Astrophysics of Galaxies · Cross-listed from astro-ph.SR
Twisted Pseudodisk and Asymmetric Mass Accretion on the Circumstellar Disk II: Parameter Survey
Masahiro N. Machida, Shingo Hirano and Shantanu Basu
Using three-dimensional magnetohydrodynamic simulations accounting for ohmic dissipation, we investigate the long-term
evolution of the infalling envelope for $\sim 100,000$\,yr after protostar formation. The primary control parameter is the initial misalignment angle $\theta_0$ between the rotation axis and the
magnetic field, varied from $0^\circ$ to $90^\circ$. In all misaligned models ($\theta_0 \ne 0^\circ$), the pseudodisk (or infalling envelope) surrounding the circumstellar disk develops a highly distorted and complex morphology. Gas
accretion from the envelope proceeds through discrete, channel-like flows, producing asymmetric streams rather than axisymmetric infall. Protostellar outflows are launched even in these complex environments, and inflow and outflow regions are strongly interwoven. Outflows transport angular momentum anisotropically, leading to time-dependent changes in disk orientation and outflow direction, which further enhance envelope asymmetry. We examine the relative orientation between gas flows and
magnetic fields and find that, although statistical tendencies exist,
accretion streams cannot be uniquely characterized as either parallel or perpendicular to the
magnetic field, particularly in strongly misaligned cases. We also show that most infalling gas accretes at nearly the free-fall velocity, with only a minor fraction significantly slowed within the pseudodisk. Asymmetric
accretion and stream-like structures persist beyond 10,000\,au, demonstrating that large-scale asymmetry can arise intrinsically. Our results show that complex streams and asymmetric envelopes naturally emerge from magnetized core physics, even in the absence of initial
turbulence or external gas
accretion.
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Astrophysics of Galaxies · Cross-listed from astro-ph.SR
Tracing Accretion and Inner-Disk Gas Evolution in the Orion Nebula via Br-alpha and CO
Konstantin V. Getman, Maria Claudia Ramirez-Tannus, Jenny Frediani et al. (+17 more)
We present a systematic spectroscopic study of hydrogen Brackett-alpha (Br-alpha) and carbon monoxide (CO) fundamental-band (4.3-5.2 micron) emission from a homogeneous sample of 0.2-1.5 Msun pre-main-sequence (PMS)
stars in the Orion Nebula observed with JWST/NIRSpec-MOS as part of our Chandra-JWST project. Using 73 Br-alpha and 46 CO spectra, we investigate correlations between warm-gas emission, stellar properties,
accretion, and environment with censored correlation and regression analyses accounting for multiple testing. Br-alpha luminosity correlates strongly with
accretion luminosity (Lacc), even after excluding sources within 2' of Theta1 Ori C, the nebula's main ionizing O-type
star, whose radiation may bias proplyd Lacc estimates. This supports Br-alpha as a robust empirical tracer of
accretion in PMS
stars. Br-alpha also correlates with visual extinction (Av) and more weakly with stellar bolometric luminosity and mass. CO fundamental-band luminosities likewise correlate positively with Lacc and Av, relationships that persist in a larger combined JWST/NIRSpec+MIRI sample spanning multiple
star-forming regions. In contrast to Br-alpha, CO luminosity shows no significant dependence on basic stellar properties, suggesting that warm molecular gas is governed primarily by
accretion and local disk conditions. The weaker correlations of the Spitzer/IRAC spectral slope with Lacc and Av suggest that warm inner-disk gas may evolve or disperse faster than optically thick dust. Overall, the CO results tentatively indicate declining warm-gas emission as disks evolve, modulated by
accretion-powered thermal and ultraviolet excitation, although variations in emitting area inherited from natal core conditions may also contribute.
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All authors Konstantin V. Getman, Maria Claudia Ramirez-Tannus, Jenny Frediani, Kevin L. Luhman, Eric D. Feigelson, Bayron Portilla-Revelo, Christian Rab, Valentin Brunn, Jan Forbrich, Thomas J. Haworth, Rens Waters, Arjan Bik, Charles J. Law, Andrew J. Winter, Vladimir S. Airapetian, Abygail R. Waggoner, Michael A. Kuhn, L. Ilsedore Cleeves, Sergio A. Dzib, Marco Padovani
Astrophysics of Galaxies
Galactic Outflows and Star-Formation Quenching: A JWST Perspective
Rebecca L. Davies and Sirio Belli
Outflows driven by active galactic
nuclei (AGN) are widely considered a key mechanism for regulating and quenching
star formation in massive
galaxies. However, direct observational evidence linking outflows to quenching has remained elusive for decades. This article reviews recent findings for massive
galaxies at
cosmic noon ($z\sim 2$), based on sensitive James Webb Space
Telescope (JWST) observations tracing both
star formation histories (through Balmer absorption lines) and neutral outflows (through blueshifted NaID absorption). Neutral outflows are found in $\sim$ 25 - 50% of massive ($\log(M_*/M_\odot)>$ 10)
galaxies, independent of
star formation rate. Outflows from
star-forming
galaxies are consistent with being powered by
star-formation and/or AGN activity, whereas outflows from quiescent systems are generally attributed to current or previous AGN activity. There is growing evidence that recent rapid quenching of
star-formation is associated with powerful AGN-driven outflows with mass loading factors $\eta \gtrsim$ 1 - 10. The neutral gas dominates the outflow mass budget but in most cases its velocity is below the
halo escape velocity, indicating that this gas may form part of a galactic fountain. Detections of neutral gas inflows and residual cold gas reservoirs in quiescent
galaxies suggest that other feedback mechanisms such as AGN heating are required to keep
galaxies quenched over long timescales. We highlight the potential of multiphase outflow measurements to constrain feedback models, describe the main systematic uncertainties in mass outflow rate measurements, and discuss how the $z\sim 2$ results inform our understanding of the formation of the earliest massive quiescent
galaxies.
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Astrophysics of Galaxies
Emergence of high-mass stars in complex fiber networks (EMERGE) VII. Multi-Tracer Column Density Synthesis
Alvaro Hacar, Andrea Socci, Mario Tafalla et al. (+1 more)
Obtaining accurate estimates of the gas column density $\mathrm{N(H_2)}$ is crucial to determine the physical conditions of the molecular gas in the Interstellar Medium. This paper introduces the "Multi-Tracer Column Density Synthesis" (MT-CDS) technique, a new empirical approach to derive high dynamic-range column density maps with interferometers such as ALMA. We have compared the integrated intensity maps of two density selective tracers, namely HNC (1-0) and $\mathrm{N_2H^+}$ (1-0), obtained with IRAM-30m with ancillary Herschel column density estimates in seven
star-forming regions in Orion and derived individual temperature-corrected conversion factors for each of these tracers. We applied these conversion factors obtained at low-resolution into similar high sensitivity ALMA observations to derive independent column density maps describing both the low $N_\mathrm{HNC}\mathrm{(H_2)}$ and high $N_\mathrm{N_2H^+}\mathrm{(H_2)}$ column density components at high spatial resolution (4.5"). We also combined these independent maps into estimates for the total gas column density gas $N_\mathrm{tot}\mathrm{(H_2)}$ sampling more than two orders of magnitude in column density between $\sim 10^{21.5}-10^{23.5}$ cm$^{-2}$. A comparison with independent ArTeMiS column density maps at intermediate resolution (8") shows typical deviations of $\lesssim$0.2 dex from our MT-CDS gas column density estimates. We obtained individual column density maps in five of our targets at $\sim$2000 au resolution in which ALMA observations were available, that is a factor of $\sim$5 better than originally calibrated. These results demonstrate the potential of this MT-CDS technique to retrieve accurate, high dynamic range $N\mathrm{(H_2)}$ total gas column density estimates at interferometric resolution combining multiple molecular line tracers.
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All authors Alvaro Hacar, Andrea Socci, Mario Tafalla, Francesca Bonanomi
Astrophysics of Galaxies
SQuIGGLE: Radio AGN Found Predominantly in Young, Gas-rich Post-starburst Galaxies at z ~ 0.7
Vincenzo R. D'Onofrio, Justin S. Spilker, Krista L. Smith et al. (+13 more)
The processes that rapidly quench massive
galaxies and maintain their quiescence remain poorly understood. Substantial molecular gas reservoirs can survive this shutdown in post-starburst
galaxies, raising the question of what prevents the remaining gas from efficiently forming
stars. We present deep, subarcsecond VLA 6 GHz observations of 52 massive SQuIGGLE post-starburst
galaxies at $z\sim0.7$ to test the prevalence and mechanical impact of
radio activity during the gas-rich post-burst phase. We detect 6 GHz continuum emission in 18/52
galaxies ($\approx$35%), spanning $\log(L_{1.4\,{\rm GHz}}/{\rm W\,Hz^{-1}})\simeq23.0$–$25.0$ and generally exceeding the contributions expected from ongoing
star formation and the fading starburst, favoring an AGN origin. Ancillary data at other wavelengths provide little evidence for a population of luminous, radiatively efficient AGN, suggesting that these sources are instead dominated by comparatively weak, mechanically powered
radio AGN.
Radio activity is strongly concentrated within the first $\sim$200 Myr post-burst and is predominantly associated with
galaxies retaining substantial gas reservoirs. Above a common
radio luminosity threshold, the
radio detection fraction is enhanced by a factor of $\approx$2.5 relative to the
radio AGN candidate fraction in mass- and
redshift-matched quiescent LEGA-C
galaxies, primarily due to lower power sources. For efficient jet–ISM coupling, the inferred mechanical power could supply the approximate energy required to unbind the molecular gas on timescales comparable to its observed decline. Together, these results identify a population of radiatively inefficient AGN hosted predominantly by young, gas-rich post-starburst
galaxies at $z\sim0.7$ and suggest that they may have a role in maintaining inefficient
star formation.
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All authors Vincenzo R. D'Onofrio, Justin S. Spilker, Krista L. Smith, Rachel Bezanson, Robert Feldmann, Alex J. Geiger, Andy D. Goulding, Jenny E. Greene, Mariska Kriek, Anika Kumar, Yuanze Luo, Desika Narayanan, David J. Setton, Katherine A. Suess, Margaret E. Verrico, Pengpei Zhu
Astrophysics of Galaxies
Are Broad Mg II Galaxies Fading AGN?
Stephanie M. LaMassa, Michael Eracleous, Jessie Runnoe et al. (+2 more)
We analyzed a sample of 494
galaxies from the Sloan Digital Sky Survey (SDSS) I-IV that have unusual properties. They display broadened Mg II $\lambda$2798 line emission, as would be expected of Type 1 active galactic
nuclei (AGN). However, they have weak or absent broad Balmer lines though broadened Balmer lines often accompany broadened ultraviolet lines in Type 1 AGN spectra. We performed a spectral decomposition of these "broad Mg II
galaxies” to assess whether they can be considered fading AGN. The Balmer lines are more responsive to changes in the AGN continuum than the Mg II line. As the AGN power source fades, broad H$\beta$ and then H$\alpha$ will weaken and eventually disappear, leaving broad Mg II as a signpost of a more active past. In support of this interpretation, we found that broad Mg II
galaxies have weaker AGN luminosities and lower
accretion rates (parameterized by the Eddington ratio) than typical Type 1
quasars from SDSS. The Eddington ratio of broad Mg II
galaxies are similar to dim-state changing-look AGN, with an average value $\lesssim$1%, which is the threshold at which the inner region of a geometrically thin
accretion disk is thought to evaporate and be replaced by a geometrically thick radiatively inefficient
accretion flow in stellar-mass black holes. Broad Mg II
galaxies may represent the penultimate stage in a changing-look AGN sequence prior to the complete disappearance of all broad lines.
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All authors Stephanie M. LaMassa, Michael Eracleous, Jessie Runnoe, Benny Trakhtenbrot, Gisella de Rosa
Astrophysics of Galaxies
MOSS III: MeerKATs view on the galaxy populations in two massive galaxy clusters
Robert Kincaid, Mark Sargent, Pascale Jablonka et al. (+5 more)
The MeerKAT Observations of the Saraswati Supercluster (MOSS) is an ongoing project attempting to study the
radio and optical properties of the core region of the Saraswati supercluster (z = 0.28) and will eventually entail a full survey of the entire supercluster region. Here we use
radio catalogs from previous deep pilot MeerKAT L-band (1.28 GHz) observations (angular resolution of 8 arcsec) of the core region of the Saraswati supercluster. The region hosts two
galaxy clusters representing distinct environments: The most massive cluster Abell 2631, and the second most massive cluster ZwCl2341, that is significantly more dynamically active. The deep
radio catalogs of these clusters were combined with spectroscopic
redshifts (mainly from DESI DR1 and SDSS DR16) and optical photometry catalogs of the cluster member
galaxy source population. We use these
redshifts together with the 1.4GHz MeerKAT flux densities to derive the dust-free
star-formation rate (SFR) and evaluate various trends in the
radio SFG and AGN
galaxy populations. We find that the actively merging cluster ZwCL2341 has an increased
star-forming
galaxy population compared to A2631 with up to 4 times more
star-forming
galaxies. When looking at SFG-related
radio processes we see s enhanced SF-related activity in ZwCL2341 with SF-related
radio processes dominates entirely over AGN-related
radio processes. This suggests that dynamically active environments associated with cluster assembly, such as mergers, have enhanced SF
radio-activity and increased SFG (both
radio and non-
radio)
galaxy population compared to lesser active systems.
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All authors Robert Kincaid, Mark Sargent, Pascale Jablonka, Bruno Slaus, Viral Parekh, Shishir Sankhayan, Sameer Salunke, Jean-Paul Kneib
Astrophysics of Galaxies
The connection between massive galaxies and their dark matter haloes from $z=0.25$ to $z \sim 4$ from the combined COSMOS, XMM-LSS and ECDF-S fields
Natalia Stylianou, Matt J. Jarvis, Rohan G. Varadaraj et al. (+4 more)
Understanding how
galaxies populate and grow within dark matter
haloes is essential for linking the observed
evolution of
galaxies to the hierarchical growth of structure. We present a
galaxy clustering analysis using optical and near-infrared data from the UltraVISTA and
VIDEO surveys covering $9.3$ deg$^2$ across the COSMOS, XMM-LSS and ECDF-S fields, $\sim 5\times$ larger than previous comparable studies, providing sufficient volume to determine the
halo occupation of the most massive
galaxies to $z\sim 4$. We measure the angular two-point correlation function for stellar-mass-selected
galaxies over $0.25<z<4$ and by combining the three fields, we reduce the
cosmic variance by a factor of $\sim2$ compared to the individual fields. The stellar-to-
halo mass ratio peaks at a
halo mass of $M_{h}\approx10^{12} {\rm M}_{\odot}$ and is a maximum at $z\sim 1$. For the most massive
galaxies, the peak
halo mass ($M_{h}^{\rm peak}$) increases from $z=1\rightarrow 0$, while the peak stellar mass in such
haloes remains approximately constant, indicating that at $z<1$ massive
galaxy formation becomes less efficient. We also find a steady increase in the satellite fraction since $z\sim 1$, from which we infer that massive
halos continue to grow hierarchically while their central
galaxies experience suppressed stellar-mass growth. We suggest this is due to the central massive
galaxies having their growth controlled by feedback from active galactic
nuclei feedback, likely from low-power
stochastic radio emission.
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All authors Natalia Stylianou, Matt J. Jarvis, Rohan G. Varadaraj, Peter W. Hatfield, Joel Hamlett, Catherine L. Hale, Tariq Yasin
Astrophysics of Galaxies
The convective-transition gap in 47 Tucanae with JWST
M. Scalco, L. R. Bedin, M. Libralato et al. (+3 more)
We report the detection of the convective-transition gap along the lower main sequence (MS) of the Galactic globular cluster (GC) 47 Tucanae using deep James Webb Space
Telescope (JWST) observations. We analyse the stellar luminosity function (LF) in the vicinity of the gap location using two independent colour-magnitude diagrams (CMDs). In both cases, the LF is characterised by a narrow gap followed by a discontinuous increase in the stellar number counts, and presents an overall morphology qualitatively consistent with that reported in previous studies. By modelling the observed LFs with an empirical likelihood model, we estimate the statistical significance of the observed feature. Additional JWST passbands exhibit similar signatures, providing further evidence for the presence of a discontinuity.
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All authors M. Scalco, L. R. Bedin, M. Libralato, M. Griggio, E. Vesperini, R. Gerasimov
Astrophysics of Galaxies · Cross-listed from astro-ph.SR
The mass functions of multiple stellar populations in 47 Tucanae
M. Scalco, J. Bruce, E. Vesperini et al. (+1 more)
We used a combination of James Webb Space
Telescope (JWST) and Hubble Space
Telescope (HST) observations to investigate the mass functions (MFs) of the different stellar populations in the globular cluster (GC) 47 Tucanae (NGC 104) over a wide stellar-mass interval. We identified the multiple populations along the lower main sequence using only JWST photometry and, in particular, colour combinations sensitive to variations in oxygen abundance. We derived the MFs of the first- and second-population (1P and 2P)
stars separately and found that in the low-mass regime, the present-day MF of the 1P population is significantly steeper than that of the 2P population, which appears nearly flat. We also present the results of a dynamical model showing that this behaviour requires a different initial mass function (IMF) for the 2P and the 1P populations in the 0.1-0.4 solar masses mass range, thus providing a new fundamental constraint for the study of the
star formation of multiple populations in GCs.
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All authors M. Scalco, J. Bruce, E. Vesperini, L. R. Bedin
Astrophysics of Galaxies · Cross-listed from astro-ph.SR
JWST observations of 47 Tucanae: I. The low-mass main sequence down to the hydrogen-burning limit
M. Scalco, R. Gerasimov, L. R. Bedin et al. (+4 more)
We present the first results of a series of studies based on JWST observations of the globular cluster 47 Tucanae (47 Tuc, or NGC 104) obtained with NIRCam. By combining new data with earlier JWST observations, we derive high-precision proper motions (PMs) over a multi-year baseline (of ~3 years) and construct a clean sample of cluster members extending to very faint magnitudes (F444W~24.25 mag, corresponding to ~0.077 solar masses, slightly above the estimated hydrogen-burning limit of 47 Tuc, ~0.074 solar masses) along the main sequence (MS). We investigated the presence of the low-mass MS kink previously identified in 47 Tuc using the new F090W and F444W photometry. No significant signature of the feature is found using these filters, consistent with its proposed physical interpretation as a consequence of the transition in carbon chemistry toward a methane-dominated
equilibrium in very low-mass
stars. A comparison with theoretical isochrones indicates that the stellar population near the bottom of the MS is likely dominated by oxygen-poor
stars, in agreement with previous findings. Using artificial-
star tests, we quantify the completeness of our sample and show that the requirement of PM-based membership significantly limits the detection of the faintest objects, indicating that current JWST observations of 47 Tuc are not sufficiently deep to reliably trace the cluster's brown dwarf cooling sequence. The mass function (MF) of 47 Tuc shows a structured behaviour, with a break at ~0.15 solar masses not associated with the onset of convection, and a mild but systematic radial variation consistent with mass segregation. Our analysis indicates that the MF shape in this mass regime is more complex than a simple power-law description. This feature in the MF may point to a presently unrecognised mechanism affecting the formation or dynamical
evolution of low-mass
stars in globular clusters.
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All authors M. Scalco, R. Gerasimov, L. R. Bedin, E. Vesperini, M. Griggio, D. Nardiello, J. Anderson
Astrophysics of Galaxies
Substructure-enhanced Collisional Relaxation in Stellar Systems
Jian-Yu Gu, Xiao-Bo Dong and Run-Yu Meng
Two-body collisional relaxation in stellar systems is conventionally estimated using the classical Chandrasekhar theory, in which a subject
star is assumed to be embedded in a homogeneous medium of field
stars and their velocity distribution taken to be isotropic and Gaussian. Real stellar systems, however, can exhibit pronounced spatial and kinematic substructures. We investigate how such substructures – particularly the non-classical spatial inhomogeneity – modify the two-body
diffusion coefficient. We retain
hyperbolic two-body encounters but generalize the encounter calculation by integrating explicitly over the spatial distribution $n(\mathbf{r})$, while evaluating the velocity contribution from the full distribution $f_v(\mathbf{v})$. This yields a separable tensor expression for the
diffusion coefficient. We find that spatial substructure produces the dominant enhancement. The enhancement of the
diffusion coefficient increases systematically as the effective fractal dimension $D_{\rm frac}$ decreases, $\log \zeta_r(D_\text{frac}) \sim \left(1-D_\text{frac}/3\right)^q$ with $q \approx 4.28$. For the observationally motivated case with $D_{\rm frac}\approx 1.5$, the enhancement is moderate, whereas substantially lower fractal dimensions produce much larger enhancements. In contrast, the anisotropic, power-law-tailed, and fractal-like velocity distributions modify the
diffusion coefficient only by factors of order unity. Our representative substructured model yields enhancement ratios $\zeta_r\simeq3.45$ and $\zeta_v\simeq1.33$ when the measured particle-number trends are extrapolated to $N=10^{11}$, corresponding to an overall enhancement of $\zeta\simeq4.6$. Therefore, within the two-body encounter framework and the commonly used separable distribution functions, the enhanced collisional relaxation still has little impact on the mean-field nature of typical galactic systems.
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Astrophysics of Galaxies
A Nonlinear General Implicit Runge-Kutta Integrator for Multifluid Charged Dust and Gas
Mengxuan Chen, Hui Li, Chong-Chong He et al. (+3 more)
Charged dust in magnetized gas is subject to aerodynamic drag and the Lorentz force, both of which can be difficult to model numerically in a fluid simulation where their characteristic timescales are shorter than the timestep set by the Courant condition. We present a two-stage general implicit Runge-Kutta (GIRK) source integrator for multifluid charged dust coupled to an ideal magnetohydrodynamic (MHD) gas, implemented in the open source GPU-accelerated quokka code. Drag and Lorentz forces are advanced together in one implicit source update, avoiding errors in the terminal drift that can arise when the two forces are advanced in separate substeps. The timestep is compared with a drag-Lorentz timescale to select between resolved and stiff branches. The resolved branch uses Gauss-Legendre coefficients, while the stiff branch uses a coefficient set designed to recover the terminal drift set by the drag-Lorentz balance. We also allow the dust stopping time and charge-to-mass ratio to depend on the evolving state, evaluating them separately at the two implicit stage states and solving the resulting nonlinear stage equations by Picard iteration. The source update conserves total gas-dust momentum, and its computational cost scales linearly with the number of dust species. Tests reproduce the expected drag damping and terminal drift, confirm the predicted gyromotion amplitude and phase errors, demonstrate accurate treatment of state-dependent source coefficients, and recover the expected wave, shock, and instability dynamics in dusty MHD flows.
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All authors Mengxuan Chen, Hui Li, Chong-Chong He, Benjamin D. Wibking, Mark R. Krumholz, Xue-Ning Bai
Astrophysics of Galaxies
GroArnold: A Framework for Constructing Action-based Models for Triaxial Galaxies and Dark Matter Halos
Jian-Yu Gu, Xiao-Bo Dong, Shi-Yan Zhong et al. (+1 more)
Action-based distribution functions $f(\mathbf{J})$ provide a powerful description of stellar systems. Consequently, the construction of physically accurate and dynamically stable $f(\mathbf{J})$ for galactic components has emerged as a key challenge in the field. In this study, we present GroArnold, a computational framework designed to construct analytical $f(\mathbf{J})$ expressions for axisymmetric and triaxial
galaxies and dark matter
halos. The framework integrates modules for $N$-body initial condition generation, $N$-body simulation, angle–action variable estimation, and distribution-function fitting into a unified workflow. It supports a wide range of density profiles and kinematic properties, and is uniquely designed to generate stable $N$-body models for user-specified galactic systems, with the aim of obtaining an $f(\mathbf{J})$ that approximates a dynamically stable and physically consistent state. To this end, we extend the triaxial Stäckel Fudge method of the TACT code, implemented in our Nbody-TACT module, to enable action estimation directly from $N$-body gravitational potentials. GroArnold provides a robust and flexible tool for deriving numerically empirical, explicitly analytical distribution functions for user-specified
galaxies or
halos, thereby facilitating a wide range of practical $f(\mathbf{J})$-based modeling applications. In addition, it serves as a powerful tool for investigating the dynamics of realistic triaxial
galaxies and
halos beyond the scope of traditional spherical or axisymmetric models. We assessed the accuracy of the output $f(\mathbf{J})$ by comparing its predicted spatial and velocity distributions with those of the input $N$-body snapshot, and confirmed that it provides a reasonably accurate representation of the input. The code is modular, publicly available, and designed to support future extensions and adaptations.
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All authors Jian-Yu Gu, Xiao-Bo Dong, Shi-Yan Zhong, Run-Yu Meng
Astrophysics of Galaxies
Wave Cold Dark Matter Can Reproduce the Radial Acceleration Relation in X-ray Elliptical Galaxies
Runyu Meng and Xiaobo Dong
Wave cold dark matter (wave CDM) is a well-motivated variant within the collisionless CDM paradigm, in which the de~Broglie wavelengths of ultralight
bosons become relevant on galactic scales. While many of the previous tests of wave CDM have focused on small-scale tensions involving solitonic cores and certain
soliton–
halo relations in
galaxies, the radial acceleration relation (RAR) provides a complementary test: for a given baryonic mass distribution, it probes whether the DM
halo can reproduce the observed total gravitational field. In this work we test wave CDM against the RAR using eight X-ray elliptical
galaxies from the compilation of Lelli et al. We perform a suite of 3D Schrödinger–Poisson simulations and evolve the wave-CDM
halos to virialized quasi-stationary states. For each
galaxy and each adopted
boson mass, we select the realization whose final snapshot most closely matches the empirical RAR. We find that the selected wave-CDM realizations for these elliptical
galaxies can reproduce the RAR without including baryonic feedback or dark-matter self-interactions. At the
boson mass $m_a=10^{-23}$eV, the combined fit to the eight
galaxies gives $a_0=1.19\times10^{-10}\,\mathrm{m\,s^{-2}}$, consistent with the canonical value inferred from disk
galaxies. When the
boson mass is varied over $3\times 10^{-24}$ eV $\le m_a \le 2\times 10^{-23}$ eV, the best-fit value of $a_0$ changes by only $\sim 11\%$, and this variation shows no systematic trend with $m_a$. This insensitivity to
boson mass arises because, over the radial range relevant for the RAR, the virialized
halos are supported mainly by their velocity field, whereas the
boson-mass-dependent
quantum-pressure term is dynamically subdominant. These results show that wave CDM can reproduce the RAR in elliptical
galaxies, and provide a new galactic-scale test of the model beyond the previous focus on solitonic cores.
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Astrophysics of Galaxies
The Dance of the Little Red Dots: Spectroscopy of Two Blue Companions at z = 3.9 and 5.5 Reveals Young, Metal-Poor Starbursts Merging with Their LRDs within a Few Hundred Myr
Fabio Pacucci and Pierluigi Rinaldi
The Little Red Dots (LRDs) are compact, red sources, abundant at $4 \lesssim z \lesssim 9$ and likely powered by massive black holes. Photometric studies have found blue companions around them, but none has yet been confirmed spectroscopically. This Letter presents the only two LRD-companion pairs with spectroscopy of both members in the literature: "Waltz" at $z = 3.9$ and "Tango" at $z = 5.5$, with projected separations of $3.6$ and $2.5$ kpc. Both companions lie at the
redshift of their LRD, within $132 \, \rm km \, s^{-1}$ and $57 \, \rm km \, s^{-1}$, and are physically identical, but $524$ Myr apart: starbursts $\lesssim 50$ Myr old, metal-poor ($0.2 \, \rm Z_\odot$), dust-free, dynamically cold, and as bright as the LRDs themselves in the rest-frame UV. The LRD in Waltz hosts a $\approx 3 \times 10^{6} \, \rm M_\odot$ black hole accreting at half the Eddington rate, a factor of a few above the birth mass of a direct collapse black hole, and is embedded in gas as metal-poor as its companion. Orbital modeling shows that Tango is bound in $81\%$ of the allowed orbits and that Waltz is bound if its host
halo exceeds $5 \times 10^{10} \, \rm M_\odot$. Both blue companions then merge with their respective LRD within a few hundred Myr. We conclude that we are observing what heavy seeding requires: a young black hole beside the metal-poor starburst that the synchronized-pair scenario predicts, in the last steps of a
cosmic dance that ends in a merger, and in a
galaxy seeded by its black hole.
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Astrophysics of Galaxies
EMRIs in Kerr Spacetime: The Role of Inclination Diffusion
Yael Alush, Nicholas C. Stone and Scott A. Hughes
Extreme mass ratio inspirals (EMRIs) are expected to be a major source of gravitational waves (GWs) for the future
Laser Interferometer Space
Antenna (LISA). An EMRI occurs when a compact object, driven by the emission of gravitational radiation, slowly inspirals into a massive black hole (MBH). The classical formation channel involves repeated two-body interactions within dense nuclear
star clusters. However, both EMRI event rates and the expected distribution of their orbital parameters remain highly uncertain. A major source of this uncertainty is the poorly constrained ratio between gradually inspiraling EMRIs and direct plunges, which do not produce detectable GWs. While most studies of astrophysical EMRI production focus on the Schwarzschild limit, previous work examining the Kerr metric found that the
spin of the central MBH can significantly affect the EMRI-to-plunge ratio. This enhancement depends sensitively on orbital inclination, yet earlier studies held inclination fixed. In this work, we develop the mathematical framework describing inclination
evolution driven by two-body encounters evolving along Kerr geodesics. By implementing 3D
diffusion into Monte Carlo simulations, we show that initially prograde orbits may evolve into retrograde states, thereby converting potential EMRIs into plunges or vice versa. We estimate the EMRI-to-plunge ratio and find that substantial MBH
spin enhances the EMRI rate by a factor of $\sim 2.5$. Additionally, even for a non-spinning MBH, modeling the orbits as relativistic geodesics rather than Newtonian trajectories increases the number of EMRIs by a similar factor of $\sim 2.5$. The distribution of Kerr EMRI inclinations has a substantial prograde bias that may aid in identifying the subset of loss cone EMRIs within large future EMRI samples.
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Astrophysics of Galaxies
How JWST is Revolutionizing Our View of Early Galaxy Formation
Rychard Bouwens
The James Webb Space
Telescope (JWST) has been revolutionizing our understanding of early
galaxy formation over its first four years of science operations. With un- precedented sensitivity, spatial resolution, and wavelength coverage from the near- to mid-infrared, JWST has enabled astronomers to identify hundreds of
star-forming
galaxies at
redshifts z>~8 (within ~650 million years of the Big Bang) through strong spectral breaks and characterize these
galaxies through sensitive spectroscopy. These capabilities have provided new insights into the stellar populations, neutral gas, nebular continuum emission, chemical enrichment, dust content, and ionization conditions of
galaxies during
cosmic dawn, revealing more numerous and brighter systems than anticipated from pre-JWST models. We discuss the implications of these discoveries for reionization, the buildup of stellar mass and metals, and the
evolution of
galaxy populations and luminosity functions. JWST is also revealing a new physical picture of early
galaxies, characterized by compact, clumpy
star formation, high gas fractions, and intense radiation fields. Despite much progress, many open questions remain, including the efficiency, intermittency, and stellar initial mass function (IMF) of early
star formation, conditions in the interstellar medium (ISM), masses, and structure of the earliest
galaxies, and the
topology of reionization. Resolving these open questions will require
lensing magnification, sensitive spectroscopy to > 5 micron, including with the Atacama Large Millimeter Array (ALMA), exploration to higher
redshifts, and larger, more complete samples, helping to clarify how the first
galaxies formed and evolved.
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Astrophysics of Galaxies · Cross-listed from astro-ph.CO
TNGC-SIDM I: Evolution of massive cluster mergers under the self-interacting dark matter paradigm
Wonki Lee, Dylan Nelson, Myungkook J. Jee et al. (+8 more)
Merging
galaxy clusters provide an ideal laboratory for testing the self-interacting nature of dark matter. In this paper, we present a pilot study of magnetohydrodynamical cosmological zoom-in simulations of two cluster mergers selected from TNG-Cluster, with $M_{\rm 200c} \sim 9\times10^{14}~M_\odot$ and $M_{\rm 200c}\sim 2\times10^{14}~M_\odot$. The simulations are performed with both standard collisionless cold dark matter (CDM) and self-interacting dark matter (SIDM), assuming an isotropic, velocity-independent cross-section of $\sigma_{\rm T}/m_\chi = 1~\rm cm^2~g^{-1}$, with an additional $0.5~\rm cm^2~g^{-1}$ run for the low-mass system, and the mass resolution and
galaxy formation model are unchanged from TNG-Cluster. We show how dark matter self-interactions produce an isothermal core in the dark matter
halo, generate unique substructures in the intracluster light, and introduce variation in the multi-wavelength observables of the intracluster
plasma. Using these simulations, we test the validity of observational probes for dark matter self-interactions in cluster mergers. We find that the shock-to-shock separation shows similar
evolution in the self-interaction models tested here, providing a reference for distinguishing the $\sim100-200~\rm kpc$-scale difference in
halo separation induced by self-interactions. Moreover, the dark matter
halo centroid of the main cluster in the massive cluster merger is offset from the brightest cluster
galaxy by as much as $\sim20~\rm kpc$, larger than the offset in the sub-cluster. This offset persists beyond 4 Gyr after the first pericenter passage. Our results indicate that sample selection plays a key role in testing the possible self-interacting nature of dark matter using cluster mergers, and that double
radio relic cluster mergers and massive clusters with evidence of an ancient major merger offer a promising testbed for this purpose.
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All authors Wonki Lee, Dylan Nelson, Myungkook J. Jee, Giulia Despali, Mark Vogelsberger, Annalisa Pillepich, Cian Roche, Kyle Finner, Hyungjin Joo, Daisuke Nagai, John ZuHone
Astrophysics of Galaxies
The Connection Between the Growth of Massive Black Holes and Their Dynamical Histories
Lee A. Whitaker, Michael Tremmel, Angelo Ricarte et al. (+1 more)
Massive black holes (MBHs) grow through both gas
accretion and mergers and it remains unclear how variations to MBH growth and dynamical histories contribute to the spread in empirical scaling relations between MBHs and their host
galaxies. We examine the ex- and in-situ growth of MBHs within large-scale cosmological simulations and compare the
evolution of an outlier population of under-grown MBHs to the general population. We use the Romulus25 uniform volume cosmological simulation and the RomulusC cluster zoom-in simulation to examine the growth and merger histories of MBHs. We identify central MBHs that are undergrown relative to other MBHs in similar mass
galaxies and investigate their
accretion, merger, and orbital histories within the simulations. The contribution of ex-situ growth increases with MBH mass, with mergers becoming increasingly important in the most massive
galaxies. We find no difference between cluster and field environments in terms of the importance of ex-situ growth, which is generally very low. Under-grown MBHs have experienced fewer mergers and have had complex dynamical histories, spending significant time 'drifting' within the
galaxy or 'competing' with another MBH. Other under-grown MBHs have experienced a 'late entrance' into a
galaxy which until then had no central MBH. Our results demonstrate that MBH assembly is dominated by in-situ growth, which in turn is impacted by the dynamical histories of MBHs within assembling
galaxies. Prolonged off-centre
evolution can suppress
accretion and contribute to the formation of under-grown central MBHs at $z=0$.
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All authors Lee A. Whitaker, Michael Tremmel, Angelo Ricarte, Priyamvada Natarajan
Astrophysics of Galaxies
Cosmic Evolution Survey: LOFAR 144 MHz imaging of the COSMOS field
E. Vardoulaki, T. Shimwell, M. J. Hardcastle et al. (+18 more)
We present the first deep, targeted LOFAR 144 MHz source catalogue of the COSMOS field, together with the first 144 MHz source counts in this field. The data comprise 48 h of observations. Over the 2.6 sq. deg. region adopted for the catalogue analysis, the final Dutch-array image reaches a median rms sensitivity of ~100 uJy/beam at an angular resolution of 15" x 6". The resulting catalogue contains 1984
radio sources; a peak S/N >= 5 selection is adopted for the resolved/unresolved classification and source-count analysis. We characterised the catalogue using Monte Carlo source-injection and recovery simulations, including dedicated simulations of extended sources, to quantify completeness, flux-density redistribution, and morphology-dependent source-recovery effects. The catalogue reaches 90% completeness at 1.48 mJy. The resulting Euclidean-normalised differential source counts are measured down to ~0.4 mJy and show good agreement with LoTSS DR3 144 MHz source counts and with the VLA-COSMOS 3 GHz counts scaled to 144 MHz, with ~5% of catalogue sources having multiple 3 GHz counterparts within a beam-matched search region. Comparison with the VLA-COSMOS 3 GHz catalogue shows good astrometric agreement, with median offsets of Delta_RA = 0.35" (+0.03"/-0.05") and Delta_Dec = -0.83" (+0.02"/-0.03"), approximately 6% of the corresponding synthesised-beam dimensions, and no significant radial dependence across the field. The resulting catalogue provides a low-frequency view of COSMOS and a reference
dataset for future deeper LOFAR observations and multiwavelength studies of this extensively characterised extragalactic field.
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All authors E. Vardoulaki, T. Shimwell, M. J. Hardcastle, L. Doukas, L. K. Morabito, C. L. Hale, M. T. Sargent, V. Smolčić, G. Zamorani, G. Gozaliasl, F. An, M. Aravena, A. L. Faisst, M. Vaccari, E. Treister, A. Finoguenov, P. Best, J. S. Kartaltepe, C. Casey, S. Jin, V. Mainieri
Astrophysics of Galaxies · Cross-listed from astro-ph.SR
Anchoring the Chromospheric Activity$-$Rotation Relation: A Study of the Pleiades and Group X
A. Núñez, M. A. Agüeros, J. L. Curtis et al. (+1 more)
We present a study of the rotation and the chromospheric H$\alpha$ activity of low-mass
stars in the $\approx$120 Myr-old Pleiades and the $\approx$400 Myr-old Group X open clusters. We combine published and new rotation periods ($P_\mathrm{rot}$) from TESS and ZTF, and use LAMOST, SDSS, and MDM spectra to measure H$\alpha$ equivalent widths (EWs). While overall the Group X distributions of $P_\mathrm{rot}$ and EWs are as expected, detailed comparisons to the Pleiades and to the 700-Myr-old
benchmark Praesepe produce some surprises. For F through mid K
stars, the Group X color$-$period sequence lies between those of the Pleiades and of Praesepe, as expected. But the $P_\mathrm{rot}$ for its late K and early M dwarfs and the Praesepe slow-rotator sequence overlap, indicating that the 700 Myr-old
stars have not spun down significantly despite being nearly twice as old as their Group X counterparts. In the Rossby number$-L_\mathrm{H\alpha}/L_\mathrm{bol}$ plane, rapid rotators in Group X are saturated, as is seen in older clusters, whereas the rapid rotators in the Pleiades show a weak but measurable dependence of $L_\mathrm{H\alpha}/L_\mathrm{bol}$ on rotation. This implies that the chromospheric activity$-$rotation relation attains its mature form between 120 and 400 Myr. Dividing the sample by color reveals that K, M0, and M1 dwarfs are no longer saturated by $\approx$120 Myr, M2 and M3 dwarfs become unsaturated between $\approx$400 and $\approx$700 Myr, and later M dwarfs remain largely saturated through field ages even as their saturated $L_\mathrm{H\alpha}/L_\mathrm{bol}$ levels decline, indicating that chromospheric
evolution is not determined by rotation period alone.
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All authors A. Núñez, M. A. Agüeros, J. L. Curtis, C. A. Ospinal Achicanoy
Astrophysics of Galaxies · Cross-listed from astro-ph.HE
The ePESSTO+ census of ZTF nuclear transients. I. What flares in galactic nuclei?
E. Concepción, T. Petrushevska, G. Leloudas et al. (+21 more)
Transients in galactic
nuclei arise from distinct processes, only some of which trace the supermassive black hole (SMBH). These include tidal disruption events (TDEs), changing-look active galactic
nuclei, Bowen fluorescence
flares (BFFs) and ambiguous nuclear transients, alongside
supernovae that appear nuclear but are unrelated to the SMBH. Reliable classification requires spectroscopy, which will not scale to the alert volumes of the Legacy Survey of Space and Time (LSST). We aim to characterise the population of nuclear transients, to identify early observables capable of distinguishing SMBH-related
flares, and TDEs in particular, from the dominant
supernova background, and to assess the biases this selection introduces. We implemented a real-time filter on the Lasair broker, selecting transients from the Zwicky Transient Facility (ZTF) alert stream by nuclear coincidence with the host
galaxy, with no photometric cuts, to retain SMBH-related
flares in both quiescent and active hosts. The filter ran over 16 months, with candidates reported for classification through ePESSTO+ and other facilities. The filter returned 476 candidates, of which 202 were spectroscopically classified, yielding predominantly
supernovae, 10 confirmed TDEs (5%) and one BFF. The mean g-r colour and the rise time separate TDEs from the
supernova background. Our filter recovers 10 of the 25 TDEs classified in the same period and declination range; most misses are technical or observational rather than physical. Simple real-time filtering combined with basic photometric criteria can already isolate TDEs efficiently from nuclear transient alert streams, and high completeness is achievable. In the LSST era, where samples will be predominantly photometric, selection bias will become as important as contamination, and retaining
flares in active hosts is necessary if unusual events are not to be excluded.
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All authors E. Concepción, T. Petrushevska, G. Leloudas, D. Ilić, M. Gromadzki, S. Bhattacharyya, P. Charalampopoulos, A. Gomboc, N. Ihanec, M. Nicholl, P. J. Pessi, D. R. Young, P. Wiseman, T.-W. Chen, M. Dennefeld, Y. Dgany, C. P. Gutiérrez, C. Inserra, L. Makrygianni, T. E. Müller-Bravo, S. Nissen, F. Onori, R. Roy, M. Quilt
Astrophysics of Galaxies
Dynamical formation of dormant black holes: Predictions for Gaia DR4
Daniel Marín Pina, Michela Mapelli, Giuliano Iorio et al. (+1 more)
Dormant black holes (dormant BHs, i.e., X-ray quiet binaries comprising a BH and a companion
star) are probes of the effect of cluster dynamics and binary stellar
evolution on compact-object binaries. A dozen dormant BH binaries are known, a number that will increase substantially with the upcoming Gaia Data Release 4 (DR4). Their origin is uncertain, and dynamical formation is proposed as one possible channel. Here, we study the formation of dormant BHs in low-mass
star clusters, accounting for the interplay of binary stellar
evolution and cluster dynamics. We present new simulations with the $N$-body code PeTar, interfaced with the population synthesis code SEVN for single and binary
star evolution. Our grid spans a range of cluster masses ($300-4800\,$M$_\odot$),
metallicities ($1.4\times10^{-2}$, $1.4\times10^{-4}$), and natal kick models (with and without fallback). We find that almost all dormant BH binaries escape the parent cluster within $\sim1\,$Gyr ($\sim10\,$Myr) when assuming weak (strong) natal kicks. Most ($73\%$) dormant BHs form via the exchange of a BH (or its progenitor
star) into a stellar binary, or of a
star into a binary with a BH. Dormant BHs in low-mass clusters have a wide orbital period distribution (from a few hours to $10^8\,$d), with an upper limit set by natal kicks, a bimodal eccentricity distribution (a first peak at zero eccentricity for circularised systems and a second at high eccentricity), and stellar masses that follow the (evolved) initial mass function. Large BH masses are a smoking gun of dynamical formation, via exchanges and stellar collisions. We expect Gaia DR4 to contain $\sim1-64$ high-
metallicity and $\sim0.4-48$ low-
metallicity dormant BHs, with a period distribution peaking at $\sim10^3\,$d, $\gtrsim90\%$ of them with eccentricity $e>0.1$, and $\sim20\%$ with large BH masses ($m_{\rm BH} \gtrsim 30\,$M$_\odot$).
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All authors Daniel Marín Pina, Michela Mapelli, Giuliano Iorio, Cecilia Sgalletta
Astrophysics of Galaxies
Massive double-exponential galaxies with extended LSB emission: An IllustrisTNG exploration II -are they unique?
Suchira Sarkar, Kanak Saha and Anshuman Borgohain
The massive disk
galaxies (stellar mass >= 10^11 M_solar ) in the local universe (z < 0.1) encode challenging aspects of
galaxy formation physics. We have studied one class of such
galaxies - the giant low surface brightness
galaxies (gLSBs) that show a hybrid morphology - a central Sersic, an inner high surface brightness, exponential stellar disk surrounded by an outer, extended low surface brightness disk, using large volume IllustrisTNG-100 simulation. This is motivated by the recent observation of several such systems and an earlier work by Sarkar & Saha (2025) from IllustrisTNG-50. We find that despite using a ~ 10 times larger volume simulation, only ~11% of massive disk
galaxies show such morphology, consistent with findings from TNG50. This shows robustly that such
galaxies are not common in the local universe. We compared them with the typical disk
galaxies from observations, and single-exponential gLSBs from TNG100. We show that while the inner disk components lie well within the central surface brightness vs. radial scale length distribution of the typical disks, the outer LSB disks lie significantly at the outskirt, occupying a unique space. Their median bulge-to-total ratio is ~ 0.2 making them disk dominated, similar to the typical disks and the single-exponential gLSBs. We find their median dark matter mass fraction to be high (~ 0.9), typical of gLSBs. The outer LSB disks reach fainter central surface brightness and larger scale length values than the single-exponential gLSBs. Our exploration will be useful in understanding their formation mechanism across
cosmic time.
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Astrophysics of Galaxies
Black hole spin-mass correlation and accretion disks at birth stage of dense star clusters
Zacharias Roupas
We review the
accretion-driven channel of stellar black-hole growth and
spin-up in gaseous
star clusters, developed within the framework of our MSCA project "protoBH". Our detailed calculations involving semi-analytic modelling, dynamical and hydrodynamic simulations suggest that the growth and
spin-up of initially low-mass stellar black holes is an integral element of the formation process of dense massive
star clusters, such as the proto-globular clusters observed at high
redshift. The black holes accrete residual gas, remaining from the first
star formation event, and form
accretion disks generated by gas angular momentum induced by the black-holes' own curved orbits. Assuming initial black hole masses below the pair-instability mass gap $\leq 55\,{\rm M}_{\odot}$, the gap gets populated with black-hole masses growing to $\sim 10^2\,{\rm M}_{\odot}$, and even reaching several hundred solar masses for sufficiently dense and massive proto-clusters. We predict a consistent
spin-mass relation with low black hole
spins $\lesssim 0.2$ for low black hole masses $\lesssim 20\,{\rm M}_{\odot}$, spanning all intermediate
spins for higher masses and saturating to high
spins $\gtrsim 0.8$ for high masses $\gtrsim 70\,{\rm M}_{\odot}$. We find evidence in favour of such an
accretion-driven subpopulation of black holes in the GWTC-5.0 released by the LIGO-Virgo-KAGRA collaboration.
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Astrophysics of Galaxies · Cross-listed from astro-ph.HE
Broadband non-thermal emission predictions based on 3D simulations of supernova explosions within active galactic nuclei jets
B. Longo, V. Bosch-Ramon, M. Perucho et al. (+1 more)
Thermonuclear and core-collapse
supernovae are statistically expected to happen within extragalactic jets, as these jets cross the inner regions of their host
galaxies, and
supernova ejecta-jet interactions can potentially lead to strong non-thermal activity. We model the non-thermal emission from a
supernova interacting with a jet on kiloparsec scales, using detailed numerical simulations of the interaction. Using a post-processing method, we applied a non-thermal model of the acceleration and transport of electron and their synchrotron and inverse Compton emissions, simplified and tuned for flexibility and computational speed, to the results of a three-dimensional relativistic hydrodynamics simulation of the ejecta of a
supernova interacting with an extragalactic jet. For intermediate jet powers,
radio, optical and X-ray fluxes from
supernova ejecta-jet interactions may be detectable for distances < 100Mpc. The non-thermal luminosity budget and local conditions associated with these interactions could be enough to explain
knots seen in kiloparsec scale jets at different energies. These conditions might also be suitable for the production of heavy ultra high-energy
cosmic rays, but
photon and
neutrino generation from hadronic processes would be minor on kiloparsec scales. The leptonic gamma-ray fluxes are modest but might non-negligibly contribute in TeV for the nearest or more powerful jet sources.
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All authors B. Longo, V. Bosch-Ramon, M. Perucho, J.M. Martí
Astrophysics of Galaxies
EDGE-INFERNO: The chemical signatures of assembly history in reionization fossils
Eric P. Andersson, Martin P. Rey, Alexander P. Ji et al. (+9 more)
In
galaxies, stellar populations represent a superposition of both in situ and accreted components, tracing internal chemical
evolution as well as the histories of merged satellites. We investigate how assembly history shapes the chemical properties of present-day stellar populations in low-mass dwarf
galaxies. We analyze a suite of EDGE-INFERNO
star-by-
star cosmological zoom-in simulations of
galaxies with present-day
halo mass $\sim1.4\times10^9\,{\rm M}_{\odot}$. We systematically vary
galaxy growth while preserving the present-day
halo mass, engineering our simulations to span a continuum of assembly histories. Early-forming systems form most of their
stars in a single progenitor, with centrally concentrated
star formation and a continuous enrichment history. In contrast, our late-forming systems assemble by
accretion of multiple progenitors with their own stellar populations, resulting in fragmented
star formation across several
halos with independent chemical
evolution tracks. These regimes produce qualitatively different chemical signatures: single-progenitor systems exhibit connected, well-defined trends in abundance space, while multi-progenitor systems show multiple, distinct stellar populations with limited overlap. We find that
metallicity distribution functions provide initial constraints on assembly history for samples of at least $50$-$100$ member
stars. Multi-element abundance analysis significantly improves the recovery of distinct components, although robust reconstruction still requires larger samples. Fully separating in situ and accreted populations likely requires kinematic information. Accreted
stars can contribute substantially even at high
metallicities in multi-progenitor systems, while external enrichment can cause accreted material to follow similar chemical trends as in situ
stars, particularly in the single-progenitor regime.
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All authors Eric P. Andersson, Martin P. Rey, Alexander P. Ji, Justin I. Read, Oscar Agertz, Alexander H. Riley, Stacy Y. Kim, Astha Chaturvedi, Jennifer Mead, Kaley Brauer, Mordecai-Mark Mac Low, Andrew Pontzen
Astrophysics of Galaxies · Cross-listed from astro-ph.HE
Delving into the depths of NGC 3783 with XRISM VI. Evidence for a failed wind based on Fe xxv absorption line variability
Chen Li, Jelle S. Kaastra, Liyi Gu et al. (+7 more)
NGC 3783 exhibits a prominent Fe XXV absorption trough in the time-averaged XRISM/Resolve spectrum. To investigate its short-term variability, we present a time-resolved analysis of the Fe XXV absorption line during the continuous 10-day observation. We divided the resolved absorption profile into five fixed velocity intervals and measured their normalized equivalent widths in 19 time-resolved spectra. Three velocity intervals exhibit significant equivalent-width (EW) variability. Two velocity intervals respond differently to low- and high-flux states with less emission line contamination. The time-dependent photoionisation modelling is unable to reproduce the most significant observed EW variation ($3.5 \, \sigma$), possibly owing to uncertainties in the assumed initial
equilibrium state, which prevent a precise density measurement. Instead, using photoionisation calculations and assuming the high-density limit, we derive approximate constraints on the ionisation parameters of the two relevant components. The low-velocity component (-320 to -680 km/s) shows a delayed inverse response, indicating a high ionisation parameter, while its relatively short lag timescale indicates a relatively high density and a distance upper limit of 0.05 pc. In contrast, the high-velocity component (-680 to -1040 km/s) manifests a positive response with a longer lag to the ionising continuum, implying a relatively low ionisation parameter. This component appears to be less dense, with an inferred distance upper limit of 0.25 pc. The low-velocity component is consistent with a failed wind, as its outflow velocity is below the local escape velocity, whereas the high-velocity component lies near the escape threshold. Together with the lower-ionisation failed wind detected in 2001, this supports a multiphase failed-wind scenario in the unobscured state of NGC~3783 over more than two decades.
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All authors Chen Li, Jelle S. Kaastra, Liyi Gu, Missagh Mehdipour, Keigo Fukumura, Matteo Guainazzi, Misaki Mizumoto, Ehud Behar, Shoji Ogawa, Keqin Zhao
Astrophysics of Galaxies
EMU detection of mysterious multiple component radio-continuum emission from nearby spiral Seyfert I type galaxy 'Sand-timer' (NGC 7213)
M. D. Filipović, Z. J. Smeaton, B. S. Koribalski et al. (+24 more)
We present an Australian Square Kilometre Array Pathfinder (ASKAP) Evolutionary Map of the Universe (EMU)
radio-continuum detection of the nearby spiral Seyfert I type
galaxy NGC 7213 which we nickname `Sand-timer' due to its morphological appearance. We find intriguing, peculiar emission extending from the central supermassive black hole (SMBH), which we refer to as
galaxy hyperbubbles and/or active galactic
nucleus (AGN) jets. Finally, we find two previously undetected kiloparsec-scale features in the polarised intensity image, which appear most likely also related to the central SMBH, as restarted bipolar
radio jets, though somewhat obscured in the
radio-continuum total intensity image. They resemble the bow shocks often seen in Fanaroff-Riley Class II (FR-II)
radio galaxies, and so we propose they most likely represent an early episode of the `Sand-timer's' AGN jet activity. An alternative scenario is that the core of NGC 7213 may be a supermassive binary black hole (SMBBH) undergoing a tidal disruption event (TDE), potentially causing the peculiar
radio-continuum emission.
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All authors M. D. Filipović, Z. J. Smeaton, B. S. Koribalski, R. Kothes, A. Ahmad, R. Z. E. Alsaberi, C. Bordiu, A. C. Bradley, E. J. Crawford, A. M. Hopkins, E. Järvelä, S. Lazarević, D. Leahy, J. L. Payne, S. F. ur Rahman, G. P. Rowell, H. Sano, M. Selby, S. S. Shabala, E. J. Stanton, S. Taziaux, K. Tsuge, D. Urosević, N. F. H. Tothill, J. Th. van Loon, V. Velović, G. L. White