–912. doi: 10.1038/s41550-026-02819-4. Fulltekst i vitenarkiv Vis sammendrag

  The assembly of stellar-dominated cores in elliptical galaxies is key to understanding how cosmic structures evolved. Gravitational lensing offers unique insights into the nature of their stars. Here we report the discovery of an extremely compact quadruply lensed quasar (radius ~0.2″), whose lensing galaxy at a redshift of 1.055 (5.5 billion years after the Big Bang) features a lensing mass of only ~2 × 10^10 M⊙. Bayesian analysis, based on the exceptional properties of the system and standard scaling relations, makes it possible to sample the central galactic initial mass function with great accuracy and in a previously uncharted regime in terms of mass and redshift. We find it to be consistent with the initial mass function of the Milky Way while excluding bottom-heavy functions. This indicates that the core either grew slowly or underwent early disruptive events altering its stellar build-up, potentially challenging the classical view in which bulges form rapidly and remain unchanged by later interactions.

• Ali, Arshi; Sebastian, Biny; Kakkad, Darshan; Silpa, Sasikumar; Kharb, Preeti & O’Dea, Christopher P. [Vis alle 12 forfattere av denne artikkelen] (2025). Jet-mode Feedback in NGC 5972: Insights from Resolved MUSE, GMRT, and VLA Observations. The Astrophysical Journal (ApJ). ISSN 0004-637X. 984(2). doi: 10.3847/1538-4357/adc38d. Fulltekst i vitenarkiv Vis sammendrag

  NGC 5972, a Voorwerp galaxy, features a helical-shaped extended emission-line region (EELR) with a radius >10 kpc and an S-shaped radio structure spanning about 470 kpc. We use the Very Large Telescope, Multi Unit Spectroscopic Explorer, Giant Metrewave Radio Telescope, and Very Large Array (VLA) to study the stellar and ionized gas kinematics and how the radio jet influences the gas in the galaxy. Our sensitive radio observations detect the southern jet for the first time, roughly coinciding with the southern EELR. The VLA images show a continuous inner jet connected to the outer east–west lobe, confirming the jet origin of the radio emission. Our kinematic analysis shows spatial correlations between the radio jet and the outflowing gas, supporting the jet-driven feedback mechanism. More interestingly, we observe enhanced velocity dispersion in the perpendicular direction along with a shell-like structure. Our Baldwin–Phillips–Telervich analysis shows that the [O III ] emission overlapping with the radio jet is consistent with the shock+precursor model, whereas in the perpendicular region, a pure shock model fits well with the observations, indicating jet-induced shocks. Radio observations indicate episodic AGN activity characterized by surface brightness and spectral index discontinuities. Overall, based on our findings, we propose a jet-driven feedback mechanism as one of the key factors in the formation of the EELR in NGC 5972. Future high-resolution radio observations will be crucial to further investigate the origin of the EELR and quantify the extent to which the jet influences its formation and evolution.

• Riseley, C. J.; Vernstrom, T.; Lovisari, L.; O’Sullivan, E.; Gastaldello, F. & Brienza, M. [Vis alle 29 forfattere av denne artikkelen] (2025). Relighting the fire in Hickson Compact Group (HCG) 15: Magnetised fossil plasma revealed by the SKA Pathfinders and Precursors. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 697. doi: 10.1051/0004-6361/202553890. Fulltekst i vitenarkiv Vis sammendrag

  In the context of the life cycle and evolution of active galactic nuclei (AGNs), environment plays a key role. In particular, the over-dense environments of galaxy groups, where dynamical interactions and bulk motions have significant impact, offer an excellent but under-explored window into the life cycles of AGNs and the processes that shape the evolution of relativistic plasma. Pilot survey observations with the Australian Square Kilometre Array Pathfinder (ASKAP) Evolutionary Map of the Universe (EMU) survey have recovered diffuse emission associated with the nearby ( z  = 0.0228) galaxy group HCG15, which was revealed to be strongly linearly polarised. We studied the properties of this emission in unprecedented detail to settle questions about its nature and its relation to the group-member galaxies. We performed a multi-frequency spectropolarimetric study of HCG15, incorporating our ASKAP EMU observations as well as new data from MeerKAT, the LOw-Frequency ARray (LOFAR), Giant Metrewave Radio Telescope (GMRT), and Karl G. Jansky Very Large Array (VLA), along with X-ray data from XMM-Newton and optical spectra from Himalayan Chandra Telescope (HCT). Our study confirms that the diffuse structure represents remnant emission from historic AGN activity that is likely to be associated with HCG15-D, some 80 − 86 Myr ago (based on an ageing analysis). We detected significant highly linearly-polarised emission from a diffuse ‘ridge-like’ structure with a highly ordered magnetic field. Our analysis suggests that this emission is generated by the draping of magnetic field lines in the intra-group medium (IGrM). Subsequent investigations with simulations would further improve our understanding of this phenomenon. We confirm that HCG15-C is a group-member galaxy. Finally, we report the detection of thermal emission associated with a background cluster at a redshift of z  ≈ 0.87 projected onto the IGrM of HCG15, which matches the position and redshift of the recent Sunyaev-Zel’dovich (SZ) detection of ACT-CL J0207.8+0209.

• Mondal, Santanu; Das, Mousumi; Khatun, Rubinur; Bansal, Karishma; Nath, Aniket & Taylor, Greg B. (2024). Detection of the Fe K lines from the binary AGN in 4C+37.11. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 691. doi: 10.1051/0004-6361/202450616. Fulltekst i vitenarkiv Vis sammendrag

  We report the discovery of the Fe K line emission at ∼6.62−0.06+0.06 keV with a width of ∼0.19−0.05+0.05 keV using two epochs of Chandra archival data for the nucleus of the galaxy 4C+37.11, which is known to host a binary supermassive black hole (BSMBH) system where the SMBHs are separated by ∼7 mas or ∼7pc. Our study reports the first detection of the Fe K line from a known binary AGN, which has an F-statistic value of 20.98 and a probability of 2.47 × 10−12. Stacking two spectra reveals another Fe K line component at ∼7.87−0.09+0.19 keV. Different model scenarios indicate that the lines originate from the combined effects of accretion disk emission and circumnuclear collisionally ionized medium. The observed low column density favors a gas-poor merger scenario, where the high temperature of the hot ionized medium may be associated with the shocked gas in the binary merger and not with star formation activity. The estimated total BSMBH mass and disk inclination are ∼1.5 × 1010 M⊙ and ≳75°, indicating that the BSMBH is probably a high-inclination system. We were not able to tightly constrain the spin parameter using the present data sets. Our results draw attention to the fact that detecting the Fe K line emissions from BSMBHs is important for estimating the individual SMBH masses and the spins of the binary SMBHs, as well as for exploring their emission regions.

• Khatun, Rubinur (2024). AGN Feedback Signatures in UV Emission. Galaxies. 12(2). doi: 10.3390/galaxies12020015. Fulltekst i vitenarkiv Vis sammendrag

  Supermassive black holes (SMBH) are believed to influence galaxy evolution through AGN (active galactic nuclei) feedback. Galaxy mergers are key processes of galaxy formation that lead to AGN activity and star formation. The relative contribution of AGN feedback and mergers to star formation is not yet well understood. In radio-loud objects, AGN outflows are dominated by large jets. However, in radio-quiet objects, outflows are more complex and involve jet, wind, and radiation. In this review, we discuss the signatures of AGN feedback through the alignment of radio and UV emissions. Current research on AGN feedback is discussed, along with a few examples of studies such as the galaxy merger system MRK 212, the radio-quiet AGN NGC 2639, and the radio-loud system Centaurus A. Multi-frequency observations of MRK 212 indicate the presence of dual AGN, as well as feedback-induced star-forming UV clumps. The fourth episode of AGN activity was detected in radio observations of the Seyfert galaxy NGC 2639, which also showed a central cavity of 6 kpc radius in CO and UV maps. This indicates that multi-epoch jets of radio-quiet AGN can blow out cold molecular gas, which can further reduce star formation in the center of the galaxies. Recent UV observations of Cen A have revealed two sets of stellar population in the northern star-forming region, which may have two different origins. Recent studies have shown that there is evidence that both positive and negative feedback can be present in galaxies at different scales and times. High-resolution, multi-band observations of large samples of different types of AGN and their host galaxies are important for understanding the two types of AGN feedback and their effect on the host galaxies. Future instruments like INSIST and UVEX will be able to help achieve some of these goals.

• Paswan, Abhishek; Das, Mousumi & Khatun, Rubinur (2024). An Accreting Supermassive Black Hole Buried in a Faint Dwarf Galaxy. Astrophysical Journal Letters. ISSN 2041-8205. 972(2). doi: 10.3847/2041-8213/ad7388. Fulltekst i vitenarkiv Vis sammendrag

  In the last decade, there have been several discoveries of active galactic nuclei (AGN) in dwarf galaxies including an AGN in an ultracompact dwarf galaxy with a black hole mass >106M⊙. However, finding a supermassive black hole (SMBH) in a dwarf low surface brightness (LSB) galaxy is rare. We report the discovery of a Seyfert type 2 class AGN that is associated with a nuclear SMBH of mass ∼6.5 × 106M⊙ in a dwarf LSB galaxy (μ0,r > 23.8 mag arcsec−2) that we denote by MJ0818+2257. The galaxy was previously thought to be an outlying emission blob around the large spiral galaxy LEDA 1678924. In our current analysis, which includes the detection of the optical counterpart of MJ0818+2257, we study its ionized gas kinematics and find that the dynamical mass within the ionized gas disk is ∼5.3 × 109M⊙. This is comparable to its stellar mass, which is ∼3 × 109M⊙, and suggests that MJ0818+2257 is moderately dark matter dominated within the stellar disk. The SMBH-mass-to-galaxy-stellar-mass ratio is MBH/M(*) > 0.022, which is high compared to disk galaxies. Our detection of an SMBH in a bulgeless LSB dwarf galaxy raises questions about the growth of SMBHs in low-luminosity galaxies and suggests the possibility of detecting heavy seed black holes from early epochs in LSB dwarf galaxies in the low-redshift Universe.

• Scialpi, M.; Mannucci, F.; Marconcini, C.; Venturi, G.; Pancino, E. & Marconi, A. [Vis alle 24 forfattere av denne artikkelen] (2024). MUSE adaptive-optics spectroscopy confirms dual active galactic nuclei and strongly lensed systems at sub-arcsec separation. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 690. doi: 10.1051/0004-6361/202347242. Fulltekst i vitenarkiv Vis sammendrag

  The novel Gaia multi peak (GMP) technique has proven to be able to successfully select dual and lensed active galactic nuclei (AGN) candidates at sub-arcsecond separations. Both populations are important because dual AGN represent one of the central, still largely untested, predictions of ΛCDM cosmology, and compact lensed AGN allow us to probe the central regions of the lensing galaxies. In this work, we present high-spatial-resolution spectroscopy of 12 GMP-selected systems. We used the adaptive-optics assisted integral-field spectrograph MUSE at the VLT to resolve each system and investigate the nature of each component. All targets show the presence of two components confirming the GMP selection. We classify 4 targets as dual AGN, 3 as lensed quasar candidates, and 5 as a chance alignment of a star and an AGN. With separations ranging from 0.30″ to 0.86″, these dual and lensed systems are among the most compact systems discovered to date at z > 0.5. This is the largest sample of distant dual AGN with sub-arcsecond separations ever presented in a single paper.

• Sebastian, Biny; Caproni, Anderson; Kharb, Preeti; Nayana, A.J.; Ali, Arshi & Khatun, Rubinur [Vis alle 9 forfattere av denne artikkelen] (2024). A VLBA-uGMRT search for candidate binary black holes: study of six X-shaped radio galaxies with double-peaked emission lines. Monthly notices of the Royal Astronomical Society. ISSN 0035-8711. 530(4), s. 4902–4919. doi: 10.1093/mnras/stae546. Fulltekst i vitenarkiv Vis sammendrag

  Identifying methods to discover dual active galactic nucleus (AGN) has proven to be challenging. Several indirect tracers have been explored in the literature, including X/S-shaped radio morphologies and double-peaked (DP) emission lines in the optical spectra. However, the detection rates of confirmed dual AGN candidates from the individual methods remain extremely small. We search for binary black holes (BBH) in a sample of six sources that exhibit both X-shaped radio morphology and DP emission lines using the Very Long Baseline Array (VLBA). Three out of the six sources show dual VLBA compact components, making them strong candidates for BBH sources. In addition, we present deep uGMRT images revealing the exquisite details of the X-shaped wings in three sources. We present a detailed precession modeling analysis of these sources. The black hole separations estimated from the simplistic geodetic precession model are incompatible with those estimated from emission line offsets and the VLBA separations. However, precession induced by a non-coplanar secondary black hole is a feasible mechanism for explaining the observed X-shaped radio morphologies and the black hole separations estimated from other methods. The black hole separations estimated from the double-peaked emission lines agree well with the VLBA compact component separations. Future multifrequency VLBA observations will be critical in ruling out or confirming the BBH scenario in the three galaxies with dual component detections.

• Hagedorn, Jan Bendix; Cicone, Claudia; Sarzi, M.; Saintonge, A.; Severgnini, P. & Vignali, C. [Vis alle 10 forfattere av denne artikkelen] (2024). Molecular gas scaling relations for local star-forming galaxies in the low-M* regime. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 687. doi: 10.1051/0004-6361/202449773. Fulltekst i vitenarkiv Vis sammendrag

  We derived molecular gas fractions (fmol = Mmol/M*) and depletion times (τmol = Mmol/SFR) for 353 galaxies representative of the local star-forming population with 108.5 M⊙ < M* < 1010.5 M⊙ drawn from the ALLSMOG and xCOLDGASS surveys of CO(2−1) and CO(1−0) line emission. By adding constraints from low-mass galaxies and upper limits for CO non-detections, we find the median molecular gas fraction of the local star-forming population to be constant at log fmol = −0.99−0.19+0.22, challenging previous reports of increased molecular gas fractions in low-mass galaxies. Above M* ∼ 1010.5 M⊙, we find the fmol versus M* relation to be sensitive to the selection criteria for star-forming galaxies. We tested the robustness of our results against different prescriptions for the CO-to-H2 conversion factor and different selection criteria for star-forming galaxies. The depletion timescale τmol weakly depends on M*, following a power law with a best-fit slope of 0.16 ± 0.03. This suggests that small variations in specific star formation rate (sSFR = SFR/M*) across the local main sequence of star-forming galaxies with M* < 1010.5 M⊙ are mainly driven by differences in the efficiency of converting the available molecular gas into stars. We tested these results against a possible dependence of fmol and τmol on the surrounding (group) environment of the targets by splitting them into centrals, satellites, and isolated galaxies, and find no significant variation between these populations. We conclude that the group environment is unlikely to have a large systematic effect on the molecular gas content of star-forming galaxies in the local Universe.

• Khatun, Rubinur; Das, M.; Kharb, P.; Yadav, J.; Mondal, C. & Rahna, P.T. (2024). Study of star formation in dual nuclei galaxies using UVIT observations. Monthly notices of the Royal Astronomical Society. ISSN 0035-8711. 528(3), s. 4432–4450. doi: 10.1093/mnras/stae318. Fulltekst i vitenarkiv Vis sammendrag

  ABSTRACT We have used the Ultraviolet Imaging Telescope (UVIT) aboard AstroSat to study star formation in a sample of nine dual nuclei galaxies with separations ⪅ 11 kpc, which is an expected outcome of galaxy mergers. To minimize the contribution of active galactic nuclei (AGN) emission, we have used mid-IR colour cut-offs and masked the AGN-dominated nuclei. The UV continuum slope (β) is used to calculate the internal extinction (AV) which ranges from 0.53 to 4.04 in the FUV band and 0.44 to 3.10 in the NUV band for the sample. We have detected 1−20 star-forming clumps in our sample galaxies. The extinction-corrected total FUV star formation rate (SFR) ranges from ∼0.35 to ∼32 M⊙ yr−1. Our analyses of AV, specific SFR (sSFR) show that dual nuclei sources are associated with dusty, star-forming galaxies. The FUV − NUV colour maps show redder colour in the nuclear and disc regions while bluer colour is observed in the outskirts of most galaxies which can be due to embedded dust or different stellar populations. We have found some signatures of possible stellar/AGN feedback like a ring of star formation, a redder ring around blue nuclei, etc. However, further observations are required to confirm this.

• Arroyave, Isabel Montoya; Cicone, Claudia; Andreani, P.; Weiss, A.; Breuck, C De & Lundgren, A. [Vis alle 11 forfattere av denne artikkelen] (2024). A possible relation between global CO excitation and massive molecular outflows in local ULIRGs. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 686. doi: 10.1051/0004-6361/202348292. Fulltekst i vitenarkiv Vis sammendrag

  Local ultra-luminous infrared galaxies (ULIRGs) have been observed to host ubiquitous molecular outflows, including the most massive and powerful ever detected. These sources have also exceptionally excited global, galaxy-integrated CO ladders. A connection between outflows and molecular gas excitation has however never been established, since previous multi-J CO surveys were limited in spectral resolution and sensitivity and so they could only probe the global molecular gas conditions. In this work, we address this question using new, ground-based, sensitive heterodyne spectroscopy of multiple CO rotational lines (up to CO(7−6)) in a sample of 17 local ULIRGs. We used the Atacama Pathfinder Experiment (APEX) telescope to survey the CO(Jup ≥ 4) lines at a high signal-to-noise ratio, and complemented these data with CO(Jup ≤ 3) APEX and Atacama Large Millimeter Array (ALMA and ACA) observations presented in Montoya Arroyave et al. (2023, A&A, 673, A13). We detected a total of 74 (out of 75) CO lines, with up to six transitions per source. The resulting CO spectral line energy distributions (SLEDs) show a wide range in gas excitation, in agreement with previous studies on ULIRGs. Some CO SLEDs peak at Jup ∼ 3, 4, which we classify as “lower excitation”, while others plateau or keep increasing up to the highest-J CO transition probed, and we classify these as “higher excitation”. Our analysis includes for completeness the results of CO SLED fits performed with a single large velocity gradient component, but our main focus is the investigation of possible links between global CO excitation and the presence of broad and/or high-velocity CO spectral components that can contain outflowing gas. We discovered an increasing trend of line width as a function of Jup of the CO transition, which is significant at the 4σ level and appears to be driven by the eight sources that we classified as higher excitation. We further analyzed such higher-excitation ULIRGs, by performing a decomposition of their CO spectral profiles into multiple components, and we derived CO ladders that are clearly more excited for the spectral components characterized by higher velocities and/or velocity dispersion. Because these sources are known to host widespread molecular outflows, we favor an interpretation whereby the highly excited CO-emitting gas in ULIRGs resides in galactic-scale massive molecular outflows whose emission fills a large fraction of the beam of our APEX high-J CO observations. On the other hand, our results challenge alternative scenarios for which the high CO excitation in ULIRGs can be explained by classical component of the interstellar medium, such as photon- or X-ray dominated regions around the nuclear sources.

• Mannucci, F.; Scialpi, M.; Ciurlo, A.; Yeh, S.; Marconcini, C. & Tozzi, G. [Vis alle 47 forfattere av denne artikkelen] (2023). GMP-selected dual and lensed AGNs: Selection function and classification based on near-IR colors and resolved spectra from VLT/ERIS, Keck/OSIRIS, and LBT/LUCI. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 680. doi: 10.1051/0004-6361/202346894. Fulltekst i vitenarkiv Vis sammendrag

  The Gaia Multipeak (GMP) technique can be used to identify large numbers of dual or lensed active galactic nucleus (AGN) candidates at subarcsec separation, allowing us to study both multiple supermassive black holes (SMBHs) in the same galaxy and rare, compact lensed systems. The observed samples can be used to test the predictions of the models of SMBH merging when (1) the selection function of the GMP technique is known, and (2) each system has been classified as a dual AGN, a lensed AGN, or an AGN/star alignment. Here we show that the GMP selection is very efficient for separations above 0.15″ when the secondary (fainter) object has a magnitude G  ≲ 20.5. We present the spectroscopic classification of five GMP candidates using VLT/ERIS and Keck/OSIRIS and compare them with the classifications obtained from (a) the near-IR colors of seven systems obtained with LBT/LUCI, and (b) the analysis of the total spatially unresolved spectra. We conclude that colors and integrated spectra can already provide reliable classifications of many systems. Finally, we summarize the confirmed dual AGNs at z  &gt;  0.5 selected by the GMP technique, and compare this sample with other such systems from the literature, concluding that GMP can provide a large number of confirmed dual AGNs at separations below 7 kpc.

• Jana, Arghajit; Chatterjee, Arka; Chang, Hsiang-Kuang; Nandi, Prantik; Khatun, Rubinur & Kumari, Neeraj [Vis alle 9 forfattere av denne artikkelen] (2023). Coronal properties of low-Accreting AGNs using Swift, XMM-Newton, and NuSTAR observations. Monthly notices of the Royal Astronomical Society. ISSN 0035-8711. 524(3), s. 4670–4687. doi: 10.1093/mnras/stad2140. Fulltekst i vitenarkiv
• Rao, Vaishnav V.; Kharb, P.; Khatun, Rubinur; Silpa, S.; Roy, N. & Sebastian, B. [Vis alle 10 forfattere av denne artikkelen] (2023). AGN feedback through multiple jet cycles in the Seyfert galaxy NGC 2639. Monthly notices of the Royal Astronomical Society. ISSN 0035-8711. 524(2), s. 1615–1624. doi: 10.1093/mnras/stad1901. Fulltekst i vitenarkiv
• Ciurlo, A.; Mannucci, F.; Yeh, S.; Amiri, A.; Carniani, S. & Cicone, Claudia [Vis alle 21 forfattere av denne artikkelen] (2023). New multiple AGN systems with subarcsec separation: Confirmation of candidates selected via the novel GMP method. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 671. doi: 10.1051/0004-6361/202345853. Fulltekst i vitenarkiv Vis sammendrag

  The existence of multiple active galactic nuclei (AGNs) at small projected distances on the sky is due to either the presence of multiple, inspiraling supermassive black holes, or to gravitational lensing of a single AGN. Both phenomena allow us to address important astrophysical and cosmological questions. However, few kiloparsec-separation multiple AGNs are currently known. Recently, the newly developed Gaia multi-peak (GMP) method provided numerous new candidate members of these populations. We present spatially resolved, integral-field spectroscopy of a sample of four GMP-selected multiple AGN candidates. In all of these systems, we detect two or more components with subarcsec separations. We find that two of the systems are dual AGNs, one is either an intrinsic triple or a lensed dual AGN, while the last system is a chance alignment of an AGN and a star. Our observations double the number of confirmed multiple AGNs at projected separations below 7 kpc at z  &gt; 0.5, present the first detection of a possible triple AGN in a single galaxy at z  &gt; 0.5, and successfully test the GMP method as a novel technique to discover previously unknown multiple AGNs.

Se alle arbeider i NVA