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Physics Astrophysics Astrophysics of Galaxies

astro-ph.GA Watch Astrophysics of Galaxies

Friday 11 September

Astrophysics of Galaxies

Heavy Seed Black Hole Growth in Metal-Enriched Halos through Disk-Induced Stellar Disruptions: A Semi-Analytical Modelling

Zijian Wang, Zhili Wang, Yiqiu Ma et al. (+4 more)

Recent simulations suggest that heavy seed black holes may form in weakly metal-enriched atomic cooling halos, where the supermassive-star progenitor and small-scale stellar fragments emerge nearly coevally. In this picture, the newly born heavy seed is naturally embedded in a metal-enriched Pop~I/II nuclear star cluster rather than in an isolated pristine environment. We investigate whether disk-induced tidal disruption events (TDEs) from these Pop~I/II stars can provide an efficient and sustained growth channel for heavy seed black holes. We construct a semi-analytical model for stellar orbital damping, disk capture, migration, and tidal disruption around a heavy seed black hole, and incorporate the resulting disk-induced TDE contribution into cosmological merger trees with baryonic and metallicity evolution. Heavy seed host halos are selected from atomic cooling halos with $Z\lesssim10^{-3}Z_\odot$ that satisfy either a rapid gas-inflow criterion or a strong Lyman–Werner radiation criterion. We find that disk-induced Pop~I/II TDEs can dominate the early growth of heavy seeds: the median black hole mass grows from $\sim10^4\,M_\odot$ to $\sim10^5\,M_\odot$ within the first $\sim0.1$ Gyr after seed formation, and reaches several $10^5\,M_\odot$ by $\sim0.2$ Gyr. The cumulative mass supplied by TDEs initially exceeds that from gas accretion and remains comparable over the first $\sim200$ Myr. Including disk-induced TDEs shifts the black hole population toward higher masses, increases the abundance of massive black holes at $z\sim9$–10, and produces larger black hole-to-stellar mass ratios. This channel helps alleviate, but does not fully remove, the tension between heavy-seed models and the most extreme high-redshift black hole candidates, suggesting that additional growth mechanisms may still be required.
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All authors Zijian Wang, Zhili Wang, Yiqiu Ma, Boyuan Liu, Zheng Cai, Mengye Wang, Qingwen Wu

Astrophysics of Galaxies

E-INSPIRE - II. Finding relics from wide-sky multi-band surveys: A proof-of-concept machine learning regression algorithm

Charles Rosen, Chiara Spiniello, John Mills et al. (+7 more)

In this second paper of the E-INSPIRE series, we train a machine-learning-based regression on $\sim430$ nearby ($z<0.5$) ultra-compact massive galaxies (UCMGs) with spectroscopically inferred kinematics, stellar population parameters and a measured “degree of relicness” (DoR). Our goal is to investigate how robustly the spectroscopically inferred DoR can be statistically reconstructed from observable galaxy properties, and to explore the potential applicability of this framework to future wide-area surveys. We test several regression algorithms finding that Support Vector Regression (SVR) provides the best performance. We explore multiple input feature configurations, from a minimal set including only age and metallicity to more comprehensive ones incorporating stellar population parameters, kinematics, structural properties, and the associated uncertainties. All tested models achieve similarly high performance on the training set ($R^2\ge0.81$), except for the minimal configuration ($R^2\sim0.78$). When evaluated on an independent INSPIRE sample of 52 UCMGs, the predictive power remains robust, although with increased model-to-model variation. The DoR distribution shows three regimes, with low (DoR$<0.3$) and high (DoR$>0.6$) values sparsely populated, leading to mild regression shrinkage toward intermediate values. However, this behaviour enables a conservative selection strategy: galaxies with predicted DoR$\ge0.6$ are strongly biased toward genuine extreme relics, making them prime targets for follow-up observations. This proof-of-concept confirms that the spectroscopically inferred DoR is robustly connected to observable stellar population and kinematical properties, and provides a first step toward future relic-candidate selection strategies in large photometric and spectroscopic surveys.
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All authors Charles Rosen, Chiara Spiniello, John Mills, Alexey Sergeyev, Vladyslav Khramtsov, Anna Ferré-Mateu, Johanna Hartke, Michalina Maksymowicz-Maciata, Malgorzata Siudek, Crescenzo Tortora

Astrophysics of Galaxies · Cross-listed from astro-ph.SR

Magnetic Fields and Asymmetric Accretion in the Class 0 Protostellar System L1527 IRS

Hanju Nam, Woojin Kwon, Youngwoo Choi et al. (+2 more)

Magnetic fields play a crucial role in regulating the collapse of dense molecular clouds, shaping the early stages of protostellar evolution. We present polarization observations in submillimeter wavelengths with the SCUBA-2/POL-2 instrument on James Clerk Maxwell Telescope toward the Class 0 protostellar system L1527 IRS (IRAS 04368+2557). The magnetic field morphology varies across the core of L1527 IRS. Magnetic fields in the eastern region are perpendicular to the outflow axis, while those in the western region show a pinched morphology, overall aligned with the outflow cavity. These distinct bipolar outflow regions also have a clear color difference in near infrared observed by James Webb Space Telescope. In addition, the spectral index derived from 450 {\mu}m and 850 {\mu}m observations reveals that the northwestern region of the protostellar system is colder and denser compared to the southeastern region. Furthermore, in the large-scale structures and magnetic fields revealed by Herschel and Planck, we find a ~0.1 pc scale filamentary structure parallel to the large-scale magnetic fields in the eastern region and a relatively isotropic mass distribution in the western region. Based on these results, we propose an accretion scenario of the protostellar system in which an asymmetric mass distribution causes the distinct features observed in near-infrared and submillimeter wavelengths.
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All authors Hanju Nam, Woojin Kwon, Youngwoo Choi, Ian W. Stephens, Leslie W. Looney

Astrophysics of Galaxies

The constrainability of galaxy positions in the $M_*$ – SFR plane from SED fitting

Sabine Bellstedt, Aaron S. G. Robotham, Luke J. M. Davies et al. (+2 more)

Using a sample of 6,029 $z<0.06$ galaxies from the GAMA survey, we characterise the spread of galaxy property inferences on the M$_*$ – SFR plane via Spectral Energy Distribution (SED) fitting. We analyse 24 different model configurations using the stellar population library code ProGeny, and the SED-fitting code ProSpect, and quantify how modelling assumptions affect inferred stellar masses, star formation rates, and the resulting classification of galaxies. We find that the reproducibility of inferred galaxy positions depends strongly on location within the $M_*$ – SFR plane, with uncertainties increasing dramatically below $\log_{10}(\rm{sSFR}/\rm{yr}^{-1}) \sim -11$. This boundary closely tracks the transition between robustly and poorly constrained SFR estimates, regardless of whether SFRs are derived from SED fitting or H$_{\alpha}$ measurements. We find that star-bursting galaxies cannot be robustly isolated from SED fitting alone, while the separation of star-forming and passive galaxies is most consistently conducted by a cut in sSFR, rather than a dex cut relative to either a curved or linear SFS (Star Forming Sequence). We further show that transitioning (or Green Valley) selections using SED fitting are highly unstable, with only $\sim$25% of the sample being repeatedly selected, on average.
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All authors Sabine Bellstedt, Aaron S. G. Robotham, Luke J. M. Davies, Luca Cortese, Simon P. Driver

Astrophysics of Galaxies · Cross-listed from astro-ph.EP

KMT-2026-BLG-0083L: A Two-Jovian-Planet System Orbiting an M Dwarf Discovered by Microlensing

Cheongho Han, Chung-Uk Lee, Zhixing Li et al. (+65 more)

We present the analysis of the microlensing event KMT-2026-BLG-0083, which was independently detected by the KMTNet, OGLE, and PRIME surveys and also monitored by the DREAMS survey. The combined data provide dense coverage of two distinct short-duration anomalies in the light curve that cannot be reproduced by a standard binary-lens model. Independent analyses of the two anomalies indicate that each is produced by a planetary companion to the lens, motivating a triple-lens interpretation. The modeling yields two pairs of degenerate solutions arising from the well-known inner–outer degeneracy, with each pair exhibiting two local solutions depending on whether the source passes above or below the distant planetary companion. The preferred model indicates two giant planets with mass ratios $q_2=(5.25\pm 0.08)\times 10^{-3}$ and $q_3=(3.04\pm 0.24)\times10^{-3}$ orbiting a common host. Bayesian analysis indicates that the host is an M-dwarf star with a mass of $0.48^{+0.36}_{-0.28}~M_\odot$, hosting two giant planets with masses of $2.65^{+1.96}_{-1.55}~M_{\rm J}$ and $1.54^{+1.14}_{-0.90}~M_{\rm J}$. The projected planet–host separations are $10.6^{+1.7}_{-2.2}$~au and $1.7^{+0.3}_{-0.3}$~au, placing the inner planet near the host's snow line and the outer planet at a substantially larger separation. Thus, KMT-2026-BLG-0083L becomes the seventh confirmed multiple-planet system discovered through gravitational microlensing, providing another example of a cold giant planetary system orbiting a subsolar-mass star.
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All authors Cheongho Han, Chung-Uk Lee, Zhixing Li, Weicheng Zang, Andrzej Udalski, Ian A. Bond, Yoon-Hyun Ryu, Steve Heathcote, Michael D. Albrow, Sun-Ju Chung, Andrew Gould, Youn Kil Jung, Kyu-Ha Hwang, Hongjing Yang, Yossi Shvartzvald, In-Gu Shin, Doeon Kim, Dong-Jin Kim, Byeong-Gon Park, Richard W. Pogge, Qiyue Qian, Yaosong Yu, Yuchen Tang, Yuxin Shang, Tomas Ahumada, imothy Abbott, Guillermo Damke, Konstantina Boutsia, Alfredo Zenteno, Shude Mao, Andong Xu, Przemek Mróz, Michał K. Szymański, Jan Skowron, Radosław Poleski, Igor Soszyński, Paweł Pietrukowicz, Szymon Kozłowski, Krzysztof A. Rybicki, Patryk Iwanek, Krzysztof Ulaczyk, Marcin Wrona, Mariusz Gromadzki, Mateusz J. Mróz, David P. Bennett, Aparna Bhattacharya, Kotaro Daimon, Ryusei Hamada, Yuki Hirao, Shuma Makida, Stela Ishitani Silva, Shota Miyazaki, Tutumi Nagai, Seiya Nakayama, Kansuke Nunota, Ryo Ogawa, Ryunosuke Oishi, Hideaki Ose, Nicholas J. Rattenbury, Yuki K. Satoh, Takahiro Sumi, Daisuke Suzuki, Motohide Tamura, Takuto Tamaoki, Sean K. Terry, Chihiro Ueda, Aikaterini Vandorou, Hibiki Yama

Astrophysics of Galaxies

A systematic study of the long-term mid-infrared color variations of Seyfert 1 galaxies

Jiahua Wu, Liming Dou, Zhining Chen et al. (+7 more)

We present a comparative analysis of long-term mid-infrared (MIR) color variations (MCVs) for 1,977 narrow-line Seyfert 1 (NLSy1) and 4,113 broad-line Seyfert 1 (BLSy1) galaxies at $z < 0.3$. Using 14 years of WISE and NEOWISE data, we quantify the correlation between $W1-W2$ color and $W1$ magnitude. We categorize sources into bluer-when-brighter (BWB), redder-when-brighter (RWB), and weak/no MCV populations. Our results show that the MCV properties of BLSy1s are consistent with those of NLSy1s. This suggests that host-contaminated dust reprocessing is a universal mechanism across Seyfert 1s. Bolometric luminosity ($\Lbol$) is the primary driver of MCV behavior. However, at fixed $\Lbol$, the fraction of RWB sources decreases with increasing Eddington ratio ($\REdd$). This reveals a secondary dependence on the accretion state. Ensemble structure function analysis further shows that higher-$\REdd$ sources exhibit flatter structure functions at a given $\Lbol$, indicating smaller dust torus radii. These findings suggest that the central engine's radiation and accretion state shape the circumnuclear dust geometry. Radio-loud sources follow the same trends as radio-quiet counterparts, implying that jet emission does not significantly impact long-term MIR variability. Finally, modified blackbody modeling indicates that grains with sizes $a \gtrsim 0.1~\mu$m are responsible for the observed MCVs. Our results establish a unified framework for MCVs in Seyfert~1s, where the Eddington ratio modulates both variability patterns and the physical scale of the dust torus. Furthermore, given the similarity between the MCV distributions of CLAGNs and RWB sources, we estimate that $\lesssim 6\%$ of Seyfert~1s may be CLAGN candidates, offering a potential MIR-based pre-selection.
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All authors Jiahua Wu, Liming Dou, Zhining Chen, Fupeng Zhang, Luis C. Ho, Yanli Ai, Tinggui Wang, Xinwen Shu, Ning Jiang, Junfeng Wang

Astrophysics of Galaxies · Cross-listed from astro-ph.HE

A Localized Current-Sheet Magnetic-Diffusion and Heating Prescription for Ideal-GRMHD Simulations of M87*-like Accretion Flows

Songyan Dai and Renyue Cen

Ideal-GRMHD calculations provide the bulk accretion flows used in black-hole emission models. A localized dissipation prescription can add a resolved map of current-sheet activity while retaining that dynamical reference. We implement such a prescription in Athena++, using a smooth threshold on the dimensionless current proxy $\alpha_J$ to select the magnetic-diffusion coefficient. The constrained-transport update is coupled to a conservative energy-flux correction. Gas heating follows from primitive recovery; $q_{Ohm}=\eta J^2$ is recorded as a diagnostic, without a second energy source. Static Fourier and traveling Alfvén tests measure the evolved thermal gain, and an open-boundary Schwarzschild test closes the Killing-energy ledger. The relative total-energy residual is below $2\times10^{-15}$ in these tests. A two-resolution Harris matrix gives localized rate exponents $0.510\pm0.027$ and $0.488\pm0.028$, consistent with $1/2$ over the specified early interval. The $\eta=10^{-3}$ rate exceeds the same-resolution ideal control by a factor of 5.96. In matched axisymmetric M87*-like runs, localized diffusion changes the early mean magnetic flux, accretion rate, and normalized flux by less than $0.02\%$, with a radial-density distance of $0.005\%$. During the late active phase, a common-restart on/off comparison keeps these mean shifts below $1.6\%$, within the intrinsic temporal variability, and gives a density distance of $0.29\%$. Uniform diffusion at the tested coefficient reduces the raw flux and accretion rate by $85\%$ and $99.8\%$. These comparisons establish a spatially selective diffusion prescription with explicit energy accounting and a quantified, small bulk-flow response.
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Astrophysics of Galaxies · Cross-listed from astro-ph.EP

High water D/H ratio of the interstellar object 3I/ATLAS is consistent with a low-metallicity origin

Kenji Furuya, Martin Cordiner, Dominique Bockelée-Morvan et al. (+5 more)

Recent JWST observations have revealed unusually high $^{12}$C/$^{13}$C ratios in carbon-bearing molecules of the interstellar object 3I/ATLAS, consistent with formation in a lower-metallicity environment than the present-day local interstellar medium (ISM). 3I/ATLAS also exhibits an exceptionally high water D/H ratio, exceeding those in Solar System comets and nearby low-mass star-forming regions. Here we investigate whether this high water D/H ratio can be reproduced in a low-metallicity formation scenario, using gas-ice astrochemical models. Assuming that the water observed in 3I/ATLAS was inherited from the parent molecular cloud and core, we perform a grid of astrochemical models covering the cloud to core stages, varying the gas density, ultraviolet radiation field ($\chi$), cosmic-ray ionization rate ($\zeta$), and metallicity, while solving thermal balance for the gas temperature. We find that lower metallicity enhances H$_3^+$ deuteration and, more importantly, its transfer to water ice. In contrast, water D/H ratio depends non-monotonically on $\chi$ and $\zeta$, because of competing chemical and thermal effects. In our models, the observed water D/H ratio is most readily reproduced at subsolar metallicities, $\lesssim0.5Z_\odot$, and relatively high cloud densities of $\sim$10$^4$ cm$^{-3}$ without strong constraints on either $\chi$ or $\zeta$, as long as $\zeta<10^{-15}$ s$^{-1}$. The D/H ratio of methane normalized by that of water is not sensitive to the metallicity, being consistent with the similar values observed in 67P/Churyumov-Gerasimenko and 3I/ATLAS. These results suggest that water deuteration may provide a complementary probe of the metallicity and physical condition of the parent molecular cloud and dense core of interstellar objects.
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All authors Kenji Furuya, Martin Cordiner, Dominique Bockelée-Morvan, Dennis Bodewits, Colin Orion Chandler, Maria N. Drozdovskaya, Nathan X. Roth, Geronimo Villanueva

Astrophysics of Galaxies

Stellar bar occurrence in TNG50 and TNG100: disentangling environmental effects and assembly history at z = 0

Karol Chim-Ramirez, Bernardo Cervantes-Sodi and Yetli Rosas-Guevara

In this work, we investigate the dependence of bar presence on environment using TNG50 and TNG100 simulations at z=0. We select disc galaxies within $2 R_{200}$, with stellar mass M$_{\star} \geq 10^{10}$ M$_{\odot}$ (TNG100) and M$_{\star} \geq 10^{9}$ M$_{\odot}$ (TNG50). With these criteria, our final samples consist of 1719 and 859 satellite galaxies in TNG100 and TNG50, respectively. The environment is characterised by host halo mass: massive (M$_{\rm h} \geq 10^{14}$ M$_{\odot}$), intermediate ($10^{13} < \rm M_{\rm h} < 10^{14}$ M$_{\odot}$), and low-mass haloes (M$_{\rm h} \leq 10^{13}$ M$_{\odot}$). We find that our samples recover the morphology-density relation, with thin disc fractions increasing with cluster-centric distance and decreasing halo mass. The bar fraction and the bar length normalized by the effective radius decrease mildly with cluster-centric distance, while absolute bar lengths remain constant. At fixed distance, the bar fraction increases with halo mass, partly because more massive galaxies reside in more massive haloes. In addition, we find that galaxies with earlier assembly times show a higher bar fraction, especially within $0.5 R_{200}$, suggesting a connection between earlier assembly and a higher probability of hosting a bar. Overall, we find a mild environmental dependence, with a stronger connection to stellar mass and assembly history.
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Astrophysics of Galaxies

Mapping the Quasar Main Sequence in the UV range: A Connection with the UV Fe III Emission

D. Martínez Collipal, M. L. Martínez-Aldama, A. Pandey et al. (+3 more)

The quasar main sequence (MS) provides a consistent unification scheme for type I AGNs. This framework, constructed from the relative flux between the optical emissions $\mathrm{H}\beta$ and $\mathrm{Fe\,II\,(\lambda4570)}$, and the $\mathrm{FWHM(H\beta)}$, organizes quasars into two populations (B, A) and the subpopulation xA, which typically consists of highly accreting sources. We explored the use of the UV 1900 blend emissions ($\mathrm{Al\,III}\,\mathrm{\lambda}1860$, $\mathrm{Si\,III]}\,\mathrm{\lambda}1892$, $\mathrm{C\,III]}\,\mathrm{\lambda}1909$) and the $\mathrm{Fe\,III}$ and $\mathrm{Fe\,II}$ transitions between 1700 and 2200 Angstrom as tracers of this main sequence. We fitted these emissions for a sample of 69 low-$z$ ($z\lesssim0.8$) quasars observed with the Hubble Space Telescope (HST) that had available optical measurements, enabling a direct comparison with the optical quasar main sequence. We found a UV plane defined by $\mathrm{FWHM}(\mathrm{Al\,III})$ and the equivalent width of the combined emissions of $\mathrm{Fe\,III}$ and $\mathrm{Fe\,II}$. The plane defined by these parameters mirrors the quasar main sequence in the optical regime and shows a clear distinction between the different populations. The plane also enables the identification of xA sources with high completeness but a non-negligible rate of false positives. Our results suggest that the UV iron emission around the 1900 blend could be used to trace the quasar main sequence trend, offering an alternative way to study this scheme at high redshift.
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All authors D. Martínez Collipal, M. L. Martínez-Aldama, A. Pandey, M. Cardenas, P. Marziani, S. Panda

Thursday 10 September

Astrophysics of Galaxies

NOEMA probes the [CII] and dust content in a 2175Å UV Bump Galaxy at $z=7.1$

Katherine Ormerod, Renske Smit, Joris Witstok et al. (+5 more)

The detection of the $2175$Å UV bump at $z>6$ challenges existing models of dust formation, suggesting rapid formation of small carbonaceous dust grains within the first billion years of cosmic time. We present the results of the first direct attempt at linking far-infrared (FIR) observations to the UV bump within the Epoch of Reionisation (EoR), through NOEMA observations of GNWY-7379420231 at $z=7.108$, a galaxy exhibiting the strongest known UV bump feature at $z>4$. We detect the [CII] 158$\mu$m emission line at 5.1$\sigma$ at $z_\mathrm{[CII]} = 7.1078 \pm 0.0005$, in excellent agreement with the redshift derived from the [OIII] $\lambda 5007$Å line. The {\cii} luminosity implies $\mathrm{SFR}_\mathrm{[CII]}=16.2^{+5.8}_{-5.5}M_\odot \mathrm{yr}^{-1}$, consistent with short timescale SFR tracers such as dust corrected $\mathrm{SFR}_\mathrm{H\alpha}=18.0\pm3.9 M_\odot \mathrm{yr}^{-1}$ and $\mathrm{SFR}_\mathrm{10~Myr}=20.5^{+3.8}_{-5.0}M_\odot \mathrm{yr}^{-1}$ from SED fitting. The dust continuum is not detected suggesting an obscured SFR of $\mathrm{SFR}_\mathrm{IR} < 32 ~M_\odot \mathrm{yr}^{-1}$ and a dust mass of $M_\mathrm{d} < 5.3\times10^6 ~M_\odot$ $(M_\mathrm{d}/M_\star<2\%)$. Finally, the [CII]-derived dynamical mass of $\log_{10}(M_\mathrm{dyn}/M_\odot)=8.95^{+0.51}_{-0.66}$ and stellar mass of $\log _{10}\left(\mathrm{M}_{\star} / \mathrm{M}_{\odot}\right) = 8.39_{-0.09}^{+0.13}$ suggest a gas-rich moderately massive galaxy. Taken together these results rule out GNWY-7379420231 being a heavily dust obscured or massive galaxy, but rather a `normal' EoR galaxy with a recent upturn in star-formation. Our results suggest efficient shattering of larger dust grains in the diffuse, turbulent ISM and/or fortunate line of sight alignment are needed to explain the UV bump properties of GNWY-7379420231.
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All authors Katherine Ormerod, Renske Smit, Joris Witstok, Anna de Graaff, Michael V. Maseda, Irene Shivaei, Andrew J. Bunker, Gareth C. Jones

Astrophysics of Galaxies

Unified modelling of broad and narrow optical-UV emission lines from massive black holes: interpreting high-redshift JWST observations

Adele Plat, Michaela Hirschmann, Emma Curtis-Lake et al. (+10 more)

JWST is uncovering a large population of active galactic nuclei (AGN) at high redshift, motivating the extension of models calibrated on local sources to a broader range of physical conditions. We present a consistent suite of broad- and narrow-line photoionisation models based on ionising spectra that vary with black-hole mass and Eddington ratio, spanning sub- to super-Eddington accretion. For the broad-line region (BLR), we investigate the detectability of low-mass accreting black holes. At z=6, broad H{\alpha} may be detectable down to $M_{BH}\approx10^{5.7} M\odot$ for a BH accreting at the Eddington limit under favourable assumptions. We derive line-to-accretion-luminosity corrections, with hydrogen and helium recombination lines providing more robust tracers than metal lines. We also explore which changes in black-hole properties and BLR conditions can contribute to the large H{\alpha} equivalent widths, elevated Balmer decrements, and weak high-ionisation lines observed in some high-redshift sources, finding that variations in BLR structure can substantially modify the emergent spectrum. For the narrow-line region (NLR), H{\alpha} and [O III] {\lambda}5007 are among the most promising tracers of low-mass accreting black holes, probing $M_{BH}\approx10^{5.5} M\odot$ at the Eddington limit. Many classical diagnostic diagrams miss low-metallicity AGN; we identify alternative UV and optical diagnostics that more robustly separate AGN from Pop. II and Pop. III stellar photoionisation over the conditions explored. Nevertheless, NLR line ratios are driven primarily by metallicity and ionisation parameter, with only a weak dependence on black-hole mass and Eddington ratio. Looking ahead, these models are intended for Bayesian interpretation of JWST spectra and connection to cosmological simulations through physically motivated priors.
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All authors Adele Plat, Michaela Hirschmann, Emma Curtis-Lake, Anna Feltre, Stephane Charlot, Steven L. Finkelstein, Lorenzo Napolitano, Fabio Pacucci, Norbert Pirzkal, Sandra Raimundo, Anthony Taylor, Alba Vidal-Garcia, L. Y. Aaron Yung

Astrophysics of Galaxies

BAQARO: Tracing Stochastic Black Hole Growth Histories and Quasar Lightcurves in a Cosmological Context

Elia Pizzati, Joseph F. Hennawi and Joop Schaye

How supermassive black holes (BHs) assemble their mass and power the luminous quasars we observe across cosmic time remain central open questions in galaxy evolution. We present BAQARO, a semi-empirical framework for BH growth. Built on subhalo merger trees extracted from the FLAMINGO-10k simulation, the model links BH growth histories to those of their host subhalos through prescriptions that capture both average trends and stochastic variability. BAQARO is constrained by the bolometric quasar luminosity function, the clustering of UV-luminous quasars, and the conditional Eddington ratio distribution function. With six free parameters controlling BH seeding, the coupling between gas accretion and halo growth, and the stochasticity and temporal coherence of accretion, the model reproduces the available observational constraints over $0 \lesssim z \lesssim 7$. Using emulators, we perform Bayesian inference and quantify the constraining power of each observable. Our main findings are: (i) BH accretion is well described by the assembly of cold gas reservoirs in halos, without requiring an explicit dependence on cosmic time. (ii) BHs rapidly assemble their mass at high redshift through stochastic episodes of super-Eddington accretion. (iii) These episodes are radiatively inefficient and persist for timescales of $\sim1\,\mathrm{Myr}$, imprinting observable signatures on quasar lightcurves, proximity zones, and clustering measurements. (iv) The merger growth channel is always subdominant, but becomes increasingly important at $z \lesssim 1$, particularly for massive BHs. BAQARO growth histories and quasar lightcurves provide a flexible framework for interpreting the rapidly expanding landscape of quasar observations, from high-$z$ accretion probed by JWST to low-$z$ mergers constrained by pulsar timing arrays.
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Astrophysics of Galaxies

Galaxies in the first two billion years: Earlier formation and quenching with surface-density modulated star formation and feedback

Akash Vani, Mohammadreza Ayromlou, Guinevere Kauffmann et al. (+1 more)

JWST has revealed massive, UV-bright, compact, and in some cases quenched galaxies in the first two billion years of cosmic history, challenging current galaxy formation models. We develop an extended L-Galaxies semi-analytic model, run on the MillenniumTNG dark-matter-only simulation, and follow galaxy evolution over $0 \le z \lesssim 15$. The model ties the star formation efficiency and the coupling of stellar feedback energy to the local cold gas surface density, making star formation efficient and feedback ineffective in dense gas. We include dissipative gas-rich mergers and disc instabilities in stellar and gaseous discs. All parameters are calibrated simultaneously against stellar mass functions and quenched fractions at $z\simeq0-4$ and UV luminosity functions at $z\simeq11-12$ with a new parallelised Markov chain Monte Carlo framework. The model reproduces the stellar mass function up to $z\approx 11$ and increases the abundance of massive and UV-bright galaxies at $z\gtrsim9$ by up to two orders of magnitude over the legacy version. Although the AGN feedback prescription is unchanged, the enhanced bulge growth and black hole fuelling make massive quenched galaxies at $z\simeq3-8$ two orders of magnitude more abundant, while dissipative mergers produce compact remnants with UV size-luminosity relations matching observations at $z\simeq10-13$. At low redshift, galaxy sizes, cold-gas content, metallicities, radial profiles, and morphologies remain consistent with observations. Our results indicate that the tension between models and JWST observations at cosmic dawn can be substantially reduced by regulating star formation and feedback through the local gas surface density, without a modified initial mass function, non-standard cosmology, or new AGN physics.
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All authors Akash Vani, Mohammadreza Ayromlou, Guinevere Kauffmann, Volker Springel

Astrophysics of Galaxies

Resolved SED modelling with JWST and ALMA: the role of stellar mass surface density in regulating star formation in cosmic noon galaxies

Cheng-Lin Liao, Leindert A. Boogaard, Jacqueline A. Hodge et al. (+27 more)

We present kpc-scale ($0.2''-0.5''$) physical property maps of 35 main-sequence galaxies at $z \approx 0.5-3.7$, with stellar masses of $\log(M_*/M_\odot) \sim 9.7-11.7$ and star formation rates of $\mathrm{SFR} \sim 1.4-280\,\mathrm{M_\odot\,yr^{-1}}$, selected from the ALMA Spectroscopic Survey (ASPECS) in the Hubble Ultra Deep Field. Leveraging the unique HST, JWST (NIRCam and MIRI), and ALMA observations, we perform spatially resolved spectral energy distribution (SED) modeling across the UV-to-FIR regime. We find that incorporating MIRI and/or ALMA data reduces the overestimation of dust luminosity (by up to $\sim0.8$ dex), while ALMA observations further mitigate the age-dust degeneracy. In the absence of such data, restricting the SED model library based on the observed unresolved colors can partially mitigate these biases. The stellar masses ($M_{*}$) derived from resolved and unresolved modeling are consistent within $\sim0.05$ dex, suggesting that mass discrepancies (attributed to outshining) are less significant for cosmic noon main-sequence galaxies when rest-frame near-infrared (NIR; e.g., $\sim1-3\,\mu\mathrm{m}$) data are included. After normalization to the same reference, the composite SED of our sample closely resembles that of local starburst galaxies such as M82, suggesting similar dust attenuation and re-emission properties. Finally, we find that the molecular gas fraction and depletion time correlate with the effective stellar mass surface density ($\Sigma_{\rm eff,*} = M_{*}/2\pi R_{\rm eff,M_*}^2$) similarly to that observed in local galaxies. These results provide a first qualitative view of how the stellar gravitational potential influences gas regulation and star formation in galaxies beyond the local Universe.
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All authors Cheng-Lin Liao, Leindert A. Boogaard, Jacqueline A. Hodge, J. Li, E. da Cunha, P. Sharda, A. Battisti, C. Lagos, M. Kaasinen, I. Smail, M. Aravena, F. E. Bauer, R. K. Cochrane, L. Colina, P. Cox, R. Decarli, T. Díaz-Santos, R. Fernández Aranda, N. N. Geesink, H. Inami, B. Magnelli, J. Melinder, M. Neeleman, G. Östlin, G. Popping, D. A. Riechers, I. Shivaei, P. van der Werf, F. Walter, A. Weiss

Astrophysics of Galaxies

Little Red Dots are Direct-Collapse Black Hole-Forming Galaxies

Daniel J. Whalen, Muhammad A. Latif, Konstantinos Topalakis et al. (+3 more)

"Little Red Dots" (LRDs) at $4 < z < 8$ are one of the most challenging discoveries by JWST to date because their distinctive V-shaped spectra and compact morphologies (100 - 200 pc) defy conventional astrophysical interpretation. Previous attempts to explain LRDs as compact stellar systems, heavily-cocooned black holes with differential flows, supermassive stars, or more exotic objects like 'black-hole stars' either cannot show how they formed, explain the origin of the dense shells needed for the absorption features in their spectra, or account for their observed abundances or inferred lifetimes. Here we show that LRDs are simply direct-collapse black hole galaxies in which the BH is still shrouded by the massive disk that created it. Our cosmological simulations yield spectra that are good matches to those of LRDs because high densities at the center of the disk trap X-rays from the BH and produce the observed Balmer absorption features while allowing UV, optical and reprocessed IR flux to partly escape. The host galaxy forms a dense 10$^8$ M$_{\odot}$ cluster of stars with a radius of 150 pc next to the BH, consistent with observations of LRDs. Our models reproduce a wide variety of LRD spectra from typical objects like RUBIES-EGS-42046 at $z = 5.28$ to those with the strongest Balmer breaks such as MoM-BH$^*$-1 at $z = 7.76$ and those at the highest redshifts like CAPERS-LRD-z9 at $z = 9.29$.
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All authors Daniel J. Whalen, Muhammad A. Latif, Konstantinos Topalakis, Fergus Cullen, Devesh Nandal, Sadegh Khochfar

Astrophysics of Galaxies

Clustering-based halo mass assignment for high-redshift galaxies: method, validation, and application to JWST

Seunghwan Lim, Sandro Tacchella, Sara Saleh et al. (+7 more)

We present a clustering-based method for inferring halo masses of high-redshift galaxies, validated using the COLIBRE simulations combined with the HOMA empirical model, which assumes star formation to be proportional to halo accretion rate and is calibrated to JWST observations. Our approach matches the two-point correlation function of galaxies in stellar mass bins to reference halo clustering, establishing the stellar-to-halo mass relation over an optimal radial range 0.5 < r_p/cMpc < 1.0. Validation against true halo masses shows minimal bias, with scatter below 0.3 dex for volumes down to (50 cMpc)^3 and redshifts to z=12, even for photometric data. Cross-validation using the native COLIBRE population shows that the method is robust to the different galaxy-halo prescriptions. Survey volume dominates the error budget: field-to-field variations in the clustering amplitude vary by factors of 3 (2) for photometric (spectroscopic) samples, translating to 0.3-0.5 dex uncertainty in halo masses. Splitting the sample by properties such as SFR, colour, and age mitigates assembly bias, offering a key advantage over abundance matching. Application to JWST (JADES) samples at z=6 and 10 yields halo masses of log M_h/M_sun = 10.52_{-0.21}^{+0.12} and 9.91_{-0.34}^{+0.19} for M_UV < -17 galaxies, with linear biases of b_h = 4.2_{-0.41}^{+0.26} and 7.7_{-1.16}^{+0.77}, respectively. Current data cannot distinguish between star formation models. Our Roman Deep Tier forecasts indicate that at z=10, the inferred halo masses for M_UV < -21 galaxies differ by 0.5 dex between bursty and non-bursty models, but the expected number of pairs limits the constraining power. Our framework provides robust, empirically-calibrated halo masses essential for interpreting JWST observations and constraining galaxy formation during reionization.
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All authors Seunghwan Lim, Sandro Tacchella, Sara Saleh, Roberto Maiolino, Lily Whitler, Joop Schaye, Evgenii Chaikin, Carlos S. Frenk, Filip Huško, Alexander J. Richings

Astrophysics of Galaxies

Learning JWST. I. A Foundation Model for New Population Discoveries and Morphology-Aware Photometric Redshift Measurements in the JADES Survey

Jiani Ding, Minghao Yue, Yongda Zhu et al. (+2 more)

We present FM-JADES-v1, a self-supervised foundation model for James Webb Space Telescope (JWST) deep-field science, trained with 482,444 objects from the JWST Advanced Deep Extragalactic Survey (JADES) Data Release 5 using multi-band imaging and the photometric catalog. The shared embedding space is trained without class labels. We demonstrate that FM-JADES-v1 can serve as a powerful tool for object discovery and improving property measurements using two experiments, blind active discovery and few-band photometric redshift. For blind object discovery, FM-JADES-v1 identifies rare object populations such as high-redshift galaxies and Little Red Dots (LRDs) without any prior population labels or population-specific selection criteria. These rare populations emerge as isolated islands in the embedding space, which can be identified without prior astrophysical knowledge. For few-band photometric redshift, FM-JADES-v1's learned embeddings achieve $\sigma_{\rm NMAD}=0.157$ in a strictly controlled three-band (F115W/F200W/F356W) photo-$z$ benchmark, compared to $\sigma_{\rm NMAD}= 0.44$ for template fitting. These results demonstrate the potential of self-supervised multi-modal representations as scalable discovery spaces for large astronomical surveys. Applied to ongoing and future wide-field surveys from JWST, Roman, Euclid, and Rubin/LSST, this framework could enable systematic searches for rare populations, as well as enabling multiple downstream tasks such as improving astrophysical property measurements.
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All authors Jiani Ding, Minghao Yue, Yongda Zhu, Xiaohui Fan, Yufeng Luo

Astrophysics of Galaxies · Cross-listed from astro-ph.SR

A Homogenized Catalogue of Variable Stars in the Globular Cluster M22: Membership, Physical Parameters, and Distance

M. A. Yepez, B. Moreno-Amaro, M. Ornelas-Castañeda et al. (+2 more)

We present a photometric analysis of the variable stars in the field of the globular cluster M22 (NGC 6656), using time-series photometry from the literature and from OGLE and Gaia-DR3 data. From a sample of 666 variable stars in the field, we identify 94 as cluster members, including 10 RRab, 17 RRc, 2 Type II Cepheids, 15 SX Phe, 15 SR stars and 22 eclipsing binaries. Fourteen of these members are not included in the Catalogue of Variable Stars in Globular Clusters. Through the Fourier decomposition of the RR Lyrae light curves, we derived $[\mathrm{Fe/H}] = -1.73 \pm 0.17$ dex and $d = 3.27 \pm 0.14$ kpc. Among the RRc stars, V15 shows an additional frequency with a frequency ratio $f_{0.61}/f_\mathrm{1O} = 0.6152$, consistent with the RR$_{0.61}$ phenomenon. Using P-L relations for member SX Phe stars, we obtained $d = 3.31 \pm 0.17$ kpc, consistent with the RR Lyrae distance. We constructed a CMD comprising only cluster members, which allows us to confirm the evolutionary status of the cluster's RR Lyrae stars. None of the fitted isochrones satisfactorily reproduces the CMD morphology, which is consistent with the presence of multiple stellar populations in M22.
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All authors M. A. Yepez, B. Moreno-Amaro, M. Ornelas-Castañeda, A. Arellano Ferro, D. Deras

Astrophysics of Galaxies

The atomic multiphase interstellar medium of galaxies in the COLIBRE simulations

Moa Huppenkothen, Sylvia Ploeckinger, Joop Schaye et al. (+7 more)

We analyse the neutral ISM of galaxies at redshift z=0 in the COLIBRE hydrodynamical simulations and investigate the conditions under which these two gas phases coexist in a narrow range of thermal pressures. COLIBRE galaxies are selected based on the metallicity of their ISM. The median and mass-weighted distributions of thermal pressures of the multiphase ISM are analysed and compared to thermal equilibrium models and observations. The ISM in galaxies with gas metallicities similar to solar values exhibits a clear multiphase structure with a warm and cold phase coexisting in a certain range of thermal pressures. The pressures at which the ISM is multiphase depend on the gas metallicity. For COLIBRE galaxies with lower metallicities ($Z_{\mathrm{ISM}}\lesssim0.1\,\mathrm{Z}_{\odot}$), this multiphase structure largely disappears, partly due to resolution. The thermal pressures weighted by the HI mass of the neutral phases in COLIBRE galaxies are lower than, but still comparable to, some theoretical works and observational estimates. The thermal pressures show a strong dependence on the weighting scheme. If weighted by the star formation rate or CI mass, the thermal pressures of the cold phase match those derived from observations. The resulting pressures depend on a combination of the assumed radiation field strength, dust abundance, limited resolution and the weighting scheme. The strong dependence of the thermal pressures on the weighting scheme indicates observational tracers used to estimate the thermal pressure are biased towards high-pressure regions.
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All authors Moa Huppenkothen, Sylvia Ploeckinger, Joop Schaye, Alejandro Benítez-Llambay, Evgenii Chaikin, Filip Huško, Alexander J. Richings, James W. Trayford, Alvaro Hacar, Juan D. Soler

Astrophysics of Galaxies

Testing Chemical Tagging with LAMOST: Intrinsic Abundance Dispersion of Subgiant Stars in the Galactic Disk

Wu Yaqian, Xiang Maosheng, Zhao Gang et al. (+4 more)

The scatter in elemental abundances among stars of similar age and metallicity reflects chemical inhomogeneity in their birth environments, making abundance scatter a key observable for chemical-tagging studies of Galactic formation and evolution. Using a large sample of subgiant stars with precise ages and elemental abundances derived from LAMOST low-resolution spectra, we investigate the intrinsic chemical abundance scatter of the low-$\alpha$ thin disk near the solar neighborhood ($7 < R < 10$ kpc). We model the abundance ratio [X/Fe], for each of the 19 elements of concern, as a function of age, [Fe/H], and [Mg/Fe], and deduce the intrinsic dispersions with a forward modelling technique. Our results confirm previous findings that the intrinsic scatters are small, typically $\lesssim0.05$~dex, for light elements (C, Al), $\alpha$-elements (O, Mg, Si, Ca, Ti), and iron-peak elements (Mn, Ni). A dedicated analysis of M67 yields similarly small scatter values for these elements, implying limited discriminatory power from light-element abundances alone. In contrast, neutron-capture elements exhibit substantially larger scatters, typically $\gtrsim$0.1 dex, which are significantly larger than those of M67 member stars ($\sim$0.07~dex). In particular, our analysis suggests that the abundance variations of individual neutron-capture elements cannot be explained by a single tracer such as [Ba/Fe]. These findings clarify the utility of neutron-capture elements for chemical tagging and highlight the potential of low-resolution spectroscopy in such studies.
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All authors Wu Yaqian, Xiang Maosheng, Zhao Gang, Jiang Ruizheng, Li Zhuohan, Bi Shaolan, Zhang Meng

Astrophysics of Galaxies

Generating the wide sequence of Diffuse Galaxies with de Broglie waves of Dark Matter

Jiashuo Zhang, Tom Broadhurst, Alvaro Pozo et al. (+9 more)

Extensive Euclid satellite imaging at low surface brightness has revealed that most nearby galaxies are diffuse-looking spheroids, where the stellar radius increases for over three decades in luminosity. We argue this Diffuse Galaxy sequence results from internal stellar diffusion by Wave Dark Matter ($\psi$DM), as wave energy is transferred to star orbits over time. In particular, the soliton random motion scatters central stars onto radial orbits that become enhanced with each passage through the centre, slowly “puffing up" the stellar profile. Heating is greater within massive galaxies as $\psi$DM fluctuations are stronger and more frequent, reproducing both the Diffuse Galaxy sequence and the rising velocity dispersion along the sequence, from Ultra-Faint to Dwarf Spheroidal and Ultra Diffuse galaxies, favouring a light boson, $m_\psi=2.88^{+0.14}_{-0.13}\times10^{-22}$eV. Winding back this diffusion, we predict the stellar content of Diffuse Galaxies, including globular clusters, formed near the centre, as anticipated by $\psi$DM simulations, where gas cools efficiently within the dense soliton. This predicted $\psi$DM evolution from compact beginnings towards diffuse spheroidal galaxies today can now be fully charted from JWST to Euclid.
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All authors Jiashuo Zhang, Tom Broadhurst, Alvaro Pozo, Tzihong Chiueh, Justin Schive, Bo-Ren You, Jeremy Lim, Francine Marleau, Tomomi Sunayama, Keiichi Umetsu, Mariam Bouhmadi-Lopez, Masamune Oguri

Astrophysics of Galaxies

Resonantly Scattered CIV Emission in Local Star-forming Galaxies: Radiative Transfer Constraints on High-ionization Gas in Reionization Analogs

Zhihui Li, Danielle A. Berg, Simon Gazagnes et al. (+4 more)

Rest-frame ultraviolet emission lines are diagnostics of hard ionizing spectra and highly ionized gas in galaxies resembling the sources of cosmic reionization. Nebular CIV emission traces both intrinsic line production and resonant scattering through its velocity-resolved profile. Previous studies have treated CIV empirically, using integrated fluxes, equivalent widths, and line ratios rather than modeling the radiative transfer (RT) shaping the emergent profiles. We present the first systematic RT modeling of resonantly scattered CIV emission profiles in 18 local star-forming galaxies observed with HST/COS. Using the clumpy RT framework PEACOCK, idealized experiments show that profile morphology is governed by column density, gas kinematics, intrinsic equivalent width, and aperture-dependent recovery of scattered emission. We fit continuum-normalized spectra corrected for stellar contributions with a neural-network-accelerated Bayesian pipeline, reproducing P-Cygni-like, double-peaked, double-peaked with two absorption troughs, and blue-bump plus red-peak morphologies. Emission infilling connects these profile classes and complicates kinematic inferences, while aperture losses decouple observed net equivalent widths from intrinsic line production. Combining RT-inferred intrinsic equivalent widths with rest-UV diagnostics, we find that most galaxies are consistent with stellar photoionization, although some may require harder spectra or more extreme ionization conditions. Comparison with CLASSY reveals stronger associations of stellar mass and star formation rate with gas kinematics than with CIV column density. Our results establish CIV as both a tracer of hard ionizing radiation and a resonant-line probe of gas structure and kinematics, with velocity-resolved profiles providing information beyond integrated line strengths in local reionization analogs.
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All authors Zhihui Li, Danielle A. Berg, Simon Gazagnes, Timothy Heckman, Max Gronke, Dawn K. Erb, John Chisholm

Astrophysics of Galaxies

Tracing Warm Gas through C IV Radiative Transfer

Jin Lim, Seok-Jun Chang, Max Gronke et al. (+3 more)

The C IV $\lambda\lambda1548,1551$ resonance doublet is a key tracer of warm gas ($T\sim10^5\,{\rm K}$) within and around galaxies. Recent observations have detected this line in both absorption and emission, revealing asymmetric profiles in galaxies and spatially extended haloes around active galactic nuclei (AGNs). Resonance scattering can strongly modify the emergent spectra and spatial distributions, complicating their interpretation. Using 3D Monte Carlo radiative transfer simulations, we study C IV resonance scattering over a broad range of column densities, intrinsic emission-line widths, and outflow velocities. We find that multiple scattering broadens the line profile and, in outflowing media, modifies the doublet ratio, $R_{\rm CIV}$, defined as the flux ratio of the K and H components at 1548 and 1551 $\mathrm{\mathring{A}}$, respectively. When the outflow velocity approaches or exceeds the doublet separation ($\simeq500\,{\rm km\,s^{-1}}$), K-line photons are redistributed around the H component, driving $R_{\rm CIV}$ below its intrinsic value and, in optically thick fast outflows, even below unity. We also combine photoionization models with resonance scattering to investigate extended C IV haloes around AGNs and compare them with He II $\lambda1640$ emission. Simple photoionization models do not produce C IV emission more extended than He II, whereas resonance scattering redistributes locally produced and central-source C IV photons to larger radii. These results demonstrate that the C IV doublet ratio and spatial distribution provide complementary diagnostics of warm gas.
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All authors Jin Lim, Seok-Jun Chang, Max Gronke, Fabrizio Arrigoni Battaia, Hee-Won Lee, Kwang-Il Seon

Astrophysics of Galaxies

The properties of central stellar knots embedded in galactic bulges of CIELO simulations

Belén Acosta-Tripailao, Patricia B. Tissera, Manuela Zoccali et al. (+7 more)

Deeply bound stellar substructures of about 1 kpc at the center of bulges are found in a subset of galaxies from the cosmological chemo-hydrodynamical zoom-in CIELO simulation suite. They were identified as stellar overdensities at the lowest binding energies in each galaxy's circularity-energy $(\epsilon, E)$ plane. We refer to these overdensities as stellar knots. We aim to characterize their properties in the context of bulge assembly using CIELO simulated galaxies spanning a wide range of stellar masses ($10^{8.0}$-$10^{10.7}\,\mathrm{M}_{\odot}$), with diverse formation histories. We inspect 54 galactic bulges. Within them, we isolate stellar knot candidates in $(\epsilon, E)$ space, and identify 28 robust knots satisfying successive selection criteria: kinematic, concentration, and morphology. We characterize their chemical enrichment, formation timescales, formation sites, progenitor gas origin, and spatial distributions. Across all galaxy masses, knots are systematically alpha-element enhanced, having assembled the bulk of their stellar mass at earlier epochs and on shorter timescales than other bulge populations, with a median of $\sim$2$\,$Gyr versus $\sim$5$\,$Gyr. Regarding their origin, knots are predominantly in-situ ($5\%$ accreted mass fraction, roughly half that of the rest of the bulge), with negligible disk-born stars contribution and the largest gas fractions originating from a primordial central spheroid ($21\%$ versus 16–17$\%$ for the surrounding populations), consistent with being the primary gas fuel for the alpha-element enhancement. In terms of structure, knots exhibit a variety of morphologies, with spheroidal shapes predominating. Dynamical selection in $(\epsilon, E)$ space of CIELO galaxies demonstrates its effectiveness in recovering coeval stellar populations, pointing to stellar knots as plausible fossil signatures of early in-situ bulge assembly.
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All authors Belén Acosta-Tripailao, Patricia B. Tissera, Manuela Zoccali, Jenny Gonzalez-Jara, Brian Tapia-Contreras, Ignacio Muñoz-Escobar, Susana Pedrosa, Nelson D. Padilla, Lucas Bignone, Rosa Dominguez-Tenreiro

Astrophysics of Galaxies

Constraints on the fuzzy dark matter mass using globular clusters in dwarf galaxies from Euclid ERO data

Lisa Besnard, Pierre Boldrini, Paola Di Matteo et al. (+2 more)

We constrain the particle mass of the fuzzy dark matter model using globular cluster candidates in dwarf galaxies, from the Euclid Early Release Observations, within the Fornax and Perseus galaxy clusters. We model the orbital evolution of globular clusters by combining fuzzy dark matter density profiles with the corresponding dynamical friction formalism, and integrate their orbits using galpy. In the fuzzy dark matter framework, both the halo density profile and the dynamical friction force are modified by the wave-like nature of the ultra-light dark matter particle, whose mass is parameterized as $m_{22}=m_\chi/10^{-22},\mathrm{eV}$ and explored over the range $0.1 \leq m_{22} \leq 100$. This framework naturally alleviates the long-standing globular cluster timing problem originally identified in the Fornax dSph. We find that globular clusters no longer experience orbital decay toward the centers of their host galaxies for $m_{22}\leq1.46^{+0.51}_{-0.32}$ in the Fornax cluster and $m_{22}\leq1.09^{+0.14}_{-0.21}$ in the Perseus cluster. Future Euclid data releases, providing substantially larger samples of globular cluster candidates, will enable significantly tighter constraints on the dark matter particle mass within the fuzzy dark matter scenario.
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All authors Lisa Besnard, Pierre Boldrini, Paola Di Matteo, Chervin Laporte, Teymoor Saifollahi

Astrophysics of Galaxies

No Detectable One-halo Galactic Conformity Signal with Halo-mass Estimates Consistent with Weak-lensing Constraints

Dingyi Zhao, Yingjie Peng, Luis C. Ho et al. (+17 more)

One-halo galactic conformity is the tendency for satellites in halos with quenched centrals to have lower star-formation activity than those in halos with star-forming centrals at fixed halo mass. It is an important probe of the galaxy–halo connection and halo-wide quenching processes that may couple central and satellite evolution. However, its existence remains controversial, because conformity must be measured at fixed halo mass, while halo masses are difficult to estimate accurately. In this Letter, we measure one-halo conformity in SDSS using five stellar-mass-complete samples and three halo-mass estimates: an ML estimate whose star-forming and quenched stellar mass–halo mass relations (SHMRs) agree with independent weak-lensing constraints, and two conventional abundance-matching (AM) estimates. We quantify conformity as the difference in median $\log({\rm sSFR})$ between satellites of star-forming and quenched centrals, using both satellite-level and halo-level statistics. The two AM estimates produce strong positive conformity signals, consistent with previous AM-based measurements, but these signals are not reproduced with the ML halo masses. For the halo-level statistic, the representative AM-based signals are $+0.38\pm0.04$ dex and $+0.23\pm0.04$ dex for the luminosity-ranking and mass-ranking AM halo masses, detected relative to no conformity at about $10\sigma$ and $6\sigma$, respectively. In contrast, the ML result is consistent with no conformity, $+0.00\pm0.03$ dex; the satellite-level statistic gives a similar result. Thus, with halo-mass estimates consistent with weak-lensing constraints, we find no detectable one-halo conformity signal in the present SDSS sample, suggesting that the strong AM-based signal is largely driven by halo-mass estimation biases.
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All authors Dingyi Zhao, Yingjie Peng, Luis C. Ho, Houjun Mo, Cheqiu Lyu, Kai Wang, Yijun Wang, Tao Wang, Jing Dou, Zeyu Gao, Qiusheng Gu, Yukun Liu, Roberto Maiolino, Alvio Renzini, Bitao Wang, Yu-Chen Wang, Bingxiao Xu, Feng Yuan, Kunyao Zhao, Xingye Zhu

Astrophysics of Galaxies

Black Hole-Galaxy Correlations in Cluster Zoomed-in Simulations: GIZMO-SIMBA and TNG-Cluster

Hangxin Pu, Antonios Katsianis, Weiguang Cui et al. (+8 more)

We investigate the co-evolution of supermassive black holes (SMBHs) and central galaxies in massive clusters using the GIZMO-SIMBA and TNG-Cluster zoom-in simulations at $z=0-5$. We find that the distinct subgrid physics of these two models suggest fundamentally different evolutionary pathways. On the one hand, GIZMO-SIMBA, employs torque-limited accretion and predicts a supply-driven scenario where the SMBHs rapidly assemble synchronized with dark matter halo ($M_{200c}$) growth (i.e. the halo mass-BH mass relation is set by $z=3.0$ and similar to the present-day relationship). On the other hand, TNG-Cluster, exhibits a feedback-regulated growth phase delayed by an early thermal suppression. While both models successfully reproduce some local black hole-galaxy scaling relations, they imply significantly different evolution for these relations. Analysis of the BH mass-gas mass ratio relations suggests that TNG-Cluster's isotropic kinetic winds efficiently deplete cold gas, resulting in a "hard quench" of star formation. In the black hole accretion rate (BHAR)-star formation rate (SFR) relation we find that both simulations successfully reproduce the decoupling of BHAR and star formation observed in recent massive cluster ellipticals. The divergent evolutionary trends emphasize the importance of the multiphase intracluster medium; while these subgrid models do not have the necessary resolution and employ distinct formalisms, the sustained BHAR in quenched systems resemble outcomes broadly consistent with modern multiphase feeding paradigms such as chaotic cold accretion in turbulent cluster cores. Furthermore, we demonstrate that for both models, black hole mass is a primary regulator of atomic and molecular gas depletion in galaxy clusters.
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All authors Hangxin Pu, Antonios Katsianis, Weiguang Cui, Romeel Davé, Massimo Gaspari, Weishan Zhu, Xiaohu Yang, Jinyi Shangguan, Qingshan Wang, Ying Tang, Yuchang Li

Astrophysics of Galaxies

Nitrogen-Loud Quasars from the Dark Energy Spectroscopic Instrument. I. Sample Selection and Basic Properties

Shuo Zhai, Wei-Jian Guo, Yong-Jie Chen et al. (+4 more)

We present the largest sample to date of nitrogen-loud (N-loud) quasars with strong broad N IV] $\lambda1486$ and/or N III] $\lambda1750$ emission lines over the redshift range $1.6 < z < 4.3$, selected from the Dark Energy Spectroscopic Instrument (DESI) Data Release 1. The final sample contains 1,993 N-loud quasars, corresponding to about 1.2% of the parent quasar sample. The $L_{1450}$ distribution of the N-loud quasars is broadly similar to that of the DESI parent sample, but their redshift distribution is distinct, with a stronger concentration around $z \sim 2.5$–3. Their composite spectrum displays a broadly similar UV continuum shape to that of the parent quasars, while showing significantly enhanced broad nitrogen emission features, including N V, N IV], and N III]. Other metal emission features also show a moderate enhancement. Relative to a control sample matched in redshift and UV continuum luminosity, the N-loud quasars show systematically narrower broad C IV and Mg II emission lines, lower single-epoch virial black hole masses, and higher Eddington ratios, suggesting that N-loud quasars may preferentially appear during a relatively rapid black hole accretion phase. The radio-loud fraction is 10.1%, with the highest fraction among objects exhibiting both N III] and N IV] emission. The catalog provides a statistical baseline for future studies of nitrogen enhancement and its physical origin.
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All authors Shuo Zhai, Wei-Jian Guo, Yong-Jie Chen, Zhi-Qiang Chen, Haining Li, Jian-Min Wang, Gang Zhao

Astrophysics of Galaxies

SPURS: An Ultra-deep View Inside the Compact, Nitrogen-Enriched Nuclei of Little Red Dots

Mengtao Tang, Daniel P. Stark, Charlotte A. Mason et al. (+7 more)

We present the first ultra-deep rest-UV spectroscopy of four UV-bright Little Red Dots (LRDs), obtained from the SPURS Cycle 4 Large Program. The spectra reveal broad CIV (FWHM $\approx2700-2800$ km s$^{-1}$) in two LRDs, alongside narrow-line densities elevated above star-forming galaxies ($n_e\sim10^4-10^5$ cm$^{-3}$, reaching $10^6$ cm$^{-3}$ in the most extreme source) and nitrogen-enhancements in all four LRDs. We detect broad HeII emission (FWHM $\approx930$ km s$^{-1}$) in one LRD, and two others with fast P-Cygni absorption ($\gtrsim2200$ km s$^{-1}$). Strong interstellar absorption lines and Ly$\alpha$ damping wings reveal the UV continuum is deeply embedded in neutral gas ($N_{\rm HI}\gtrsim10^{22}$ cm$^{-2}$) in all four LRDs. Detections of fluorescent FeII and OI emission and fine-structure absorption indicate this gas lies close to the UV-emitting region. In archival $z>4$ samples, we find nitrogen and strong CIII] emission are significantly more common in LRDs than in the galaxy population. The transmission of broad CIV, tracing the broad-line region or cocoon, depends on rest-optical color within our sample, consistent with an orientation-dependent picture in which bluer, less obscured sightlines offer a more direct, polar view of the central engine and its outflows. We find several potential signatures of very massive stars, whose winds may contribute to nitrogen enhancement. We investigate other abundance patterns expected from supermassive stars but our results are inconclusive. Our results place the UV-emitting region within $\lesssim8$ pc of the LRD nucleus, consistent with an actively assembling nuclear star cluster. Dynamical interactions in this extremely dense environment, including tidal disruption of stars, may explain the high incidence of nitrogen enhancements in LRDs.
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All authors Mengtao Tang, Daniel P. Stark, Charlotte A. Mason, Zuyi Chen, Tucker Jones, Sarah Searle Grannis, Peter Senchyna, Lily Whitler, Keerthi Vasan G. C., Viola Gelli