Astrophysics of Galaxies
SAMI and TNG-Cluster: tracing galaxy spin and environmental transformation across cluster phase-space and cosmic time
Gustavo F. Gonçalves, Ilaria Marini, A. Fraser-McKelvie et al. (+4 more)
The dense environment of
galaxy clusters suppresses
star formation and alters the kinematic properties of infalling satellites through gas stripping, tidal interactions, gravitational harassment and starvation. Projected phase-space diagrams connect the present-day distribution of cluster
galaxies to their
accretion histories. We combine SAMI
Galaxy Survey integral field spectroscopy with the TNG-Cluster simulation to investigate how the stellar
spin parameter ($\lambda_R$), $(g-i)$ colour, and sSFR vary across projected phase-space infall regions. At $z = 0$, TNG-Cluster reproduces the direction and broad strength of the phase-space trends observed in SAMI, including the weak yet significant $\lambda_R$-clustercentric distance correlation. Leveraging this agreement, we extend the analysis across the last 8 Gyr, tracing the statistical
evolution of
galaxy properties within each infall region, and complement this with individual orbital histories of representative satellites. While colour and sSFR show clear monotonic gradients with both phase-space position and
cosmic time, $\lambda_R$ behaves differently: it remains largely uniform across the outer infall regions, with only the virialised core exhibiting systematically lower values, and displays a slow monotonic decline toward the present day across all regions. We find that angular momentum suppression driven by the cluster environment is a slow, cumulative process requiring several Gyr of exposure to the cluster core, modulated by orbital history and stellar mass. This gradual nature explains why the $\lambda_R$-environment correlation appears weak across phase-space regions in statistical samples; the effect emerges when individual satellite histories are tracked, revealing a sustained dynamical response to prolonged cluster residence.
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All authors Gustavo F. Gonçalves, Ilaria Marini, A. Fraser-McKelvie, Natan de Isídio, Rubens E. G. Machado, Richards P. Albuquerque, Daudi T. Mazengo
Astrophysics of Galaxies
NOCTURNE. II. Extreme radio variability in the heart of early-stage active galactic nuclei
Emilia Järvelä, Patrizia Romano, Anne Lähteenmäki et al. (+1 more)
We report the discovery of extreme 37 GHz
radio variability in early-stage active galactic
nuclei (AGN). Most of these sources belong to the class of narrow-line Seyfert 1 (NLS1)
galaxies, which harbour fast-growing, low-mass supermassive black holes that accrete at high Eddington ratios. At 37 GHz, these extraordinary AGN exhibit amplitude variability of three to four orders of magnitude over timescales of a few days. Notably, despite several attempts, we have not detected relativistic jets in these sources, suggesting that this phenomenon may occur very close to the black hole and may represent a new form of AGN variability. One of these sources, which flared at 37 GHz, was followed up with the Karl G. Jansky Very Large Array and Swift XRT/UVOT. Based on these observations, we estimated an e-folding timescale of mere hours, leading to variability brightness temperatures and variability Doppler factors that are extremely difficult to explain by an incoherent emitter. This suggests a possible detection of coherent emission from an AGN, although more observations will be needed to distinguish between alternative scenarios.
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All authors Emilia Järvelä, Patrizia Romano, Anne Lähteenmäki, Marco Berton
Astrophysics of Galaxies
Disentangling Stellar Mass and Environmental Effects on eROSITA AGN Activity using multi-wavelength data from GAMA, WISE, GALEX, and DESI Legacy Survey
Navya Saraswat, Shadab Alam and Subhabrata Majumdar
We use a stellar-mass complete sample of $\sim 36{,}000$
galaxies from GAMA/eFEDS to test whether AGN activity depends on environment independent of stellar mass. To isolate this effect, we introduce $\delta_{\rm rank}$, a novel local overdensity metric defined within narrow stellar mass bins. Our main result is that X-ray-selected AGNs show a clear environmental trend, the AGN fraction rises from $\sim 4\%$ in low-density regions to $\sim 6\%$ in high-density regions, with a sharp transition at $\delta_{\rm rank} \sim 0.4$. This environmental dependence is absent for WISE-selected and broad-line AGN, and Eddington ratios show no variation across environments. We also found that for
galaxies with $\mathrm{SFR} > 15\,M_\odot\,\mathrm{yr}^{-1}$, X-ray AGN fraction is approximately 5%, 60% and 20% in low, mid and high $\delta_{\rm rank}$
galaxies. We show that relationship between AGN fraction and SFR varies dramatically with both environment and selection method. We conclude that environment on scales of $\sim 5h^{-1}\,\mathrm{Mpc}$ regulates X-ray AGN triggering efficiency.
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Astrophysics of Galaxies · Cross-listed from astro-ph.HE
Formation of Merging Black Hole Binaries Inside Massive AGN Stars
Sizheng Ma, Douglas N. C. Lin and David A. Velasco-Romero
Stars embedded in the disks of active galactic
nuclei (AGN) can grow to hundreds of solar masses, and the same disks are expected to host a population of stellar-mass black holes. A
star may therefore capture passing black holes, turning its interior into a potential factory for forming compact binary black hole systems and, ultimately, for the gravitational-wave events seen by our detectors. We test how readily this channel operates using three-dimensional hydrodynamic simulations of black hole–
star encounters. As a proof of principle, we adopt a
star-to-black-hole mass ratio of $34\!:\!1$, and find that the capture does not disrupt the structure of the
star: it heats the
star by $10$–$30\%$, and the
star loses only $\lesssim1\%$ of its mass throughout. The captured black hole loses its orbital angular momentum rapidly to dynamical friction, sinking to the stellar center within a stellar dynamical time $\lesssim10^{4}\,$s. If the
star already harbors a black hole at its center, the two form a bound binary whose gravitational-wave coalescence time falls below $10^{4}\,$yr. Depending on the geometry and speed of the encounter, the resulting orbit may be nearly circular or retain substantial eccentricity. Our calculations confirm that black hole–
star encounters in AGN disks are indeed a viable channel for assembling stellar-mass black hole binaries and supplying sources for gravitational-wave detectors.
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Astrophysics of Galaxies
Cosmic Noon Galaxies in the Hubble Ultra Deep Field with MIRI Wide-Field Slitless Spectroscopy
S. Kendrew, G. Östlin, L. Colina et al. (+29 more)
We present results from a survey of the Hubble Ultra-Deep Field using the Wide-Field Slitless Spectroscopic (WFSS) capability of the Mid-Infrared Instrument (MIRI) on JWST, demonstrating the capabilities of this new mode. We describe the data reduction and calibration methodology, and estimate calibration uncertainties. From our observations we obtain spectra of 47
galaxies with confirmed spectroscopic
redshifts, with a maximum z_spec of 3.712. In the final sample we target in particular the 3.3 um Polycyclic Aromatic Hydrocarbon (PAH) feature, which has recently gathered interest as a
star formation rate indicator and diagnostic for the dust grain size distribution in
star forming
galaxies from the local Universe to intermediate
redshifts. The feature falls into the WFSS wavelength region for
redshifts 0.67 to 3.1 - providing full coverage of the peak
star formation “
Cosmic Noon” era (1 < z < 3) and connecting dust properties in this critical
galaxy evolution period with local-Universe and low-
redshift observations. Using the
galaxies in our sample in this
redshift regime, we test correlations identified in lower-
redshift samples in the near-infrared or targeted programs in the mid-infrared, finding the WFSS spectra, even with large calibration uncertainties, show good agreement with complementary samples. The 3.3 um PAH luminosities follow previously established correlations with total IR luminosity and SED-derived
star formation rates, confirming this feature's power as tracer of dust-obscured
star formation. Our work illustrate the potential of the MIRI WFSS mode for studies of
Cosmic Noon-era
galaxies in particular in an observationally efficient way.
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All authors S. Kendrew, G. Östlin, L. Colina, P. Rinaldi, J. Álvarez-Márquez, L. A. Boogaard, J. Melinder, J. P. Pye, A. Alonso Herrero, K. I. Caputi, A. Crespo Gómez, M. Garcia Marín, S. Gillman, S. Harish, E. Iani, D. Langeroodi, A. Labiano, P. G. Pérez-González, P. van der Werf, F. Walter, G. Wright, T. Greve, M. Güdel, T. Henning, P.-O. Lagage, T. P. Ray, B. Vandenbussche, E. van Dishoeck, S. Alberts, R. Fernandez Aranda, A. Petric, I. Shivaei
Astrophysics of Galaxies
Gravitational Wave Bias in IllustrisTNG300 from Machine-Learned Population-Synthesis Calibrated Merger Rates
Dorsa Sadat Hosseini, Taisiia Karasova, Nikshay Chugh et al. (+2 more)
The large scale clustering of gravitational wave (GW) sources offers an independent probe of cosmology and compact-binary astrophysics. Interpreting future GW clustering measurements requires understanding how merger rates depend on host-
galaxy properties and environment. We develop a simulation-based framework to model the clustering of binary black hole (BBH) mergers and estimate the corresponding GW bias. We populate IllustrisTNG300 with GW sources using a machine-learning emulator trained on the GALAXYRATE data set, which provides population-synthesis calibrated merger rates linked to
galaxy formation histories. This enables physically motivated mock GW catalogs with
galaxy-specific BBH merger rates that depend on stellar mass,
star formation rate,
metallicity, and
redshift. We compare this framework to a simpler phenomenological model in which the merger rate depends only on stellar mass. In both approaches, GW sources are more strongly biased than the overall
galaxy population, reflecting the preference for BBH mergers to occur in more massive, more strongly clustered
halos. The machine-learned model also produces stronger scale dependence in the GW bias than stellar-mass weighting alone, indicating that additional host properties affect GW clustering. We further find that
metallicity correlates positively with both GW and
galaxy bias. These results highlight the importance of physically motivated merger rate models for GW large scale structure analyses and provide a framework for interpreting future clustering measurements from experiments such as the Einstein
Telescope and
Cosmic Explorer.
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All authors Dorsa Sadat Hosseini, Taisiia Karasova, Nikshay Chugh, Alex Krolewski, Ghazal Geshnizjani
Astrophysics of Galaxies
Filament Formation via Collision-induced Magnetic Reconnection – Kinematic Features
Shuo Kong, Griselda Arroyo-Chávez, Volker Ossenkopf-Okada et al. (+4 more)
The Collision-induced
Magnetic Reconnection (CMR) mechanism has recently been proposed as a filament formation model that emphasizes the active role of
magnetic fields. To enable better observational tests with data from modern
telescopes, we provide more specific observable predictions for filaments formed via CMR. Two types of CMR kinematics are revealed in position-velocity (PV) diagrams. First, due to the nature of CMR, the midplane contains a converging motion close to the filament and two diverging motions farther from the filament. They exhibit a blueshift,
redshift, blueshift,
redshift (BRBR) velocity pattern along the line-of-sight when the collision midplane is inclined, giving rise to a special pattern in the PV-diagram. Second, the longitudinal PV-diagram along the filament spine exhibits a velocity oscillating pattern, which is currently attributed to the
magnetic transport of gas clumps in the converging motion. The first type of pattern involves emission primarily outside the filament, which can be confused with the environment. The second type, however, mainly emerges from gas inside the filament, thus more robust for observational tests. Both the integral-shaped filament and the Stick filament in the Orion A cloud show the velocity oscillation in PV-diagrams, although the spatial oscillation frequency and their velocity spread differ.
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All authors Shuo Kong, Griselda Arroyo-Chávez, Volker Ossenkopf-Okada, Héctor G. Arce, Ralf S. Klessen, Duo Xu, Szu-Ting Chen
Astrophysics of Galaxies
JWST Observations of Starbursts: A Young Bubble in NGC 253's Central Starburst
Kaitlyn E. Sheriff, Elisabeth A. C. Mills, Xinyu Mai et al. (+31 more)
We present a multi-wavelength analysis of a young bubble in the nuclear starburst of NGC 253 using new JWST MIRI-MRS observations together with archival ALMA (100, 350, 690 GHz) and Chandra data. The MIRI maps reveal a prominent bubble-like structure in both ionized and molecular emission lines. The bubble is spatially coincident with one of the least embedded massive young clusters detected with ALMA, suggesting that the cluster is driving the expansion. We measure a radius of $\sim 11.5 \pm 3.4$ pc and an expansion velocity of $\sim 90 \pm 44$ km s$^{-1}$, implying a dynamical age of $\sim 0.1 \pm 0.1$ Myr. Using RADEX modeling of multiple CO transitions, we infer a molecular mass in the range of $(1.3 \pm 0.3) \times 10^4$ to $(2.8 \pm 0.8) \times 10^5$ $M_\odot$. We derive a kinetic energy of order $10^{51}$-$10^{52}$ erg, consistent with mechanical input from Wolf-Rayet stellar winds or
supernovae in a $\sim 10^6$ $M_\odot$ cluster. The existence of a large population of Wolf-Rayet
stars or past
supernovae is supported by the presence of coincident X-ray emission. Our results provide direct evidence that individual clusters in a nuclear environment can carve out coherent structures on parsec scales and inject significant energy and momentum into the surrounding interstellar medium, which can contribute to the nuclear outflow in NGC 253.
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All authors Kaitlyn E. Sheriff, Elisabeth A. C. Mills, Xinyu Mai, Utsav Siwakoti, Sara E. Duval, Alberto D. Bolatto, Rebecca C. Levy, Jia Wei Teh, Torsten Böker, Serena A. Cronin, Daniel A. Dale, Keaton Donaghue, Kimberly Emig, Simon C. O. Glover, Rodrigo Herrera-Camus, Ralf S. Klessen, Thomas S.-Y Lai, Ashley E. Lieber, Laura Lenkić, Sebastian Lopez, David S. Meier, Jüergen Ott, J. D. T. Smith, Yu-Hsuan Teng, Paul P. van der Werf, Sylvain Veilleux, Vicente Villanueva, Rachel Cionitti, Joseph Havens, Maleah Rhem, Nathan Shaw, Kai Smith, Hazel B. Wright, Md. Abdullah Al Zaman
Astrophysics of Galaxies
Forged in Quenching: Morphological Transformation across Star-forming and Quiescent Galaxies in EAGLE
Kai Wang, Carlton Baugh, Sownak Bose et al. (+15 more)
The connection between morphology and quenching in central
galaxies is well established, but its physical origin remains widely debated. We address this by tracing the main progenitor branches of $z=0$
star-forming and quiescent central
galaxies in the EAGLE cosmological simulation from $z\gtrsim4$. Their disc-to-total ratio and triaxiality tracks are indistinguishable until $z\approx 1$-$2$, when both diverge concurrently with the onset of quenching, whereas the size and supermassive black hole (SMBH) mass differences are established earlier. We identify four physically distinct channels linking
galaxy morphology and quenching. First, mergers cause size growth, rotation suppression, triaxiality increase, and SMBH growth, with the accumulated SMBH mass subsequently causes the quenching of
galaxies. Second, with merger history controlled,
galaxy morphology modulates SMBH growth throughout the
star-forming phase: compact, dispersion-dominated
galaxies grow their SMBHs faster and are preferentially quenched, producing the size and morphology differences between
star-forming and quiescent
galaxies. Third, at fixed stellar mass and SMBH mass, compactness further facilitates the quenching of
galaxies. Fourth, disc instability transforms compact oblate discs into prolate systems, with substantial size growth and suppressed rotation but negligible stellar mass growth. This secular channel contributes about half of the prolate
galaxy population around $M_{\rm star}\approx 10^{10.6}\,\rm M_\odot$. Prior to quenching, the progenitors of quiescent
galaxies already have smaller sizes, lower disc-to-total ratios, and more massive SMBHs than
star-forming
galaxies at the same epoch, by amounts comparable to their differences at $z=0$. Morphology therefore plays an active role in growing the SMBH and quenching the
galaxy, rather than being passively inherited through progenitor bias.
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All authors Kai Wang, Carlton Baugh, Sownak Bose, Shaun Cole, Carlos S. Frenk, Hao Fu, Cedric Lacey, Shengdong Lu, Aaron Ludlow, Peder Norberg, Yingjie Peng, Katy L. Proctor, Isabel Santos-Santos, Francesco Shankar, Tom Theuns, Enci Wang, Tao Wang, Vivienne Wild
Astrophysics of Galaxies
The Missing Black Hole in the Large Magellanic Cloud: A Dynamical Prediction for Its Present-Day Location
Robin Chisholm, Elena D'Onghia, Niv Drory et al. (+2 more)
There are indications that the Large Magellanic Cloud (LMC) hosts a central supermassive black hole (SMBH), yet no direct detection exists: one reason is that its present-day location need not necessarily coincide with the photometric or kinematic centers. Here we frame a dynamical targeting problem and predict the present-day sky location of the LMC SMBH. We model the recent LMC-Small Magellanic Cloud (SMC) interaction, which induces a bar-disk offset, and integrate SMBH orbits within a realistic, time-dependent LMC-SMC-Milky Way (MW) potential. We show that the MW tidal field at present epoch exceeds that of the SMC by at least an order of magnitude, setting a preferred direction for coherent, vertical low-amplitude displacements, while the disk asymmetry drives in-plane offsets. Projecting onto the observed LMC frame, the mean of our predicted SMBH probability distribution is located at $(\alpha,\delta)=(80.23^{\circ},-69.55^{\circ})$, with a $1\sigma$ confidence ellipse having semi-major and semi-minor axes of $(a,b)=(1.34^{\circ},0.56^{\circ})$, respectively. This mean is $\sim6$ arcminutes north of the adopted dynamical center, while the mode coincides with the dynamical center and lies well within the $1\sigma$ confidence region. Furthermore, all literature estimates of the LMC center considered here fall within the $2\sigma$ confidence region. This provides a concrete, testable target for ongoing and upcoming spectroscopic surveys, transforming the search for the LMC SMBH from an unconstrained problem into a focused observational strategy.
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All authors Robin Chisholm, Elena D'Onghia, Niv Drory, Andrew Fox, Noam Libeskind
Astrophysics of Galaxies · Cross-listed from astro-ph.HE
Optical Spectroscopy of a Candidate O-Star X-ray Binary in M33
Margaret Lazzarini, Lara Cullinane, Karoline Gilbert et al. (+8 more)
We present new observations of a candidate O-type donor
star in a high mass X-ray binary (HMXB) in M33. The candidate donor
star is spatially coincident with a hard X-ray point source. The
star's optical magnitude and colors are consistent with what is expected for a massive
star. The four band optical/UV spectral energy distribution (SED) of the donor
star is well fit by an O-giant model with an effective temperature of $\sim$43 kK, mass of 75$_{+9}^{-0.3}$ $M_{\odot}$, and surface
gravity of log(g) of $\sim$3.8. We present four epochs of optical spectroscopy of the donor
star taken with the Keck/DEIMOS spectrograph over the course of approximately one year. Features in the
star's spectrum are consistent with an O-type
star. The
star's spectrum exhibits a strong H$\alpha$ emission line during all epochs of observation with a variable line profile. We measure the
star's radial velocity for each epoch, which we use to fit for a systemic velocity. We find that the systemic velocity is offset from the local gas velocity from HI measurements, suggesting that the system has a peculiar velocity relative to the local gas. We observe a radial velocity shift in the He I absorption lines that is consistent with motion within a binary system.
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All authors Margaret Lazzarini, Lara Cullinane, Karoline Gilbert, Puragra GuhaThakurta, Kyros Hinton, Daniel Stern, O. Grace Telford, Tobin M. Wainer, Benjamin F. Williams, Robert Alexander, Ernesto Ramirez Jr
Astrophysics of Galaxies · Cross-listed from astro-ph.HE
Jet Feedback and the Self-Regulated Growth of Black Holes Embedded in AGN Disks
Marguerite Epstein-Martin, Kung-Yi Su, Zoltan Haiman et al. (+1 more)
Accretion disks in active galactic
nuclei (AGN) are expected to host embedded stellar-mass black holes (BHs) whose gas capture rates can be highly super-Eddington. Without feedback, they would rapidly grow and deplete the disk, but at such high feeding rates, radiation is advected inward with the flow. We test whether the resulting
accretion-powered jet and its shocked cocoon can (i) self-regulate the BH's growth rate and (ii) break out of the AGN disk. Using GIZMO, we perform three-dimensional simulations of a $10\,{\rm M}_\odot$ BH, embedded in dense AGN-disk gas, launching a particle-spawned jet whose mass flux scales with the
accretion rate. We explore a range of jet velocities, ambient temperatures and densities, and three cooling regimes. We find that the jet-inflated cocoon stalls near the Bondi radius and maintains a modest aspect ratio and the self-regulated mass flux is determined by momentum balance at the Bondi radius. Cooling controls the mode of self-regulated
accretion, from large-amplitude oscillation cycles at low
metallicity to weak, quasi-steady modulation at solar
metallicity. Scaling our results to outer disk conditions implies that mechanical feedback limits BH growth to within an order of magnitude of the Eddington rate – largely preventing the overgrowth problem. Over the same disk region, the cocoon remains confined within the disk. In the inner disk,
accretion onto the embedded BHs is limited by tidal shear rather than the Bondi radius, and our simulations no longer apply. Whether runaway growth and cocoon breakout remains possible in these inner regions needs further study.
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All authors Marguerite Epstein-Martin, Kung-Yi Su, Zoltan Haiman, Rosalba Perna
Astrophysics of Galaxies
Population III Host Candidates at $z\sim2$: Strong He II $\lambda1640$ and Absent UV Metal Lines in HETDEX Ly$\alpha$ Emitters
Mahan Mirza Khanlari, Dustin Davis, Karl Gebhardt et al. (+15 more)
Population III (Pop III)
stars are expected to produce extremely hard ionizing spectra, yet direct evidence for their signature–strong narrow He II $\lambda1640$ emission with weak or absent metal lines–remains elusive. Although Pop III formation peaks at $z\gtrsim10$, models predict that nearly pristine gas pockets can survive to later times, making intermediate-
redshift searches a probe of metal mixing across
cosmic time. We search 109,545 high-confidence Ly$\alpha$-emitting
galaxies at $1.9<z<2.3$ in the Hobby–Eberly
Telescope Dark Energy Experiment's database for systems with strong He II $\lambda1640$ and no detected UV metal lines, recovering eight candidates and a first-order, tentative comoving number density of $\sim30$ Gpc$^{-3}$. The eight-object stack yields a rest-frame He II equivalent width of $28.7\pm6.7$ Angstrom, He II/Ly$\alpha=0.354\pm0.094$, and a resolution-corrected He II FWHM of $449\pm105$ km s$^{-1}$. We find no significant N V, C IV, or O III] emission; using the He II width to set the scale, we derive $3\sigma$ upper limits of N V/He II $<0.167$, C IV/He II $<0.128$, and O III]/He II $<0.140$. This combination of strong He II, elevated He II/Ly$\alpha$, moderate line width, and weak metal lines is difficult to reproduce with metal-enriched stellar populations, AGN narrow-line regions, shocks, or classical Wolf–Rayet features. We interpret the sample as candidates for very metal-poor or Pop III-like ionizing sources at $z\sim2$. Definitive confirmation requires deeper rest-UV spectroscopy to measure He II and metal-line limits in individual objects, followed by rest-optical spectroscopy of H$\beta$, [O III] $\lambda4959,\lambda5007$, [O II] $\lambda3727$, and H$\alpha$ to constrain gas-phase
metallicity, ionization conditions, and AGN activity.
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All authors Mahan Mirza Khanlari, Dustin Davis, Karl Gebhardt, Tiger Yu-Yang Hsiao, Julian B. Muñoz, Alessandra Venditti, Erin Mentuch Cooper, Robin Ciardullo, Olivia Curtis, Daniel J. Farrow, Steven L. Finkelstein, Caryl Gronwall, Gary J. Hill, Wolfram Kollatschny, Chenxu Liu, Shiro Mukae, Shun Saito, Donald P. Schneider
Astrophysics of Galaxies · Cross-listed from astro-ph.CO
A Dark-matter Origin of Little Red Dots: Early Seeding and Super-Bondi Accretion
Hua-Peng Gu, Fangzhou Jiang, Xian Chen et al. (+2 more)
The "Little red dots" (LRDs) are a population of accreting supermassive black holes (SMBHs) in the early Universe which often exhibit undermassive or even undetectable stellar hosts. Their early emergence, high space density, and extremely large black-hole-to-stellar mass ratios pose a serious challenge to conventional seeding scenarios that rely on baryon for both the formation and growth of black holes. Here we demonstrate that the above anomalies can be naturally resolved if dark matter is self-interacting. We apply a fully relativistic, non-
equilibrium halo-
evolution model, first developed in our earlier work, to trace the complete gravothermal
evolution of self-interacting dark matter (SIDM)
halos, from the initial collapse into BH seeds to the subsequent
accretion of dark matter. We find that in highly concentrated
halos assembled before reionization, gravothermal collapse efficiently produces stellar-mass black-hole seeds within a few hundred million years. Remarkably, and contrary to standard expectations for dark-matter
accretion, heat conduction in SIDM then sustains a prolonged super-Bondi inflow that drives these seeds to supermassive scale by the LRD epoch, without baryonic assistance. The
halo conditions required for completing these processes, together with the probability of avoiding major mergers that disrupt gravothermal
evolution, result in an SMBH population consistent with the observed abundance and
redshift distribution of LRDs. Our findings establish a pathway in which SMBHs are seeded and assembled primarily from dark matter, well before substantial
galaxies form around them, thereby offering both a compelling physical explanation for LRDs and a new observational probe of dark-matter microphysics.
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All authors Hua-Peng Gu, Fangzhou Jiang, Xian Chen, Ran Li, Zi-Xiang Jia
Astrophysics of Galaxies · Cross-listed from astro-ph.HE
A Standard Ultraviolet Continuum Can Hide Supercritical Accretion in GN-z11
Samik Mitra and Ramananda Santra
The ultraviolet continuum from a high-
redshift accreting black hole is routinely used to infer its mass. GN-z11 offers a sharp test of whether that inference is secure. A thin-disk fit to its continuum gives an Eddington mass of $M_{\rm E}=1.12\times10^{7}\,\Msun$, an order of magnitude above the $\log(\Mbh/\Msun)=6.2\pm0.3$ inferred from broad N~iv. We show that this apparent tension is not imposed by the ultraviolet slope alone. We derive a closed-form criterion comparing the radius where observed
photons are produced with the radius where a supercritical flow departs from efficient solution. For GN-z11, the criterion places the supercritical transition inside the ultraviolet-emitting region. Composite disks retaining the outer solution confirm this numerically, requiring $\Mdot_{\rm out}=3.1$–$4.4\,\Msun\,\mathrm{yr^{-1}}$ and placing $\Rsph=(1.2$–$1.8)\times10^{3}\,\rg$ inside $\Ruv=(2.6$–$2.9)\times10^{3}\,\rg$. Replacing the inner $\sim10^{3}\rg$ by a supercritical flow shifts the fitted slope by only $\Delta\betaUV=+0.08$ to $+0.11$, comparable to uncertainties from standard spectral modelling. Reversing the radial ordering requires the effective transition to move outward by a factor $1.7$–$2.1$. Within our composite models, the measured slope constrains black-hole mass only to around $10^{6}\,\Msun$, an order of magnitude below the continuum Eddington mass. Continuum Eddington masses should therefore be treated as model-dependent bounds that assume global thin-disk efficiency. The same hierarchy appears in three additional JWST sources under the disk-dominated interpretation, where separation masses are only $4$–$6$% of continuum Eddington masses. This distinction can substantially weaken the seed-mass and early-growth demands inferred from ultraviolet continua at
cosmic dawn for the first massive black holes.
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Astrophysics of Galaxies · Cross-listed from astro-ph.HE
Can Isotropic Thermal Conduction Heat One of the Hottest Cool Cores?
Samik Mitra, Ramananda Santra and Norbert Werner
Thermal conduction can act as a heating mechanism for cool-core clusters, yet the same transport must erode any temperature discontinuity it crosses. Ophiuchus permits both effects to be tested in the same atmosphere. Its temperature rises from about $1$ keV in the innermost core to $9$ keV at $r\sim30$ kpc, making conductive heating especially favorable, while two sharply resolved cold fronts independently constrain the same transport. \textcolor{black}{We construct a steady radial energy balance from deprojected Chandra density and temperature profiles, with XRISM-based limits on turbulent heating and a subsonic inflow contribution.} Closing the balance with conduction requires only sub-Spitzer coefficients — \Ftwentyfive\ at 25 kpc and \Finner\ and \Fouter\ at the inner and outer cold fronts — so conduction can energetically supply the missing heat. Yet the same coefficients, applied normal to the cold-front surfaces, would broaden the fronts to their observed width limits within \Tinner\ and \Touter\ Myr, short compared to the characteristic sloshing timescales that generate and sustain such interfaces. For a representative 200 Myr residence time, the radial conductivity demanded by the energy balance exceeds the cross-front conductivity permitted by front survival by roughly a factor of three, with the required anisotropy exceeding unity in 99.9% and 98.8% of accepted models. The result leaves two broad regimes. Thermal conduction is either subdominant in Ophiuchus or contributes substantially but is strongly anisotropic, with heat transport suppressed across the cold fronts relative to the radial direction. Together they disfavor locally isotropic conduction as a dominant heating mechanism in cool cores generally.
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Astrophysics of Galaxies · Cross-listed from astro-ph.IM
Disentangling 3D Magnetic Field Geometry from Turbulence: A Polarization-Based Classification Method
Sophia Kressy and Fabian Heitsch
We develop a decision tree classifier that recovers 3D
magnetic field geometry from synthetic polarization and position angle maps of a magnetized, turbulent field. We test the classifier for a series of geometries: Uniform, Wavy, Helical, and Hourglass. The classifier is calibrated across a range of Alfvénic Mach numbers and injected Stokes Q,U noise levels for each geometry. Our models show the median and skewness of the polarization fraction, as well as the position angle circular variance, vary systematically with both geometry and the Alfvénic Mach number. We find that the 3D geometry can be isolated by using a variety of polarization and position angle metrics to break degeneracies. The classifier recovers most geometries well for sub-Alfvénic cases (Alfvénic Mach Number < 1). For Alfvénic Mach Number > 1, polarization and position angle statistics converge across all geometries and the classifier fails to recover the
magnetic field structure.
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Astrophysics of Galaxies
Common Excitation Patterns of Star Formation, Active Galactic Nuclei, and Shocks in Seyfert Galaxies
Peixin Zhu, Lisa J. Kewley, Dominika Ł. Król et al. (+6 more)
The growth of
galaxies and their central supermassive black holes is closely connected, yet the net effect of active galactic
nuclei (AGN) feedback on host-
galaxy star formation remains uncertain. AGN may enhance, suppress, or have little measurable impact on
star formation, but distinguishing among these outcomes requires separating
star-formation and AGN photoionization from shock excitation, which is expected in AGN-driven outflows but has been difficult to isolate. Here we apply a recently developed theoretical three-dimensional diagnostic diagram, designed to separate
star formation, AGN, and shock excitation, to VLT/MUSE IFU observations of nine nearby (z < 0.026) Type 2 Seyfert
galaxies. We find a common excitation pattern across the sample:
star-forming rings or arcs at projected radii of r~0.8-6 kpc, AGN-photoionized bicones extending to kpc scales, central fast-shock-dominated regions that often extend perpendicular to the AGN bicone, and pure-shock- dominated regions surrounding the central fast shocks and appearing locally within the
star-forming rings. Deep Chandra X-ray morphology independently supports this decomposition. The circumnuclear
star-forming rings are consistent with bar-driven resonances, although positive AGN feedback may also contribute. The central fast shocks are broadly consistent with AGN jet-ISM interactions, while AGN wind-ISM interactions may also play an important role in
galaxies with low-power jets. These results establish central shocks as a common feature of Seyfert
galaxies and demonstrate the importance of accounting for shock excitation in AGN feedback studies.
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All authors Peixin Zhu, Lisa J. Kewley, Dominika Ł. Król, Giuseppina Fabbiano, Lars Hernquist, Ralph S. Sutherland, Anna Trindade Falcão, Martin Elvis, Riccardo Middei
Astrophysics of Galaxies · Cross-listed from astro-ph.SR
The JWST Proto-PAH Project: Detection of the methyl radical CH$_{3}$ in the highly evolved C-rich object SMP LMC 011
Jialu Li, D. A. García-Hernández, A. Manchado et al. (+17 more)
We report the first detection of the neutral methyl radical CH$_3$ in a highly evolved C-rich object, SMP LMC 011, using JWST MIRI/MRS. CH$_3$ is well fitted by an excitation temperature of $T_{\rm ex} \simeq$~190\,K and a column density of $N_{\rm tot}(\mathrm{CH_3}) \simeq 5.6\times10^{17}$ cm$^{-2}$. We also report the non-detection of ethane (C$_2$H$_6$), consistent with CH$_3$ reacting preferentially with unsaturated radicals rather than self-recombination, which may be inefficient in SMP LMC 011. Combined with the exceptionally large benzene column density of SMP LMC 011, this supports a methyl-addition route from benzene towards alkyl-substituted aromatics. We propose that the high CH$_3$ abundance is driven by the erosion of hydrogenated amorphous carbon (HAC) dust grains in the dense warm
torus by UV
photons from the central
star and/or by shocks, which release CH$_3$ directly into the gas phase. These results establish CH$_3$ as a key reactive intermediate in the formation of complex hydrocarbons in C-rich circumstellar environments. Chemical models that incorporate methyl-addition reactions are needed for a better understanding of PAH formation pathways in evolved
stars. The potential detection of alkyl-substituted aromatics such as toluene (C$_7$H$_8$) and ethylbenzene (C$_8$H$_{10}$) in C-rich evolved
stars would provide direct confirmation of CH$_3$-driven aromatic growth in circumstellar environments.
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All authors Jialu Li, D. A. García-Hernández, A. Manchado, Debayan Das, J. Cami, Els Peeters, G. C. Sloan, B. Aringer, J. Bernard-Salas, C. Bhatt, Nicholas Clark, Harriet L. Dinerstein, M. A. Gómez-Muñoz, Kathleen E. Kraemer, M. Matsuura, R. Sahai, N. C. Sterling, Kevin Volk, G. M. Wahlgren, A. A. Zijlstra
Astrophysics of Galaxies
Rubin Observatory Reveals a Dust-Shrouded Halo Globular Cluster in Ophiuchus
Aashay Pai, William Cerny, Andrew B. Pace et al. (+9 more)
We present the discovery of the Milky Way satellite Rubin-GC1 (Rubin J1628-1735) using data from the NSF-DOE Vera C. Rubin Observatory's Early Data Preview 2. The system was discovered in the direction of the Galactic bulge with $(l, b) \sim (359^{\circ}, 21^{\circ})$ in a region of high stellar density and a foreground reddening of $E(B-V) \approx 0.7$. We simultaneously fit the morphology and isochrone parameters of Rubin-GC1, determining that it is a faint ($M_V = -2.4^{+0.5}_{-0.7}$) and compact ($r_{1/2} = 5^{+1}_{-1}$ pc) Milky Way satellite at a distance of $D_\odot = 31^{+3}_{-3}$ kpc; its stellar population is intermediate-age ($\tau=9.2^{+1.2}_{-0.7}$ Gyr) and moderately metal-rich ($\mathrm{[Fe/H]_{iso}}=-0.73^{+0.04}_{-0.04}$). Together, these properties suggest Rubin-GC1 is most likely a
star cluster in the faint tail of the luminosity function of globular clusters surrounding the Milky Way. We identify a distinct proper motion signature from Rubin-GC1 in Gaia DR3, and from a comparison of the system's 5D phase space information to $N$-body models of the Sagittarius dwarf spheroidal
galaxy's tidal stream, we determine that Rubin-GC1 is likely an accreted cluster associated with the Sagittarius leading arm. The discovery of Rubin-GC1 highlights the potential of Rubin to uncover faint, resolved satellites in dust-shrouded regions of the Milky Way, including remnants of the
accretion events that have shaped the
Galaxy's hierarchical assembly.
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All authors Aashay Pai, William Cerny, Andrew B. Pace, Alex Drlica-Wagner, Peter S. Ferguson, Marla Geha, Chin Yi Tan, Sasha N. Campana, Burçin Mutlu-Pakdil, Alexander H. Riley, Nora Shipp, Guy S. Stringfellow
Astrophysics of Galaxies · Cross-listed from astro-ph.CO
Using the Circumgalactic Medium of Dwarf Galaxies as a Calorimetric Dark Matter Detector
Abby Mintz, Digvijay Wadekar and Romain Teyssier
Many well-motivated dark matter (DM) scenarios, including dark
photon DM,
axion-like particles, sterile
neutrinos, and primordial black holes, can deposit energy into ordinary matter and significantly raise the thermal energy of astrophysical gas. We present a simple, model-independent implementation of DM-induced heating in the RAMSES hydrodynamic simulation code, parameterized by an effective local heat-transfer rate $\Gamma_{\rm heat}$. Using simulations of an isolated gas-rich dwarf
galaxy with properties similar to WLM, we find that DM heating substantially alters the thermal structure of the circumgalactic medium (CGM) while leaving the
star formation rate and the dense ISM nearly unchanged. For $\Gamma_{\rm heat} = 10^{-27}$ to $10^{-25}\ {\rm s}^{-1}$, the neutral hydrogen column at 10 kpc is suppressed by 0.6 to 3.9 dex relative to the control simulation. Similarly, the C II and Si II column densities decrease by 4.1 and 5.5 dex, and by 2.2 and 3.0 dex for C IV and Si IV. These signatures are accessible to
quasar absorption-line spectroscopy, so CGM observations of nearby field dwarf
galaxies provide a promising avenue for constraining dark matter models that inject heat into ordinary matter.
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Astrophysics of Galaxies
Constraining the Delay Time Distribution of the r- and s-Process from Stellar Ages at Solar Metallicity
Meng Zhang and Hans-Walter Rix
We present a new approach to constraining the delay time distribution (DTD) governing r- and s-process element production. Rather than using
metallicity as a proxy for time, we work directly with stellar ages at solar
metallicity, where chemical
equilibrium models are most applicable. We analyze two complementary samples: more than $10,000$ red clump (RC) thin disk
stars at solar
metallicity from LAMOST, and solar twins with high-precision abundances; both have well-determined stellar ages $\tau$. We fit chemical-
equilibrium models with power-law DTDs to the
evolution of [Eu/Mg]$(\tau)$ and [Ba/Mg]$(\tau)$ in each sample, taking europium as a canonical r-process element and barium as an s-process element, each referenced to magnesium as a near-instantaneous, CCSNe-dominated element. To validate the method, we first apply it to [Fe/Mg]$(\tau)$ and recover that $\approx\!70\%$ of Fe comes from a delayed channel with a declining DTD $\propto t^{-1.2}$, in agreement with well-established results for iron production in thermonuclear
supernovae. It also shows that about $60\%$ of Eu and Ba forming today originate from strongly-delayed processes, and the inferred delayed-production rates of both Eu and Ba rise with delay time, opposite to that of thermonuclear
supernovae. These results provide direct temporal constraints on r- and s-process enrichment, complementary to
metallicity-based chemical-
evolution studies. Because we model abundance referenced to Mg, and the same trend is recovered across
stars of different guiding-center radii, this appears unaffected by radial migration and chemical
evolution varying with Galactocentric radius. If confirmed, it points to delayed
neutron-capture production beyond NS–NS mergers.
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Astrophysics of Galaxies
The Multiphase CGM in the Epoch of Reionization: CII and CIV absorbers around [OIII] Emitters
C. Piscitelli, V. D'Odorico, M. Galbiati et al. (+17 more)
We investigate the multiphase circumgalactic medium (CGM) during the Epoch of Reionization (EoR, $z>6$) by cross-correlating cool- CII and warm-ionized CIV absorption systems with
star-forming [OIII] emitters. JWST/NIRCam wide-field slitless spectroscopy from the EIGER survey is combined with medium- and high-resolution optical/NIR spectra of six background
quasars, including new VLT/X-Shooter observations of PSO J159-02. We analyze the relation between 16 CII and 14 CIV absorbers ($\log(N) > 13.0$) and 136
galaxies, within an impact parameter of R$_{\perp} \leq$ 1000 pkpc and a line-of-sight separation of $\Delta v \leq 500$ km/s. We detect a statistically significant excess of both ions around
galaxies compared to a randomized background. We observe that the CIV covering fraction remains enhanced up to $\sim 1$ pMpc, whereas CII drops to the background level beyond $\sim 0.5$ pMpc, demonstrating that the warm-ionized phase is more spatially extended than cooler gas. Jointly, the 3D
galaxy-absorber spatial clustering is significantly weaker than the
galaxy-
galaxy auto-correlation. This provides direct physical evidence that early carbon enrichment is not confined to the virial radius of massive
star-forming systems; rather, a substantial fraction of these metals permeates the diffuse intergalactic medium (IGM) or is injected by a widespread population of faint, undetected dwarf
galaxies. Finally, we note a rapid radial decline of the CIV covering fraction compared with lower
redshift samples at $z<2$ and $z\sim3-4$ pointing out an evolving CGM ionization structure where early metals reside predominantly in lower ionization states. In conclusion, we determine a conservative lower limit for the observed carbon mass of $\rm M_{CII + CIV} \geq 2.8 \times 10^6 \, M_{\odot}$ within 300 pkpc.
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All authors C. Piscitelli, V. D'Odorico, M. Galbiati, M. Bischetti, G. Cupani, R. Dutta, S. Cantalupo, S. Di Stefano, S.T. Guida, K. Knudsen, C. Mazzucchelli, L. Paquereau, L. Pentericci, R. Rana, F. Ricci, F. Salvestrini, A. Tortosa, A. Travascio, C. Vignali, L. Zappacosta
Astrophysics of Galaxies · Cross-listed from astro-ph.CO
Anisotropic redshift distributions in photometric galaxy clustering and their cosmological impact
Zekang Zhang, Yunhe Wang, Daniel Gruen et al. (+4 more)
Photometric
galaxy clustering is a major probe of large-scale structure whose interpretation relies on accurate characterization of the
galaxy redshift distribution, $n(z)$. Standard analyses assume the $n(z)$ of a selected lens sample to be isotropic, whereas observational systematics can imprint spatial variations. We quantify how this anisotropy biases angular
galaxy clustering, internal consistency, and cosmological inference. We develop an analytical formalism for clustering under spatially varying $n(z)$ and forward-model realistic observational systematics,
galaxy selection, and tomographic binning. For a fiducial magnitude-limited sample, modeling $w(\theta)$ with a single global $\bar n(z)$ underestimates the clustering signal by up to $\sim10\%$ at small scales in the highest-
redshift bin, decreasing towards lower
redshift. In a $2\times2$pt analysis, cosmological parameter shifts remain below $1\sigma$ for KiDS-like and DES-like setups. For an LSST-like setup retaining KiDS-like selection and observing-condition variation, $\sigma_8$ is biased low by $1.7\sigma$ and $\Omega_m$ high by $1.4\sigma$, while the high-
redshift galaxy bias shifts by up to $\sim4\sigma$. The anisotropy also affects whether the probes are consistent enough to combine: a calibrated posterior-predictive internal-consistency test finds the contaminated angular clustering improbable given the joint
cosmic-shear and
galaxy–
galaxy-
lensing constraints (median calibrated $\tilde p\approx8\times10^{-4}$ under LSST-like noise). Anisotropic
redshift distributions are therefore a potentially significant systematic for future photometric clustering analyses. Our forward model can be used to mitigate it given a realistic selection function and
galaxy population model.
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All authors Zekang Zhang, Yunhe Wang, Daniel Gruen, Hui Kong, Luca Tortorelli, Silvan Fischbacher, Ziang Yan
Astrophysics of Galaxies
ALMA-JELLY II. Constraining the radial profiles of the quenching timescales in ram-pressure-stripped galaxies
Roberto P. Infurna, Matteo Fossati, Alessandro Boselli et al. (+21 more)
We investigate the environmental quenching histories and spatial progression of ram-pressure stripping in 11
galaxies in the nearby Coma, Norma, and A1367 clusters. As part of the ALMA-JELLY large program, we combine high-sensitivity VLT/MUSE integral-field spectroscopy with ultraviolet-to-far-infrared photometry in 37 spatially resolved disc apertures. The sample spans $\log(M_*/\mathrm{M}\odot)\sim7.5-10.5$ and includes
galaxies undergoing active or recent ram-pressure stripping, identified through prominent H$\alpha$ or UV tails. We use
Bayesian spectrophotometric modelling with exponentially declining
star-formation histories and show with mock data that combining spectra and photometry breaks parameter degeneracies and improves quenching-age constraints. All
galaxies show quenched outer discs and relatively old ($\lesssim1$ Gyr) stellar populations. Massive
galaxies ($\log(M_*/\mathrm{M}_\odot)>9.5$) exhibit clear outside-in quenching: inner regions quench about 500 Myr later than their outskirts. The small scatter in quenching age with distance from the truncation radius, despite differences in environment and stripping geometry, points to a common evolutionary sequence. Low-mass and dwarf
galaxies instead show weak radial gradients, with quenching occurring more rapidly, typically within 300 Myr.
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All authors Roberto P. Infurna, Matteo Fossati, Alessandro Boselli, Michele Fumagalli, Jeffrey D.P. Kenney, Pavel Jáchym, Ming Sun, Elias Brinks, Françoise Combes, Patricia da Silva, Romana Grossová, Stephen Gwyn, Kokoro Hosogi, Alessandro Ignesti, Jin Koda, Jan Palouš, Nathanael Pichette, Sujith Ranasinghe, Tom C. Scott, Harrison J. Souchereau, Juhi Tiwari, Bernd Vollmer, Norbert Werner, Masafumi Yagi
Astrophysics of Galaxies · Cross-listed from astro-ph.HE
The effect of pressure confinement on the maximum mass of rapidly accreting supermassive stars
Lorenz Zwick, Christopher Tiede and Zoltán Haiman
We derive an extension of Chandrasekhar's pulsational stability criterion for relativistic
stars with a pressure boundary condition at the surface. We then apply the new criterion to hylotropes, a model describing rapidly accreting supermassive
stars with a core-envelope structure. We find that confinement typically stabilises
stars, delaying the onset of the general relativistic instability when the external pressure at the surface is roughly $\sim10^{-3}$ of the
stars' hydrostatic pressure scale. Beyond this value, the critical mass at marginal stability increases rapidly, exceeding the value of $\sim 10^5$ M$_{\odot}$ for helium burning, isolated $n=3$ polytropes by orders of magnitude. We discuss how the required pressure boundary conditions may be produced by the combined ram and
magnetic pressure supplied by the
accretion flow as it assembles the supermassive
star, and provide a fitting formula for the final mass before collapse. As a rough estimate assuming equipartition between
magnetic and thermal pressures in a standard $\alpha$-disk, we find that the critical mass doubles at
accretion rates of order $\dot M\sim100\,{\rm M_\odot}\,{\rm yr}^{-1}$, again increasing rapidly after this value. Our results show under what conditions, potentially realized in a subset of high
redshift halos, non-rotating SMS may collapse into black holes beyond the typical scale of heavy seeds.
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Astrophysics of Galaxies · Cross-listed from astro-ph.CO
Assembly Bias in eRASS1 X-ray Galaxy Clusters: Accounting for Non-uniform Survey Exposure
Jitendra Joshi, Divya Rana and Surhud More
Halo assembly bias describes the dependence of
halo clustering on properties beyond
halo mass and provides a means of connecting
halo assembly history to the large-scale matter distribution. We develop and test a relative clustering methodology for measuring differences in the large-scale bias of two
halo populations using the ratio of their cluster–
galaxy pair counts. In the linear regime, this ratio can be related to the difference in cluster bias, while the
galaxy autocorrelation independently constrains the
galaxy bias. We apply the method to a volume-limited X-ray selected
galaxy clusters from the eROSITA eRASS1 catalogue, dividing them into high- and low-temperature subsamples with matched distributions in X-ray luminosity,
redshift, and exposure. We first verify the validity of the linear approximation, finding $\xi(r)\ll1.0$ over $4$–$10\,h^{-1}\mathrm{Mpc}$. The joint clustering analysis yields $b_{\rm g}=1.610^{+0.018}_{-0.019}$ and a bias difference $\Delta b=0.8\pm1.1$. DES Y3 weak gravitational
lensing measurements provide an independent test of the
halo masses, yielding $\log(M_{200\mathrm{m}}/h^{-1}M_\odot)=14.33^{+0.07}_{-0.07}$ and $14.33^{+0.10}_{-0.09}$ for the high- and low-temperature samples, respectively, with a mass difference of $\Delta\log M_{200\mathrm{m}}=-0.01\pm0.12$. We therefore find no statistically significant evidence for assembly bias at the $1\sigma$ level, but our measurement is consistent with the bias difference measured for analogous
halo populations in the FLAMINGO simulation. The result therefore does not rule out assembly bias at the level expected from the simulation, while demonstrating that the relative clustering methodology provides a framework for future assembly-bias measurements with larger X-ray cluster and
galaxy surveys.
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Astrophysics of Galaxies
Highly Ionized Oxygen in the Circumgalactic Medium of TNG100 Galaxies: Distributions, Thermal States, and Ionization Mechanisms
Yossi Oren, Amiel Sternberg, Christopher F. McKee et al. (+1 more)
We investigate the origin of the highly ionized oxygen species, O VI, O VII, and O VIII, in the circumgalactic medium (CGM) of
galaxies at
redshifts $z \approx 0$, by post-processing the outputs of the Illustris TNG100 simulation alongside analytic modeling. Our computations are broadly consistent with observations, and we provide convenient functional fits for the predicted mean oxygen ion column densities as functions of
halo virial mass. We determine the relative roles of electron impact collisional ionization versus photoionization by the metagalactic radiation field in producing the ions for
halo masses ranging from $10^{10.5}$ to $10^{14.5}$~M$_\odot$. We also determine the thermal gas phases, virialized hot, intermediate temperature, or cool, within which the ions reside. If the
halo virial temperature is below the gas temperature at which the ion fractions are maximal for collisional ionization
equilibrium (CIE), then photoionization dominates the overall CGM ion mass and column density. When photoionization dominates, the ions are produced primarily in the shock heated virialized phase. If the virial temperature is above the gas temperatures at which the ion fractions are maximal for CIE, then collisions dominate the ionization. However, if the virial temperature is much larger than the ion CIE peak temperature a substantial portion of the ion mass may reside within the intermediate temperature phase as opposed to the hot virialized gas. For MW-mass
halos, the O VI and O VII are produced collisionally, and the O VIII by photoionization, all three in the hot, virialized phase.
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All authors Yossi Oren, Amiel Sternberg, Christopher F. McKee, Yakov Faerman
Astrophysics of Galaxies
The WISSH quasars project XIII. A multi-epoch study of ultra-fast broad absorption line outflows at cosmic noon
A. Deconto-Machado, G. Vietri, E. Piconcelli et al. (+22 more)
Ultra-fast broad absorption line outflows (uBAL, ~0.1-0.2c) represent some of the most extreme manifestations of
quasar-driven winds. We aim to investigate the variability of uBALs through their characterisation across different epochs and multiple ionic species. The main goal is to constrain their physical properties, locations, and kinetic powers to evaluate their potential impact on the respective
quasar host
galaxies. We performed a multi-epoch analysis of three hyper-luminous
quasars from the WISSH sample, namely WISSH53, WISSH56, and WISSH71, at
redshifts z=3.628, 4.101, and 3.567, respectively. New and archival spectra, spanning up to ~23 years of monitoring in the observed frame, were used in the analysis. We modeled absorption associated with the CIV transition with Gaussian components, accounting for covering factor variations. A conservative analysis of multi-ion profiles (PV, Lyalpha, NV, SiIV) was also performed, considering the same uBAL velocity as CIV. We derived ionic column density, as well as ionisation parameters, which allowed us to estimate lower and upper limits on distances and kinetic powers of the outflows. The CIV uBALs in the three sources exhibit velocities up to ~0.2c and show significant variability across epochs, likely driven by changes in ionisation state and/or transverse gas motion. The analysis of the multiple troughs highlights the dominant mechanisms causing variability and enables the derivation of robust lower and upper limits of the physical and energetic properties of the outflows. Outflow distances are constrained from the broad line region (BLR) radius (~1 pc) up to a few hundred parsecs, and kinetic powers of individual troughs reach up to ~25% of the
quasar bolometric luminosity, in the most extreme cases. Our results demonstrate that extreme outflows such as the uBALs are able to inject sufficient kinetic energy to affect the host medium.
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All authors A. Deconto-Machado, G. Vietri, E. Piconcelli, S. Bisogni, T. Misawa, A. Gargiulo, G. Lanzuisi, A. Travascio, M. Bischetti, L. Zappacosta, E. Bertola, G. Cresci, F. la Franca, M. Gaspari, F. Salvestrini, C. Vignali, A. Luminari, E. Marini, F. Tombesi, A. Bongiorno, S. Carniani, C. Feruglio, F. Fiore, E. Glikman, V. Testa
Astrophysics of Galaxies · Cross-listed from astro-ph.SR
A new method to cleanly separate hot and cool populations using just Gaia and 2MASS photometry
J. Maíz Apellániz and M. Pantaleoni González
We have developed a photometric method that produces clean hot (intrinsically blue) populations using Gaia and 2MASS photometry alone with [a] a very small (false positives < 1%) contamination from cool (intrinsically red) luminous sources, [b] independent of extinction (limited only by S/N), and [c] with only small losses (false negatives < 10%) of real OB
stars. Applying the method to Gaia DR3 data we are able to recover extinguished OB
stars down to E(G_BP-G_RP) = 5, producing a catalog of ~2x10^5 candidate OB
stars that reaches beyond the Scutum-Centaurus arm. This method can potentially extend the sample of known OB
stars by an order of magnitude, which would yield a large leap in our knowledge of the populations of compact-object progenitors, including gravitational-wave sources.
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