@article{20974, abstract = {Thus far, Lyman-α damping wings towards quasars have been used to probe the global ionization state of the foreground intergalactic medium (IGM). A new parametrization has demonstrated that the damping wing signature also carries local information about the distribution of neutral hydrogen (H I) in front of the quasar before it started shining. Leveraging a recently introduced Bayesian JAX-based Hamiltonian Monte Carlo inference framework, we derive constraints on the Lorentzian-weighted H I column density NDW H I , the quasar’s distance rpatch to the first neutral patch, and its lifetime tQ based on James Webb Space Telescope (JWST) Near Infrared Spectrograph (NIRSpec) spectra of the two z ∼ 7.5 quasars J1007+2115 and J1342+0928. After folding in model-dependent topology information, we find that J1007+2115 (and J1342+0928) is most likely to reside in a (xH1)= 0.32+0.22 −0.20 (0.58+0.23 −0.23) neutral IGM while shining for a remarkably short lifetime of log10 tQ/yr = 4.14+0.74 −0.18 (an intermediate lifetime of 5.64+0.25 −0.43) along a sightline with log10 NDW H I /cm−2 = 19.70+0.35 −0.86 (20.24+0.25 −0.22) and rpatch = 28.9+54.0 −14.4 cMpc (10.9+5.6−5.9 cMpc). In light of the potential presence of local absorbers in the foreground of J1342+0928 as has been recently suggested, we also demonstrate how the Lorentzian-weighted column density NDW H I provides a natural means for quantifying their contribution to the observed damping wing signal.}, author = {Kist, Timo and Hennawi, Joseph F. and Davies, Frederick B. and Bañados, Eduardo and Bosman, Sarah E.I. and Cai, Zheng and Eilers, Anna Christina and Fan, Xiaohui and Haiman, Zoltán and Jun, Hyunsung D. and Liu, Yichen and Yang, Jinyi and Wang, Feige}, issn = {1365-2966}, journal = {Monthly Notices of the Royal Astronomical Society}, number = {3}, publisher = {Oxford University Press}, title = {{First constraints on the local ionization topology in front of two quasars at z ∼ 7.5}}, doi = {10.1093/mnras/staf2219}, volume = {545}, year = {2026}, } @article{21712, abstract = {Supermassive black hole binary (SMBHB) systems are expected to form as a consequence of galaxy mergers. At subparsec separations, SMBHBs can be identified as quasars with periodic variability, with previous periodicity searches uncovering significant candidates. However, these searches focused primarily on sinusoidal signals, while theoretical models and hydrodynamical simulations predict that binaries produce more complex non-sinusoidal pulse shapes. Here we examine the efficacy of the Lomb–Scargle periodogram (LSP; one of the most popular tools for periodicity searches in unevenly sampled lightcurves) to detect periodicities with a sawtooth shape mimicking results of hydrodynamical simulations. We simulate idealized well-sampled lightcurves, lightcurves that mimic the data in the Palomar Transient Factory (PTF) analyzed in M. Charisi et al. (2016), and lightcurves that resemble our expectations for single-band data in the upcoming Legacy Survey of Space and Time (LSST) of the Rubin Observatory. We approximate quasar variability with a damped random walk (DRW) model, inject sinusoidal and sawtooth pulse shapes, and assess their statistical significance. We find that in the presence of red noise, the LSP detects a relatively low fraction of the sinusoidal signals (∼45%, ∼24%, and ∼23%, in the PTF-like, idealized, and LSST-like lightcurves, respectively). The fraction is significantly reduced for sawtooth periodicity (with only ∼9% in PTF-like and ∼1% in idealized and LSST-like lightcurves). These low recovery rates imply that previous searches have missed the large majority of binaries. They also have significant implications for the detection of SMBHBs in upcoming LSST necessitating the development of advanced tools that go beyond the simple LSP.}, author = {Lin, Allison and Charisi, Maria and Haiman, Zoltán}, issn = {1538-4357}, journal = {The Astrophysical Journal}, number = {2}, publisher = {IOP Publishing}, title = {{Lomb-scargle periodogram struggles with non-sinusoidal supermassive Black Hole binary signatures in quasar lightcurves}}, doi = {10.3847/1538-4357/ae29a7}, volume = {997}, year = {2026}, } @article{21713, abstract = {GW231123 represents the most massive binary–black hole merger detected to date, lying firmly within, or even above, the pair-instability mass gap. The component spins are both exceptionally high (a1 = 0.90 +0.10/-0.19, a2 = 0.80 +0.20/-0.51), which is difficult to explain with repeated mergers. Here we show that the black hole spin vectors are closely aligned with each other while significantly tilted relative to the binary’s orbital angular momentum, pointing to a common accretion-driven origin. We examine astrophysical formation channels capable of producing near-equal, high-mass, and mutually aligned spins consistent with GW231123—particularly binaries embedded in AGN disks and Population III remnants, which grew via coherent misaligned gas accretion. We further argue that other high-mass, high-spin events, e.g., GW190521, may share a similar evolutionary pathway. These findings underscore the critical role of sustained, coherent accretion in shaping the most extreme black hole binaries.}, author = {Bartos, Imre and Haiman, Zoltán}, issn = {2041-8213}, journal = {The Astrophysical Journal Letters}, number = {2}, publisher = {IOP Publishing}, title = {{Accretion is all you need: Black Hole spin alignment in merger GW231123 indicates accretion pathway}}, doi = {10.3847/2041-8213/ae2bff}, volume = {996}, year = {2026}, } @article{20193, abstract = {Understanding the rapid formation of supermassive black holes in the early Universe requires insights into stellar mass growth in host galaxies. Here we present NIRSpec rest-frame optical spectra and NIRCam imaging from JWST of two galaxies at z > 6, both hosting moderate-luminosity quasars. These galaxies exhibit Balmer absorption lines, like low-redshift post-starburst galaxies. Our analyses of the medium-resolution spectra and multiband photometry show that the bulk of the stellar mass (log(M*/M☉) ≥ 10.6) formed in starburst episodes at redshift 9 and 7. One of the galaxies shows a clear Balmer break and lacks spatially resolved Hα emission. It falls well below the star-formation main sequence at z = 6, indicating quiescence. The other is transitioning to quiescence; together, these massive galaxies are among the most distant post-starburst systems known. The blueshifted wings of the quasar [O iii] emission lines indicate quasar-driven outflow, which possibly influences star formation. Direct stellar velocity dispersion measurements reveal that one galaxy follows the local black hole mass versus σ* relation whereas the other is overmassive. The existence of massive post-starburst galaxies hosting billion-solar-mass black holes in short-lived quasar phases indicates that supermassive black holes and host galaxies played a principal role in each other’s rapid early formation.}, author = {Onoue, Masafusa and Ding, Xuheng and Silverman, John D. and Matsuoka, Yoshiki and Izumi, Takuma and Strauss, Michael A. and Ward, Charlotte and Phillips, Camryn L. and Ito, Kei and Andika, Irham T. and Aoki, Kentaro and Arita, Junya and Baba, Shunsuke and Bieri, Rebekka and Bosman, Sarah E.I. and Eilers, Anna Christina and Fujimoto, Seiji and Habouzit, Melanie and Haiman, Zoltán and Imanishi, Masatoshi and Inayoshi, Kohei and Iwasawa, Kazushi and Jahnke, Knud and Kashikawa, Nobunari and Kawaguchi, Toshihiro and Kohno, Kotaro and Lee, Chien Hsiu and Li, Junyao and Lupi, Alessandro and Lyu, Jianwei and Nagao, Tohru and Overzier, Roderik and Schindler, Jan Torge and Schramm, Malte and Scoggins, Matthew T. and Shimasaku, Kazuhiro and Toba, Yoshiki and Trakhtenbrot, Benny and Trebitsch, Maxime and Treu, Tommaso and Umehata, Hideki and Venemans, Bram and Vestergaard, Marianne and Volonteri, Marta and Walter, Fabian and Wang, Feige and Yang, Jinyi and Zhang, Haowen}, issn = {2397-3366}, journal = {Nature Astronomy}, pages = {1541--1552}, publisher = {Springer Nature}, title = {{A post-starburst pathway for the formation of massive galaxies and black holes at z > 6}}, doi = {10.1038/s41550-025-02628-1}, volume = {9}, year = {2025}, } @article{20250, abstract = {Population III stars are possible precursors to early supermassive black holes (BHs). The presence of soft UV Lyman–Werner (LW) background radiation can suppress Population III star formation in minihaloes and allow them to form in pristine atomic-cooling haloes. In the absence of molecular hydrogen (⁠H2⁠) cooling, atomic-cooling haloes enable rapid collapse with suppressed fragmentation. High background LW fluxes from preceding star-formation have been proposed to dissociate H2⁠. This flux can be supplemented by LW radiation from one or more Population III star(s) in the same halo, reducing the necessary background level. Here, we consider atomic-cooling haloes in which multiple protostellar cores form close to one another nearly simultaneously. We assess whether the first star’s LW radiation can dissociate nearby ⁠, enabling rapid accretion on to a nearby protostellar core, and the prompt formation of a second, supermassive star (SMS) from warm, atomically-cooled gas. We use a set of hydrodynamical simulations with the code enzo, with identical LW backgrounds centred on a halo with two adjacent collapsing gas clumps. When an additional large local LW flux is introduced, we observe immediate reductions in both the accretion rates and the stellar masses that form within these clumps. While the LW flux reduces the H2 fraction and increases the gas temperature, the halo core’s potential well is too shallow to promptly heat the gas to >1000 K and increase the second protostar’s accretion rate. We conclude that this internal LW feedback scenario is unlikely to facilitate SMS or massive BH seed formation.}, author = {Sullivan, James and Haiman, Zoltán and Kulkarni, Mihir and Visbal, Eli}, issn = {1365-2966}, journal = {Monthly Notices of the Royal Astronomical Society}, number = {2}, pages = {822--838}, publisher = {Oxford University Press}, title = {{Can supermassive stars form in protogalaxies due to internal Lyman-Werner feedback?}}, doi = {10.1093/mnras/staf1269}, volume = {542}, year = {2025}, } @article{20493, abstract = {We propose a formation pathway linking black holes (BHs) observed in gravitational-wave (GW) mergers, wide BH–stellar systems uncovered by Gaia, and accreting low-mass X-ray binaries (LMXBs). In this scenario, a stellar-mass BH binary undergoes isolated binary evolution and merges while hosting a distant, dynamically unimportant tertiary stellar companion. The tertiary becomes relevant only after the merger, when the remnant BH receives a GW recoil kick. Depending on the kick velocity and system configuration, the outcome can be: (1) a bright electromagnetic (EM) counterpart to the GW merger; (2) an LMXB; (3) a wide BH–stellar companion system resembling the Gaia BH population; or (4) an unbound isolated BH. Modeling the three-body dynamics, we find that ∼0.02% of LIGO–Virgo–KAGRA (LVK) mergers may be followed by an EM counterpart within ∼10 days, produced by tidal disruption of the star by the BH. The flare is likely brightest in the optical–UV and lasts for days to weeks; in some cases, partial disruption causes recurring flares with a period of ∼2 months. We further estimate that this channel can produce ∼1%–10% of Gaia BH systems in the Milky Way. This scenario provides the first physically motivated link between GW sources, Gaia BHs, and some X-ray binaries, and predicts a rare but robust pathway for EM counterparts to binary BH mergers, potentially detectable in LVK’s O5 run.}, author = {Naoz, Smadar and Haiman, Zoltán and Quataert, Eliot and Holzknecht, Liz}, issn = {2041-8213}, journal = {The Astrophysical Journal Letters}, number = {1}, publisher = {IOP Publishing}, title = {{Triples as links between binary Black Hole mergers, their electromagnetic counterparts, and galactic Black Holes}}, doi = {10.3847/2041-8213/ae0a20}, volume = {992}, year = {2025}, } @article{20651, abstract = {The origin of merging binary black holes detected through gravitational waves remains a fundamental question in astrophysics. While stellar evolution imposes an upper mass limit of ∼50⁢𝑀⊙ for black holes, some observed mergers—most notably GW190521—involve significantly more massive components, suggesting alternative formation channels. Here we investigate the maximum masses attainable by black hole mergers within active galactic nucleus (AGN) disks. Using a comprehensive semianalytic model incorporating 27 binary and environmental parameters, we explore the role of AGN disk conditions in shaping the upper end of the black hole mass spectrum. We find that an AGN disk lifetime is the dominant factor, with high-mass mergers (≳200⁢𝑀⊙) only possible if disks persist for ≳40  Myr. The joint electromagnetic observation of an AGN-assisted merger could therefore lead to a direct measurement of the age of an AGN disk.}, author = {Xue, Ling Qin and Tagawa, Hiromichi and Haiman, Zoltán and Bartos, Imre}, issn = {2470-0029}, journal = {Physical Review D}, number = {6}, publisher = {American Physical Society}, title = {{What determines the maximum mass of AGN-assisted black hole mergers?}}, doi = {10.1103/5m1n-qh9v}, volume = {112}, year = {2025}, } @article{20686, abstract = {Emission from two massive black holes (MBHs) bound in a close binary is expected to be modulated by different processes, such as the Doppler boost due to the orbital motion, accretion rate variability generated by the interaction with a circumbinary disc, and binary gravitational self-lensing. When the binary is compact enough, the two black holes are thought to be surrounded by a common broad-line region that reprocesses the impinging periodically varying ionising flux, creating broad emission lines with variable line shapes. Therefore, the study of broad emission line variability through multi-epoch spectroscopic campaigns is of paramount importance for the unambiguous identification of a binary. In this work, we study the response of a disc-like broad-line region to the Doppler-boosted ionising flux emitted by sub-milliparsec MBH binaries on a circular orbit and compare it with the response of a broad-line region illuminated by a single MBH with a periodically but isotropically varying intrinsic luminosity. We show that in the binary case, the time lags of the blue and red wings of the broad emission lines, arising from diametrically opposite sides of the circumbinary disc, are out of phase by half of the binary’s orbital period, as they each respond to the periodic ‘lighthouse’ modulation from the binary’s continuum emission. This asymmetric time lag represents a new binary signature that cannot be mimicked by a single MBH.}, author = {Bertassi, Lorenzo and Sottocorno, Erika and Rigamonti, Fabio and D’Orazio, Daniel and Eracleous, Michael and Haiman, Zoltán and Dotti, Massimo}, issn = {1432-0746}, journal = {Astronomy & Astrophysics}, publisher = {EDP Sciences}, title = {{Testing compact massive black hole binary candidates through multi-epoch spectroscopy}}, doi = {10.1051/0004-6361/202554574}, volume = {702}, year = {2025}, } @article{19497, abstract = {The stochastic gravitational wave (GW) background recently discovered by several pulsar timing array experiments is consistent with arising from a population of coalescing super-massive black hole binaries. The amplitude of the background is somewhat higher than expected in most previous population models or from the local mass density observations. Such binaries are expected to be produced in galaxy mergers, which are also thought to trigger bright quasar activity. Under the assumptions that (i) a fraction fbin∼1 of all quasars are associated with mergers, (ii) the typical quasar lifetime is tQ∼108 yr, and (iii) adopting Eddington ratios fEdd∼0.25 for the luminosity of quasars, we compute the GW background associated directly with the empirically measured quasar luminosity function. This approach bypasses the need to model the cosmological evolution of black holes or galaxy mergers from simulations or semi-analytical models. We find the amplitude matching the value measured by NANOGrav. Our results are consistent with most quasars being associated with black hole binaries and being the sources of the GW background, and imply a joint constraint on tQ, fEdd and the typical mass ratio q≡M2/M1. The signal in this case would be dominated by relatively distant ∼109M⊙ sources at z≈2−3, at the peak of quasar activity. Similarly to other models, our results remain in tension with the local super-massive black hole mass density.}, author = {Kis-Tóth, Ágnes and Haiman, Zoltán and Frei, Zsolt}, issn = {1361-6382}, journal = {Classical and Quantum Gravity}, number = {7}, publisher = {IOP Publishing}, title = {{Can quasars, triggered by mergers, account for NANOGrav’s stochastic gravitational wave background?}}, doi = {10.1088/1361-6382/adbda6}, volume = {42}, year = {2025}, } @article{19638, abstract = {The James Webb Space Telescope has revealed low-luminosity active galactic nuclei at redshifts of z ≳ 4–7, many of which host accreting massive black holes (BHs) with BH-to-galaxy mass (MBH/M⋆) ratios exceeding the local values by more than an order of magnitude. The origin of these overmassive BHs remains unclear but requires potential contributions from heavy seeds and/or episodes of super-Eddington accretion. We present a growth model coupled with dark matter halo assembly to explore the evolution of the MBH/M⋆ ratio under different seeding and feedback scenarios. Given the gas inflow rates in protogalaxies, BHs grow episodically at moderate super-Eddington rates, and the mass ratio increases early on, despite significant mass loss through feedback. Regardless of seeding mechanisms, the mass ratio converges to a universal value ∼0.1–0.3, set by the balance between gas feeding and star formation efficiency in the nucleus. This behavior defines an attractor in the MBH–M⋆ diagram, where overmassive BHs grow more slowly than their hosts, while undermassive seeds experience rapid growth before aligning with the attractor. We derive an analytical expression for the universal mass ratio, linking it to feedback strength and halo growth. The convergence of evolutionary tracks erases seeding information from the mass ratio by z ∼ 4–6. Detecting BHs with ∼105−6 M⊙ at higher redshifts that deviate from the convergence trend would provide key diagnostics of their birth conditions.}, author = {Hu, Haojie and Inayoshi, Kohei and Haiman, Zoltán and Ho, Luis C. and Ohsuga, Ken}, issn = {2041-8213}, journal = {The Astrophysical Journal Letters}, number = {2}, publisher = {IOP Publishing}, title = {{The convergence of heavy and light seeds to overmassive black holes at cosmic dawn}}, doi = {10.3847/2041-8213/adc680}, volume = {983}, year = {2025}, } @article{19699, abstract = {We demonstrate that gas disks around binary systems might deliver gas to the binary components only when the circumbinary disk is relatively warm. We present new grid-based hydrodynamics simulations, performed with the binary on the grid and a locally isothermal equation of state, in which the binary is seen to functionally "stop accreting" if the orbital Mach number in the disk exceeds a threshold value of about 40. Above this threshold, the disk continues to extract angular momentum from the binary orbit, but it delivers very little mass to the black holes and instead piles up mass in a ring surrounding the binary. This ring will eventually become viscously relaxed and deliver mass to the binary at the large-scale inflow rate. However, we show that the timescale for such relaxation can far exceed the implied binary lifetime. We demonstrate that the ability of a binary–disk system to equilibrate is dependent on the efficiency at which accretion streams deposit mass onto the binary, which, in turn is highly sensitive to the thermodynamic conditions of the inner disk. If disks around massive black hole binaries do operate in such nonaccreting regimes, it suggests these systems may be dimmer than their single black hole counterparts but could exhibit dramatic rebrightening after the black holes inspiral and merge. This dimming begins in the UV/optical and could completely choke high-energy emission, such that these systems would likely be intrinsically X-ray weak with reddened continua, potentially resembling the spectra of "little red dots" recently identified in JWST observations.}, author = {Tiede, Christopher and Zrake, Jonathan and Macfadyen, Andrew and Haiman, Zoltán}, issn = {1538-4357}, journal = {The Astrophysical Journal}, number = {2}, publisher = {IOP Publishing}, title = {{Suppressed accretion onto massive black hole binaries surrounded by thin disks}}, doi = {10.3847/1538-4357/adc727}, volume = {984}, year = {2025}, } @article{21121, abstract = {The relation between the masses of supermassive black holes (SMBHs) and their host galaxies encodes information on their mode of growth, especially at the earliest epochs. The James Webb Space Telescope (JWST) has opened such investigations by detecting the host galaxies of active galactic nuclei (AGN) and more luminous quasars within the first billion years of the Universe (z ≳ 6). Here, we evaluate the relation between the mass of SMBHs and the total stellar mass of their host galaxies using a sample of nine quasars at 6.18 ≤ z ≤ 6.4 from the Subaru High-z Exploration of Low-luminosity Quasars survey with NIRCam and NIRSpec observations. We find that the observed location of these quasars in the SMBH–galaxy mass plane (logMBH/M 8–9; logM*/M 9.5–11) is consistent with a nonevolving intrinsic mass relation with dispersion (0.80 +0.23 -0.28 dex) higher than the local value (∼0.3–0.4 dex) of their more massive descendants. Our analysis is based on a forward model of systematics and includes a consideration of the impact of selection effects and measurement uncertainties with an assumption on the slope of the mass relation. While degeneracies between parameters persist, the best-fit solution has a reasonable AGN fraction (2.3%) of galaxies at z ∼ 6 with an actively growing UV-unobscured black hole. In particular, models with a substantially higher normalisation in MBH would require an unrealistically low intrinsic dispersion (∼0.22 dex). Consequently, our results predict a large population of AGN at lower black hole masses, as are now just starting to be discovered in focused efforts with JWST.}, author = {Silverman, John David and Li, Junyao and Ding, Xuheng and Onoue, Masafusa and Strauss, Michael A. and Matsuoka, Yoshiki and Izumi, Takuma and Jahnke, Knud and Treu, Tommaso and Volonteri, Marta and Phillips, Camryn L. and Andika, Irham T. and Aoki, Kentaro and Arita, Junya and Baba, Shunsuke and Bosman, Sarah E. I. and Eilers, Anna-Christina and Fan, Xiaohui and Fujimoto, Seiji and Habouzit, Melanie and Haiman, Zoltán and Imanishi, Masatoshi and Inayoshi, Kohei and Iwasawa, Kazushi and Kashikawa, Nobunari and Kawaguchi, Toshihiro and Lee, Chien-Hsiu and Lupi, Alessandro and Nagao, Tohru and Schindler, Jan-Torge and Schramm, Malte and Shimasaku, Kazuhiro and Toba, Yoshiki and Trakhtenbrot, Benny and Umehata, Hideki and Vestergaard, Marianne and Walter, Fabian and Wang, Feige and Yang, Jinyi}, issn = {2041-8213}, journal = {The Astrophysical Journal Letters}, number = {2}, publisher = {IOP Publishing}, title = {{SHELLQs–JWST perspective on the intrinsic mass relation between supermassive black holes and their host galaxies at z > 6}}, doi = {10.3847/2041-8213/ae279c}, volume = {995}, year = {2025}, } @article{21122, abstract = {The multimessenger combination of gravitational waves (GWs) from merging massive black hole binaries (MBHBs) and the electromagnetic (EM) counterpart from the surrounding circumbinary disc (CBD) will open avenues to new scientific pursuits. In order to realize this science, we need to correctly localize the host galaxy of the merging MBHB. Multiwavelength, time-dependent EM signatures can greatly facilitate the identification of the unique EM counterpart among many sources in LISA’s localization volume. To this end, we studied merging unequal-mass MBHBs embedded in a CBD using high-resolution 2D simulations, with a $\Gamma$-law equation of state, incorporating viscous heating, shock heating, and radiative cooling. We simulate each binary starting from before it decouples from the CBD until just after the merger. We compute EM signatures and identify distinct features before, during, and after the merger. We corroborate previous findings of a several orders of magnitude drop in the thermal X-ray luminosity near the time of merger, but with delayed timing compared to an equal-mass system. The source remains X-ray dark for hours post-merger. Our main results are a potential new signature of a sharp spike in the thermal X-ray emission just before the tell-tale steep drop occurs. This feature may further help to identify EM counterparts of LISA’s unequal MBHBs before merger without the need for extensive pre-merger monitoring. Additionally, we find a role-reversal in which the primary out-accretes the secondary during late inspiral, which may diminish signatures originating from Doppler modulation.}, author = {Krauth, Luke Major and Davelaar, Jordy and Haiman, Zoltán and Westernacher-Schneider, John Ryan and Zrake, Jonathan and MacFadyen, Andrew}, issn = {1365-2966}, journal = {Monthly Notices of the Royal Astronomical Society}, number = {3}, pages = {2670--2685}, publisher = {Oxford University Press}, title = {{Thermal X-ray signatures in late-stage unequal-mass massive black hole binary mergers}}, doi = {10.1093/mnras/staf1583}, volume = {543}, year = {2025}, } @article{21123, abstract = {We present a study of the late-time interaction between supermassive black hole binaries and retrograde circumbinary disks during the period of gravitational wave-driven inspiral. While mergers in prograde disks have received extensive study, retrograde disks offer distinct dynamics that could promote mergers and produce unique observational signatures. Through 2D numerical hydrodynamical simulations, we explore the process of binary-disk decoupling, where the binary’s orbital decay rate is faster than the disk’s viscous response rate. We find the point of decoupling to be comparable in prograde and retrograde disks, suggesting that any associated electromagnetic (EM) signatures will be produced at comparable times preceding the merger. However, we find smaller central cavities for retrograde disks, likely leading to higher-frequency EM emissions and shorter postmerger rebrightening timescales compared to their prograde counterparts. Retrograde disks form intrabinary bridges, which are prone to instabilities when the viscosity is low. These instabilities manifest as quasiperiodic flares in the accretion rate, which may produce distinctive EM signatures for retrograde disks.}, author = {O’Neill, David and Tiede, Christopher and D’Orazio, Daniel J. and Haiman, Zoltán and MacFadyen, Andrew}, issn = {1538-4357}, journal = {The Astrophysical Journal}, number = {2}, publisher = {IOP Publishing}, title = {{Gravitational wave decoupling in retrograde circumbinary disks}}, doi = {10.3847/1538-4357/ae0ca8}, volume = {993}, year = {2025}, } @article{21124, abstract = {The advent of the James Webb Space Telescope (JWST) has opened new horizons in the study of quasar host galaxies during the reionization epoch (z > 6). Building upon our previous initial measurements of stellar light from two quasar host galaxies at these redshifts, we now report the detection of the stellar light from the full Cycle 1 sample of 12 distant moderate-luminosity quasar (M1450 > −24 mag) host galaxies at z > 6 from the Hyper Suprime-Cam Subaru Strategic Program. Using JWST/NIRCam observations at 1.5 and 3.6 μm combined with 2D image decomposition analysis, we successfully detect the host galaxies in 11 of the 12 targets, underscoring the high detection rates achievable with moderate-luminosity quasars. Based on two-band photometry and spectral energy distribution fitting, we find that our host galaxies are massive, with log M*/M⊙ = 9.5–11.0. The effective radii range from 0.6 to 3.2 kpc, comparable to the sizes of inactive galaxies with similar masses at z ∼ 6 as measured with imaging from COSMOS-Web. Intriguingly, the two quasar hosts with post-starburst features, which reside at the high-mass end of our sample and exhibit relatively compact morphologies, have similar size and stellar mass surface densities to quiescent galaxies at z ∼ 4–5. These findings suggest that the so-called galaxy compaction scenario is already in place at the reionization epoch, in which gas inflows during starburst phases drive centrally concentrated star formation followed by rapid quenching, bridging the structural transition of massive galaxies from relatively extended star-forming disks to compact quiescent systems.}, author = {Ding, Xuheng and Onoue, Masafusa and Silverman, John D. and Matsuoka, Yoshiki and Izumi, Takuma and Strauss, Michael A. and Yang, Lilan and Jahnke, Knud and Phillips, Camryn L. and Treu, Tommaso and Andika, Irham T. and Aoki, Kentaro and Arita, Junya and Baba, Shunsuke and Bosman, Sarah E. I. and Eilers, Anna-Christina and Fujimoto, Seiji and Haiman, Zoltán and Imanishi, Masatoshi and Inayoshi, Kohei and Iwasawa, Kazushi and Kartaltepe, Jeyhan and Kashikawa, Nobunari and Kawaguchi, Toshihiro and Li, Junyao and Lee, Chien-Hsiu and Lupi, Alessandro and Schindler, Jan-Torge and Schramm, Malte and Shimasaku, Kazuhiro and Shuntov, Marko and Tanaka, Takumi S. and Toba, Yoshiki and Trakhtenbrot, Benny and Umehata, Hideki and Vestergaard, Marianne and Wang, Feige and Yang, Jinyi}, issn = {1538-4357}, journal = {The Astrophysical Journal}, number = {1}, publisher = {IOP Publishing}, title = {{SHELLQs-JWST unveils the host galaxies of 12 quasars at z > 6}}, doi = {10.3847/1538-4357/ae045b}, volume = {993}, year = {2025}, } @article{21724, abstract = {The next generation of weak-gravitational-lensing surveys has the potential to place stringent constraints on cosmological parameters. However, their analysis is limited by systematics such as the intrinsic alignments of galaxies, which alter weak-lensing convergence and can lead to biases in cosmological parameter estimations. For the first time, in this work, we investigate the impact of intrinsic alignments on non-Gaussian statistics of the weak-lensing field using galaxy shapes derived from the IllustrisTNG hydrodynamical simulation. We create two catalogs of ray-traced convergence maps: one that includes the measured intrinsic shape of each galaxy and another where all galaxies are randomly rotated to eliminate intrinsic alignments. We compare a range of weak-lensing statistics between the two catalogs, including the shear–shear correlation function, the map-level angular power spectrum, one-point, peak count, and minimum distribution functions, and Minkowski functionals. For each statistic, we assess the level of statistical distinguishability between catalogs for a set of future survey angular areas. Our results reveal strong small-scale correlation in the alignment of galaxies and statistically significant boosts in weak-lensing convergence in both positive and negative directions for high-significance peaks and minima, respectively. We note that our analysis is at a fixed number density of ˜ 5 arcmin^-2, drawn from a single realization of initial conditions, and does not include observational uncertainties or supersample covariance contributions. Weak-lensing analyses utilizing non-Gaussian statistics must account for intrinsic alignments to avoid significantly compromised cosmological inferences.}, author = {Lee, Max E. and Haiman, Zoltán and Pandey, Shivam and Genel, Shy}, issn = {1538-4357}, journal = {The Astrophysical Journal}, number = {1}, publisher = {IOP Publishing}, title = {{The effect of intrinsic alignments on weak-lensing statistics in hydrodynamical simulations}}, doi = {10.3847/1538-4357/ae1ca7}, volume = {996}, year = {2025}, }