Astrophysics of Galaxies · Cross-listed from gr-qc
Exact black hole solutions with semi-symmetric vectorial torsion
Lehel Csillag and Tiberiu Harko
Semi-Symmetric metric
gravity extends general relativity by introducing a semi-symmetric connection with vectorial torsion. The modified field equations contain extra contributions from the torsion vector and its derivatives. Assuming a purely radial torsion vector consistent with spherical
symmetry, we derive two exact
vacuum solutions. The metric depends on two integration constants, defining the Schwarzschild radius and a new cosmological-type length scale. Classical Solar System tests, including perihelion precession, light deflection, and radar echo delay, are used to constrain the new length scale and the associated deviations from general relativity. The thermodynamic properties of the resulting black hole solutions are investigated, and it is shown that the vector perturbation sector is linearly stable.
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Astrophysics of Galaxies · Cross-listed from astro-ph.HE
The X-Ray Continuum Emission Region in the Lensed Quasar SDSS J133907.23+131038.6 is Much Smaller than the Accretion Disk
Christopher W. Morgan, James B. Margeson, Gilberto Garcia et al. (+4 more)
We analyze microlensing variability in 15 seasons of optical monitoring data and 4 epochs of new X-ray observations of the doubly-imaged gravitationally lensed
quasar SDSS J133907.23+131038.6 to place empirical constraints on the size and structure of that system's X-ray and optical continuum emission regions. Employing a
Bayesian Monte Carlo method, we analyzed ground-based optical light curves to constrain the half-light radius of the far-UV source $\log(r_{\rm 1/2, FUV}/{\rm cm})=15.78^{+0.26}_{-0.28}$ at 193 nm, the rest-frame center of the r-band, assuming a $60^\circ$ inclination angle. This size corresponds to $\sim100\,{\it r}_{\rm g}$ for a $4.0 \times 10^{8} \: {\rm M_{\odot}}$ black hole. We measured the half-light radius of the full band ($0.2-8.0 \: {\rm keV}$) X-ray continuum emission region $\log(r_{\rm 1/2, X_{full}}/{\rm cm})=14.32^{+0.23}_{-0.31}$, a size measurement that is consistent with the radius of the innermost stable circular orbit (ISCO) in the Schwarzschild metric.Two shifted Fe K$\alpha$ lines caused by microlensing are detected in the stacked spectrum of image A at 5.9 and 8.9~keV at $>99\%$ significance.
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All authors Christopher W. Morgan, James B. Margeson, Gilberto Garcia, Xinyu Dai, Luis J. Goicoechea, Vyacheslav N. Shalyapin, George Chartas
Astrophysics of Galaxies
Measuring Simulated Circumgalactic Medium Turbulence with Emission-Weighted Projected Velocity Structure Functions in FOGGIE
Helena Bouchereau, Cassandra Lochhaas, Jake S. Bennett et al. (+1 more)
The spatially-resolved kinematics of line emission from the circumgalactic medium (CGM) of a
galaxy can contain information about the CGM
turbulence, which may play an important role in
galaxy evolution. Due to the region's diffuse nature, there have been limited observations of low-
redshift CGM emission until recent efforts that use spatially-resolved emission line kinematics to probe CGM
turbulence. We use velocity structure functions (VSFs) as a measure for the properties of
turbulence using the high-resolution cosmological zoom-in FOGGIE simulations. We focus on the location of the "turnover" in the VSF slope, often used as a measurement of the
turbulence driving scale, and study how resolution, measurement area size, projection effects, and gas temperature influence the inferred CGM
turbulence driving scale. We find that projection significantly lowers the VSF normalization but we do not find significant differences in the slope between 3D VSFs and emission-weighted projected 2D VSFs. We find that the size of the area used to measure the VSF, which can be thought of as the size of the emission nebula for a given instrument sensitivity, correlates directly with the turnover location in the VSF. These dependencies should be considered when using VSFs to interpret CGM
turbulence from emission data, as projection, resolution and sensitivity constraints, and the temperature of the gas probed will all have a measurable effect on the VSF structure and the corresponding inferred turbulent properties.
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All authors Helena Bouchereau, Cassandra Lochhaas, Jake S. Bennett, Mandy C. Chen
Astrophysics of Galaxies
The VariableTNG project: Unveiling the physical drivers of galaxy quenching
Ignacio G. Alfaro, Antonio D. Montero-Dorta, Hong Guo et al. (+4 more)
Understanding the physical processes that regulate
galaxy quenching is a key challenge in
galaxy formation and
evolution. The VariableTNG (VTNG) project provides a laboratory to investigate these processes, as it systematically varies eight parameters of
galaxy formation while keeping the initial conditions fixed, allowing the effects of individual feedback prescriptions to be isolated. We use interpretable machine-learning techniques as a tool to identify the parameters that most strongly regulate the quenched
galaxy fraction. Our goal is to quantify the relative importance of the
galaxy formation and feedback parameters that regulate the quenched
galaxy fraction at z=0, determine how their influence changes across stellar mass and environment. We compute the quenched
galaxy fraction for 26 VTNG boxes as a function of stellar mass, black hole mass, and gas mass, considering both the total
galaxy population and separate samples of central and satellite
galaxies. We train Random Forest regressors to predict the variation of the quenched fraction relative to the TNG100-1 model and use SHAP values to quantify both the magnitude and direction of the influence of each parameter. Our analysis reveals that only a small subset of the VTNG parameters dominates the variance of the quenched fraction. The stellar feedback wind parameter is the primary driver at low stellar masses, while its importance gradually shifts toward AGN-related parameters at higher masses. The
supernova temperature also plays an important role at both extremes of the stellar-mass range. This transition persists when the
galaxy population is divided into central and satellite systems. Comparisons with observational measurements further suggest that variations in these feedback parameters may contribute to the discrepancies between the fiducial TNG100-1 model and the observed passive
galaxy population.
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All authors Ignacio G. Alfaro, Antonio D. Montero-Dorta, Hong Guo, Catalina Riveros-Jara, Kexin Liu, Yikai Liu, Luis C. Ho
Astrophysics of Galaxies · Cross-listed from astro-ph.SR
Sr and Ba yields of the First Generation(s) of stars: Constraints from metal-poor stars
Sarah Hughes, Anna Frebel, Xiaowei Ou et al. (+6 more)
We present our chemical abundance analysis of ten new extremely metal-poor
stars with $-4.05\leq\mbox{[Fe/H]}\leq-2.33$, based on high-resolution (R $\sim28,000$) Magellan/MIKE spectra. Eight of our
stars have low heavy-element abundances of $\mbox{[Sr/H]}<-4.5$ and $\mbox{[Ba/H]}<-4.0$, making them Small Accreted Stellar System (SASS)
stars. Four are hyper
neutron-capture-element poor with $\mbox{[Sr/H]}<-5.0$, including Gaia DR3 5729400267359655680, which sets a new record for the lowest detected Sr abundance of $\mbox{[Sr/H]} =-6.4$. We identify four distinct [Sr/Ba] groups within the wider SASS
star population which span a large range from $\mbox{[Sr/Ba]} =-2.0$ to +1.6, pointing to multiple types of progenitor events and different nucleosynthesis processes/sites. To explore the origins of this large [Sr/Ba] range, we adopt site-agnostic Sr yields of $\mbox{[Sr/H]}=-6$, $-5.75$, $-5.42$, and $-4.93$ for the four groups. Applying those yields suggests that the majority of SASS
stars formed from gas enriched by $\sim$1-10 progenitor events, consistent with expectations from their extremely metal-poor nature. We thus attribute the [Sr/H] abundance scatter to intrinsic variations in the Sr yield per nucleosynthesis site/event. Our proposed Sr yields for each [Sr/Ba] group and associated nucleosynthesis origin are a reasonable and representative approximation, good to within a factor of a few, and can constrain future theoretical heavy element nucleosynthesis calculations in early core-collapse
supernovae.
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All authors Sarah Hughes, Anna Frebel, Xiaowei Ou, Alexander Yelland, Felicia Xiao, Jorian Benke, Kali Kraus, Reidyn Wingate, Mohammad Mardini
Astrophysics of Galaxies
Diverse ionized gas conditions in a dynamically hot, interacting galaxy at $z = 9.31$ revealed by JWST/NIRSpec IFU
Ryota Ikeda, Takahiro Morishita, Massimo Stiavelli et al. (+1 more)
We present a spatially and spectrally resolved study of an interacting
galaxy, Gz9p3 at $z=9.31$, using the James Webb Space
Telescope NIRSpec/G395H IFU observation with high-spectral resolution ($R\approx 2700$) mode. Gz9p3 consists of two sub-regions (`core' and `tail'), which show stark contrast in their physical properties. The HII regions in the core are characterized by high electron density ($n_{e}\gtrsim2900$ cm$^{-3}$), low gas-phase
metallicity ($0.25$ dex below the mass-
metallicity relation), and yet relatively low specific
star formation rate (sSFR) among the system. On the other hand, the tail exhibits low electron density ($n_{e}<70$ cm$^{-3}$), relatively high gas-phase
metallicity that is consistent with the mass-
metallicity relation, and high sSFR. The integrated spectrum thus shows the properties inbetween these two regions. No evidence of ordered rotation in ionized gas is found, suggesting that Gz9p3 is a dynamically hot system. Finally, we find ionized gas outflows characterized by the secondary [OIII]5007 line component throughout most of the system. The outflow velocity is below the escape velocity, making Gz9p3 one of the first galactic systems experiencing a galactic fountain. Overall, our findings indicate that this system is in a phase in which the pristine gas is falling efficiently into the core, diluting the gas
metallicity, and enhancing
star formation and outflows after the
galaxy interaction.
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All authors Ryota Ikeda, Takahiro Morishita, Massimo Stiavelli, Antonello Calabrò
Astrophysics of Galaxies
Interacting stellar winds feeding Sgr A*: from the system of mass-losing stars to the binary IRS 16SW
Diego Calderón, Jorge Cuadra, Christopher M. P. Russell et al. (+3 more)
The discovery of cold structures around Sgr A* has challenged our understanding of the gas dynamics and thermodynamic state of the
plasma in its vicinity. This work aims to constrain the conditions for the formation of such structures, namely the cold disc-like structure and the recently discovered G-1-2-3 complex. We conduct hydrodynamic simulations of the observed Wolf-Rayet
stars feeding Sgr A*. Our simulations show that the
plasma chemical composition is crucial for determining the medium properties. We demonstrate that the formation of a cold disc is possible for chemical compositions that are consistent with observational constraints. However, it is not possible to reproduce all the properties of the observed disc which might suggest the interaction with another structure. Additionally, we present our first results on the hydrodynamic modelling of IRS 16SW as a colliding-wind binary. This is the first step to develop a realistic model on the formation of the G-1-2-3 complex.
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All authors Diego Calderón, Jorge Cuadra, Christopher M. P. Russell, Andreas Burkert, Stephan Rosswog, Mayura Balakrishnan
Astrophysics of Galaxies
A comprehensive cluster census of Orion. An application of the Significance Mode Analysis (SigMA) algorithm
Alena Rottensteiner, Sebastian Ratzenböck, João Alves et al. (+2 more)
Precise astrometric surveys and modern clustering
algorithms are working in step to transform our view of
star-forming regions. By revealing a much richer substructure than previously accessible, they pave the way for reconstructing
star formation histories by accurately resolving and age-dating individual sub-populations. The Orion
star-forming complex is the best-studied stellar nursery in the solar neighborhood and the nearest one currently forming massive
stars. Even so, a comprehensive characterization of its substructure, including a homogeneous age mapping and extinction analysis, is still incomplete. Here, we present the most complete census of stellar populations across the Orion complex from the newest version of the SigMA
algorithm and outline our additions and improvements to the
algorithm that have extended its usage to distant (>300 pc) regions. We separate the Orion complex into 47 co-spatial and co-moving stellar groups comprising 11,996 reliable members, with ages ranging from 1.5 to 25 Myr. To evaluate the statistical robustness of each group, we derive cluster persistence values and individual membership probabilities for each source from 10 independent clustering repetitions. Our group memberships agree well with the literature, but SigMA consistently finds a factor of ~2-3 more members. In particular, it resolves more very young populations, such as NGC 2024, RV Orionis, B30, NGC 1977, NGC 2068, and NGC 2071, than previous
algorithms. In addition to recovering 28 known clusters and three groups previously classified as substructures, we present 16 new co-eval substructure candidates of the Orion
star-forming complex. This work builds up a new high-resolution time-resolved picture of Orion. This spatio-temporal map allows us to relate its stellar content to the surrounding ISM and paves the way for a detailed analysis of its
star formation history in the future.
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All authors Alena Rottensteiner, Sebastian Ratzenböck, João Alves, Stefan Meingast, Sebastian Hutschenreuter
Astrophysics of Galaxies · Cross-listed from astro-ph.HE
Probing the $\gamma$-ray emission region and the connection to jet ejections in NRAO 150 with VLBI
L. C. Debbrecht, G. F. Paraschos, E. Ros et al. (+7 more)
Relativistic jets launched by active galactic
nuclei are fundamental for understanding the physics of accreting supermassive black holes and their immediate environments, yet the origin of these jets remains an open question. NRAO 150 is a blazar with a complex relativistic jet morphology that evolves on short timescales due to strong projection effects, enabling detailed kinematic analysis. In this study, we utilise data by the Very Long Baseline Array and the European VLBI Network from 2010 until 2019 at 43 GHz, to understand the formation and launching processes of the jet in NRAO 150. We study the $\gamma$-ray and
radio light-curves, together with total intensity and linear polarisation information to probe the connection between flaring events, $\gamma$-ray emission, and the ejection of new jet features. Furthermore, we investigate the
magnetic field configuration in the innermost jet region, as captured in polarised light, to gain insights about its configuration before, during, and after a $\gamma$-ray
flare. Our results indicate a close temporal link between the $\gamma$-ray flaring activity and the ejection of new VLBI jet components, suggesting that the high-energy emission is produced downstream of the VLBI core. The combined kinematic and polarimetric evidence further points to a toroidal
magnetic field in the inner jet, highlighting the key role of
magnetic fields in governing both jet dynamics and high-energy emission in NRAO 150.
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All authors L. C. Debbrecht, G. F. Paraschos, E. Ros, I. Agudo, T. P. Krichbaum, H. Müller, S. G. Jorstad, A. P. Marscher, M. A. Gurwell, J. A. Zensus
Astrophysics of Galaxies
A Critical Eddington Ratio for X-Shaped Radio Galaxies
David Garofalo
We derive a quantitative condition for the formation of X-shaped
radio galaxies by evaluating the competition between black hole
spin evolution and the radiative fading of relic
plasma within our previously proposed framework. The simultaneous visibility of two jet axes requires that the timescale for
spin evolution across zero, t_trans, be shorter than the fading timescale of relic
radio emission, t_fade. We estimate the transition timescale as t_trans about 5 million /lambda yr, where lambda is the Eddington ratio, and derive a visibility timescale t_fade about equal to 5-20 Myr based on the
evolution of the synchrotron break frequency for typical lobe
magnetic fields and
redshifts. This leads to a critical Eddington ratio lambda_crit in the range 0.3-1, above which systems can exhibit X-shaped morphologies. We show that this threshold naturally produces an environmental dependence, as radiatively efficient
accretion is more readily sustained in low-density environments, while feedback in rich clusters tends to drive systems toward radiatively inefficient states with a larger fraction of systems having lambda much less than lambda_crit, suppressing XRG formation. We further demonstrate that the observed low fraction of X-shaped
radio galaxies (about 1-5%) arises from the limited overlap window combined with
geometric and detectability effects. These results provide a quantitative and testable extension of our previous model, linking X-shaped morphology to
accretion rate and environmental conditions through a simple timescale criterion.
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Astrophysics of Galaxies
Identifying AGNs from X-ray detections$-$II: Metallicity calibrations for the $\rm N_2O_2$ and $\rm N_2S_2$ diagnostics
Mark Armah, O. L. Dors, Rogério Riffel et al. (+4 more)
Emission-line ratios from ions with nearly identical ionization potentials offer a robust solution to the degeneracies inherent to traditional active galactic
nuclei (AGNs)
metallicity diagnostics. We introduce new semi-empirical
metallicity calibrations for the $\rm N_2O_2$ and $\rm N_2S_2$ diagnostics, explicitly designed to isolate the chemical abundance from the incident radiation field. By coupling an extensive grid of CLOUDY photoionization simulations directly to the intrinsic 2$-$10 keV X-ray luminosity ($L_{\rm X}$) and benchmarking against Seyfert~2
nuclei from the Burst Alert
Telescope AGN Spectroscopic Survey (BASS), we establish robust relations valid across the
metallicity regime of $8.0 \lesssim 12+\log({\rm O/H}) \lesssim 9.1$ ($0.2 \lesssim Z/Z_{\odot} \lesssim 2.6$). The $\rm N_2O_2$ and $\rm N_2S_2$ indices trace co-spatial emitting volumes within the narrow-line regions (NLRs), enabling this framework to resolve the significant $L_{\rm X}$-driven systematic biases we previously identified in the standard $\rm N_2$ and $\rm N_2O_3$ indices. While the $\rm N_2O_2$ ratio proves to be virtually independent of nebular structural variations, the $\rm N_2S_2$ index exhibits a subtle, yet discernible, electron density ($N_{\rm e}$) susceptibility due to the low critical density ($N_{\rm c}$) of the [S II]$\lambda\lambda6716,6731$ doublet. Nevertheless, both diagnostics yield highly precise
metallicity constraints with tight root-mean-square residual dispersions of $\sim 0.081$ dex for $\rm N_2O_2$ and $\sim 0.121$ dex for $\rm N_2S_2$. We propose the $\rm N_2O_2$ and $\rm N_2S_2$ calibrations as highly optimized, unbiased
metallicity tracers for AGNs.
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All authors Mark Armah, O. L. Dors, Rogério Riffel, M. V. Cardaci, G. F. Hägele, Rogemar A. Riffel, J. M. Vílchez
Astrophysics of Galaxies · Cross-listed from astro-ph.SR
Eta Carinae's historical light curve: evidence for cyclic Roche lobe overflow from the primary star
Augusto Damineli, Leonardo A. Almeida, Francisco J. Jablonski et al. (+5 more)
The large amount of ground-based photometric measurements of $\eta$ Carinae obtained since 1940 have remained problematic for quantitative modeling due to the blending of flux from the stellar core and the surrounding circumstellar nebula. In the era of the Hubble Space
Telescope, spatially resolved imaging & spectrophotometry have enabled disentanglement of these components, allowing recovery of the stellar core $V$-band brightness from ground-based observations. We isolate the $V$-band fluxes of the stellar core and nebula using 1999–2020 HST (ACS and STIS) observations, and use these to calibrate coeval ground-based photometry. The main finding is an orbital light curve with an amplitude $\Delta m \approx \pm 0.2\,$mag, many times higher than that modeled by ellipsoidal deformation of the primary. The observations suggest that Roche lobe overflow starts at $- 75$ days before periastron in coincidence with the start of rising in the orbital light curve, and remains for 150 days. An expanding (and afterwards dissipating) gas cloud reflecting the light from the primary would explain the observed large amplitude of the orbital light curve. A sharp periodic photometric peak occurs at $\sim -18$ days from the periastron. It is followed by a broad minimum around the superior conjunction of the secondary (T$_0+5.2$ days), which we interpret as a partial eclipse of the ejected material, in coincidence with the shallow minimum in X-rays, which also has been attributed to an eclipse.
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All authors Augusto Damineli, Leonardo A. Almeida, Francisco J. Jablonski, Eduardo Fernández-Lajús, Felipe Navarete, Eder Martioli, Gerd Weigelt, Rodrigo Capobiango
Astrophysics of Galaxies
JWST Whirlpool Galaxy Treasury: Mid-Infrared Emission in M51 and its Relation to Gas Column and Star Formation
Mansi Padave, Karin M. Sandstrom, Daniel A. Dale et al. (+25 more)
Using JWST/MIRI imaging of M51 in eight broadband filters, we investigate correlations of mid-infrared emission from polycyclic aromatic hydrocarbons (PAHs) and dust continuum with molecular, atomic, and ionized gas traced by CO(1-0), HI, and Pa-alpha, respectively. In molecular gas-dominated regions, PAH-dominated filters (F560W, F770W, F1130W, F1280W) exhibit near-linear correlations with CO(1-0) at 40 pc scale, indicating that PAHs are well-mixed with gas and experience relatively constant radiation field intensities. The F1500W, F1800W, and F2100W dust continuum-dominated filters show shallower slopes with CO(1-0), reflecting contributions from
star-forming regions with high radiation field intensities. This is reinforced by the near-linear scaling between F2100W and Pa-alpha. PAH-dominated bands do not show this linear trend with Pa-alpha, likely due to their destruction in ionized regions. F1000W behaves similarly to PAH bands in its correlations with CO(1-0) and Pa-alpha. Modeling mid-infrared emission with an empirical decomposition into gas- and
star-formation-associated components shows that PAH-dominated filters receive comparable contributions from both, while the relative contribution associated with the Pa-alpha template increases toward longer wavelengths, reaching $\sim$75% in F2100W. These results demonstrate that mid-infrared simultaneously traces the gas column and
star formation, but with a systematic wavelength-dependent shift in what drives the correlations: PAHs being more gas-tracing and dust-continuum reflecting
star formation. Lastly, considering both HI and H$_2$ at 440 pc resolution, we find a tight, linear relation between $\Sigma_{HI+H_2}$ and PAH-dominated filters. Although most of our coverage is in H$_2$-dominated regions, we note similar observations with HI, suggesting that PAHs are also well-mixed with atomic gas.
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All authors Mansi Padave, Karin M. Sandstrom, Daniel A. Dale, Adam K. Leroy, Eric W. Koch, Tony D. Weinbeck, Angela Adamo, Jessica Sutter, Lindsey Hands, Torsten Böker, Martha L. Boyer, Ryan Chown, Bruce T. Draine, Ilse de Looze, Brandt A. L. Gaches, Simon C. O. Glover, Dario Colombo, Robert C. Kennicutt Jr., Hannah Koziol, Ralf S. Klessen, Sean T. Linden, Desika Narayanan, Alex Pedrini, Julia Roman-Duval, Eva Schinnerer, J.D.T. Smith, Sophia K. Stuber, Fabian Walter
Astrophysics of Galaxies · Cross-listed from astro-ph.HE
A Cross-Band (X-ray $\times$ Optical) Periodicity Search for Supermassive Black Hole Binaries: A Null Result and the First Completeness-Corrected Constraint
Karan Akbari
We present the first sample-level search for supermassive black hole binaries (SMBHBs) requiring coherent quasi-periodicity at a common period in the X-ray and optical bands, over 1194 Swift-BAT hard X-ray AGN (Stage 1) and 175 4XMM-DR14 AGN (Stage 2). No source is a co-periodic candidate. Each light curve is modelled as a damped random walk (DRW) and searched with a Lomb-Scargle periodogram and a look-elsewhere-corrected Monte-Carlo significance. Because DRW red noise is largely independent between corona and disc, we require both bands individually significant with periods coincident within 5%, and gate the survivors with the model-independent null-signal-template test of Robnik et al. (2024). Over $P=100$-$900$ d the completeness-corrected 95% upper limit on the co-periodic fraction is amplitude-dependent: $\lesssim 3\%$ for hard-X-ray fractional modulation $\gtrsim 0.3$, $\approx 15\%$ (precision-limited) at 0.2, and uninformative below $\sim 0.15$ (the $\epsilon=1$ floor is 0.25%). The sensitivity is set by the hard X-ray monitoring, not the optical photometry or the statistics, the opposite of the usual assumption. Daily MAXI and RXTE/ASM monitoring of the brightest AGN raises the X-ray completeness 5-8-fold, and the search remains null. Integrated over the BAT black-hole mass function, the expected all-amplitude co-periodic fraction is $\sim 3\times10^{-2}\, f_{\rm bin}\, \delta_{\rm mod}$ (modulo a factor $g<1$), with $f_{\rm bin}$ the sub-pc binary fraction, $\delta_{\rm mod}$ the modulating duty cycle, and $g$ the fraction reaching recoverable hard-X-ray amplitude, so a null is expected. We deliver a validated cross-band framework and the first completeness-corrected constraint on the co-periodic fraction, ready for the denser X-ray monitoring of Einstein Probe and eROSITA.
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Astrophysics of Galaxies · Cross-listed from astro-ph.HE
Inclination Diffusion in Relativistic Loss Cones
Wenkang Xin
Relativistic capture and tidal disruption around a spinning black hole depend on both the magnitude and direction of the
star's angular momentum, yet loss-cone models often assume fixed orbital inclinations by ignoring the associated
diffusion. We show that this is not justified: for isotropic two-body relaxation near a small loss threshold, angular-momentum magnitude $L$ and inclination $x = L_{z}/L$ diffuse on comparable timescales, $t_{E} \gg t_{L} \sim t_{x}$. For Kerr capture, retaining inclination
diffusion significantly amplifies the prograde–retrograde contrast while leaving the total inclination-integrated flux nearly unchanged. An almost correct integrated flux can hide a badly wrong angular distribution. The three-dimensional
diffusion problem nevertheless retains enough angular structure to permit analytic treatment. By representing pericenter removal as a continuous sink, we obtain a closed-form loss flux solution for a nearly linear Kerr tidal-disruption boundary, finding close agreement with phase-resolved calculations. Inclination-dependent loss therefore requires inclination-resolved
diffusion even when integrated rates appear robust.
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Astrophysics of Galaxies
A posteriori correction of Gaia CRF proper motions using conditional probability and zero-parallax prior
Valeri V. Makarov
Precision of proper motions and positions given in the Gaia Celestial Reference Frame (CRF) catalog can be statistically improved introducing conditional probability based on the prior knowledge of zero parallax for these extremely distant sources. The method developed in this study produces statistically conditioned proper-motion estimates under the assumed per-source Gaussian covariance model. It is demonstrated that thus corrected proper motion vectors of 1.2 million CRF objects in Gaia DR3 show a tighter distribution around zero and a general reduction in the rate of outliers by approximately 15%. A general vector spherical harmonic fit to degree 4 is produced with the corrected data for a filtered subset of CRF
quasars with
redshifts between 1 and 1.5. This application, predicated on the unknown
stochastic component of the global parallax field, shows a 3-sigma change in the estimated magnitude of the Galactocentric acceleration of the solar system barycenter, quantifying the sensitivity of this fundamental determination to the proposed conditioning of proper motions.
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Astrophysics of Galaxies
High Velocity Neutral Gas in the Fermi Bubbles: New Kinematic Limits and Spatial Structure
Felix J. Lockman, Enrico M. Di Teodoro, Savannah Cary et al. (+1 more)
We have detected hundreds of neutral clouds entrained in the Milky Way's nuclear wind using HI data from new surveys made with the Green Bank
Telescope that cover about 500 sq-degrees around the Galactic center (GC). Galactic winds are common throughout the Universe, and these data at 9.1' angular resolution (22 pc at the GC) provide the most detailed analysis of the vertical profile of a neutral nuclear wind in any
galaxy. A set of 228 of these Fermi Bubble clouds with the largest values of |VLSR| has been analyzed to examine the distribution and kinematics of the outflowing gas. The clouds span -335 km/s $\leq$ VLSR $\leq$ +438 km/s, the largest positive LSR velocities ever reported for neutral HI associated with the Milky Way disk. The highest velocities are found furthest from the GC, suggesting that clouds are accelerated from a low velocity near the
nucleus to at least 500 km/s at a radial distance of $\lesssim 4$ kpc. Clouds appear disrupted as they are accelerated: their line brightness and NHI decreases steadily with distance from the GC, and the population becomes more uniform. There is an abrupt cutoff in the neutral clouds at a vertical distance of $\approx2$ kpc from the Galactic plane. Kinematic models of an outflowing cloud population that fills the FB volume are used to identify structure in the gas. The kinematics of the highest velocity, highest latitude clouds imply a past azimuthal asymmetry in the outflow.
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All authors Felix J. Lockman, Enrico M. Di Teodoro, Savannah Cary, Andrew J. Fox
Astrophysics of Galaxies
Two domains of extended Lyman-alpha emission around galaxies: from local radiation to environmental regulation
Daria Kozlova, Lutz Wisotzki, John Pharo et al. (+7 more)
We examine the relation between extended Ly$\alpha$
halos around high-
redshift galaxies and the main factors responsible for driving the emission in such
halos, in particular at distances around and beyond one virial radius $r_\mathrm{vir}$. To reach the required surface brightness sensitivity we take advantage of the MUSE eXtremely Deep Field (MXDF) survey, allowing us to probe levels as faint as $\sim 10^{-20}$ erg cm$^{-2}$ s$^{-1}$ arcsec$^{-2}$ in individual Ly$\alpha$
halos. Our sample consists of the 21 apparently core- and
halo-brightest (yet intrinsically low luminosity $\log_{10}$L$_{\mathrm{Ly}\alpha} < 42.3$ erg s$^{-1}$) Ly$\alpha$ emitters (LAEs) in the MXDF at $3<z<4$, with typical virial radii around 20 kpc. We measure their radial surface brightness profiles out to 50 kpc (more than $2r_{\mathrm{vir}}$) and investigate the correlations between surface brightness and internal (
star formation rates of the host
galaxies, SFR) or external influences (environmental density, $\delta+1$). We find a clear break in these correlations at radii around or just below $1r_{\mathrm{vir}}$. Below this break the emission correlates tightly with SFR (as expected) and not at all with $\delta+1$. Beyond $\sim 1r_\mathrm{vir}$(20 kpc) we observe the opposite trend with no dependence on SFR, but an emerging correlation with $\delta+1$. We compare our measurements with the expected integrated surface brightness from ultrafaint, individually undetected LAEs and find that the latter is insufficient to drive the observed correlation. We conclude that Ly$\alpha$ emission from the outer
halos is regulated by the surrounding environment, but originates mostly from diffuse gas rather than discrete sources.
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All authors Daria Kozlova, Lutz Wisotzki, John Pharo, Tanya Urrutia, Ramona Augustin, Yucheng Guo, Haruka Kusakabe, Joop Schaye, Daniil Smirnov, Ismael Pessa
Astrophysics of Galaxies · Cross-listed from astro-ph.SR
CO rotational line emission in very red carbon stars in the Magellanic Clouds
M.A.T. Groenewegen, A. Nanni, M.L. Boyer et al. (+11 more)
Stars of low and intermediate initial mass lose most of their stellar mass at the end of their lives during the asymptotic giant branch (AGB) phase. Determining their gas and dust mass-loss rates (MLRs) is crucial for quantifying the contribution of evolved
stars to the life cycle of dust and gas in the Universe. The Atacama Large Millimeter/submillimeter Array was used to observe 38 carbon
stars (C
stars) in the large Magellanic cloud (LMC) and three C
stars in the small Magellanic cloud (SMC) in the CO J= 2-1 line. Line profiles were fitted to derive stellar velocities and wind-expansion velocities (Vexp). CO emission is detected in two C
stars in the SMC and 33 C
stars in the LMC. This is the first detection of carbon monoxide around an AGB
star in the SMC. One object in the LMC shows emission in $^{13}$CO. The wind-expansion velocity ranges from \sim7.5 to \sim30 km/s. Archival data were used to determine the pulsation periods as well as construct and model the spectral energy distributions using two dust radiative transfer codes. Mass-loss rates were independently derived from these two codes as well as from the intensity of the CO line, using a simple formula. On average, the dust-based MLRs higher than the MLRs based on the CO line by a factor of 1.6. Additional CO data in other transitions, combined with proper modelling, is required to further investigate this possible discrepancy. Mass-loss rates, pulsation periods, and expansion velocities were compared to a sample of Galactic C
stars. There is a strong bias, as the Magellanic Cloud targets sample the highest MLRs and luminosities, yet they represent only a minority of
stars in a Galactic sample. Comparing this sample with a similarly extreme set of Galactic
stars with periods longer than 500 days, we identify no correlation between
metallicity and either the MLR or Vexp.
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All authors M.A.T. Groenewegen, A. Nanni, M.L. Boyer, L. Decin, S.R. Goldman, K. Justtanont, F. Kerschbaum, I. McDonald, H. Olofsson, R. Sahai, G. C. Sloan, J. Th. van Loon, W.H.T. Vlemmings, A.A. Zijlstra
Astrophysics of Galaxies
RIOJA. Environmental Effects on Stellar Populations and Ionized Gas in a Protocluster at $z=7.88$
Wataru Osone, Takuya Hashimoto, Javier Álvarez-Márquez et al. (+23 more)
Protoclusters in the epoch of reionization provide key laboratories for investigating how environment shapes early
galaxy formation and
evolution, and may also have contributed to
cosmic reionization. We analyze 23 member
galaxies of A2744-z7p9OD, a protocluster at $z=7.88$, using JWST/NIRCam and NIRSpec to investigate their stellar population properties, rest-frame UV sizes, and ionized-gas properties. We also quantify the internal structure of A2744-z7p9OD using the projected distance to the most massive
galaxy ($D_{\rm YD4}$), and to the nearest neighbor ($D_{\rm nei}$), as global and local environmental indicators, respectively. Stellar mass, SFR on a 100 Myr timescale, dust attenuation, and
galaxy size show significant correlations ($p<0.05$) with $D_{\rm YD4}$, but not with $D_{\rm nei}$, suggesting that these properties are primarily linked to the global protocluster structure. The member
galaxies also show a large
galaxy-to-
galaxy variation in R23 ($=\log{(([\mathrm{O}\text{\textsc{iii}}]\lambda\lambda4960,5008\rm{\AA}+[\mathrm{O}\text{\textsc{ii}}]\lambda\lambda3727,3730\rm{\AA})/\rm{H}\beta)}$), implying inhomogeneous chemical enrichment in the protocluster environment. O32 ($=\log{([\mathrm{O}\text{\textsc{iii}}]\lambda5008\rm{\AA}/[\mathrm{O}\text{\textsc{ii}}]\lambda\lambda3727,3730\rm{\AA})}$) correlates with $D_{\rm YD4}$, indicating that the core region is characterized by low-ionization gas. Together with the non-detection of Ly$\alpha$ emission, the possible neutral-gas reservoir traced by ALMA [Cii]~$158\mu$m emission, and evidence for high-column-density neutral hydrogen in the core, this suggests a neutral-gas-rich protocluster core where the current escape of ionizing
photons may be suppressed, even in a overdense environment during the EoR.
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All authors Wataru Osone, Takuya Hashimoto, Javier Álvarez-Márquez, Luis Colina, Akio K. Inoue, Ken Mawatari, Yuma Sugahara, Carmen Blanco-Prieto, Takeshi Hashigaya, Takahiro Morishita, Massimo Stiavelli, Santiago Arribas, Tom J. L. C. Bakx, Daniel Ceverino, Alejandro Crespo Gómez, Yoshinobu Fudamoto, Masato Hagimoto, Asahi Hamada, Rui Marques-Chaves, Yurina Nakazato, Hideki Umehata, Hidenobu Yajima, Hiroshi Matsuo, Naoki Yoshida, Yi W. Ren, Yoichi Tamura
Astrophysics of Galaxies
Coronal gas excitation as a tracer of supermassive black hole mass: on the mid-IR coronal [Ne v] lines
J. S. Elford, A. Prieto and A. Rodríguez-Ardila
Coronal lines (CL) may be a reliable proxy of supermassive black hole (SMBH) masses in active galactic
nuclei (AGN) because the production of these high ionisation potential (IP) lines is sensitive to the shape of the ionising continuum which, for a thin
accretion disc, relies on the black hole mass. In this work we study the connection between the [Ne\,v] coronal lines and the SMBH mass. We analyse the Spitzer spectra of a sample of 27 AGN spanning three orders of magnitude in SMBH mass. Fluxes and the electron density in the coronal gas medium were measured after fitting Gaussians to both the $\rm [Ne\,v]14\mu m$ and $\rm [Ne\,v]24\mu m$ lines where detected at high signal to noise. Line fluxes were normalised to the Br$\gamma_{\rm broad}$ emission from the broad line region. We found strong correlations between the $\rm [Ne\,v]14\mu m/Br\gamma_{\rm broad}$ and $\rm [Ne\,v]24\mu m/Br\gamma_{\rm broad}$ line ratios and the SMBH mass. For this sample of 27 AGN we find scatters of 0.54 and 0.53 dex, respectively. These correlations support the theory that the coronal gas excitation is sensitive to a range of SMBH masses because of the dependence on the shape of the ionising continuum. The electron densities of the coronal medium are of the order 1000$\rm cm^{-3}$ supporting their nuclear origin. A comparison with density values derived from JWST for a subsample of objects confirm this conclusion. These results further demonstrate the ability to use CL as a SMBH mass proxy, allowing for accurate SMBH mass measurements in AGN.
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Astrophysics of Galaxies
A Radio-Bright Local Little Red Dot Analog
Luis F. Rodriguez, I. FElix Mirabel, Rosa A. Gonzalez-Lopezlira et al. (+1 more)
The James Webb Space
Telescope revealed the existence in the early Universe ($z >$ 4) of large populations of little red dots (LRDs), compact red luminous sources that host rapidly growing supermassive black holes (SMBHs) surrounded by coeval nuclear starbursts. LRDs have defining properties, one of which is the absence of
radio detections. LRDs could be
radio-undetected because of their large distances. A way to investigate the
radio properties of LRDs is to search for
radio emission in their local analogs, the Local Little Red Dot (LLRD)
galaxies at $z <$ 1 with analogous properties to LRDs. We report the
radio continuum detection of the LLRD analog J204837.26${-}$002437.2 ($z$ = 0.4332, hereinafter J2048). This adds to the previous
radio detection of two other LLRDs. However, with a flux density of 3.0$\pm$0.2 mJy at 3.0 GHz, J2048 is two orders of magnitude more
radio luminous than the previous detections. The spectral index of $\alpha$ = -0.39$\pm$0.04 is consistent with moderately optically-thick synchrotron emission. The
radio luminosity of J2048 is $1.2 \times 10^{41}~ \mathrm{erg ~s^{-1}}$, in the lower end of the range defined by
radio-loud giant elliptical
galaxies and
quasars of $L_R$ = $10^{41-46} ~\mathrm{erg ~s^{-1}}$. The expected
radio luminosity of the SMBH associated with J2048 is estimated to be about an order of magnitude larger, suggesting that its
radio luminosity could potentially be strongly dimmed. A cosmological ($z >$ 4) LRD with
radio luminosity similar to that of J2048 would be detectable using the VLA with moderately long integrations.
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All authors Luis F. Rodriguez, I. FElix Mirabel, Rosa A. Gonzalez-Lopezlira, Laurent Loinard
Astrophysics of Galaxies
Star Formation in the H II Region Sh 2-205: 3D Morphology and Kinematics from Young Stars and Molecular Gas
Yiwei Dong, Chaojie Hao, Ye Xu et al. (+5 more)
Using Gaia astrometry of young
stars combined with CO observations, we present the first systematic three-dimensional (3D) analysis of the structure, kinematics, and evolutionary history of the
star-forming regions in the environs of the H II region Sh 2-205 (S205). S205 exhibits a complex morphology and coherent expansion on both global and subregional scales. We identify several O9-B1
stars and a 0.56 Myr old
pulsar that are likely associated with the region. A momentum estimate suggests that feedback from these objects may account for the observed overall expansion. Trace-back analysis of the expansion, combined with color-magnitude diagram fitting for young
star clusters, indicates at least two episodes of
star formation. These results reveal a complex
star-formation history of S205 and provide new insights into its 3D
evolution.
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All authors Yiwei Dong, Chaojie Hao, Ye Xu, Yingjie Li, Zehao Lin, Dejian Liu, Yan Sun, Longhui Yang
Astrophysics of Galaxies
Catalytic formation of H_2 on carbonaceous dust grains - implications for interstellar observations
Aryav Das, Julia Gao, Daniel Vrinceanu et al. (+1 more)
We use kinetic Monte Carlo (KMC) simulations to study molecular hydrogen formation on carbonaceous dust grain surfaces, validated against recent laboratory measurements of H$_2$ formation on coronene films at temperatures from 10 to 250 K. The model uses a three-dimensional amorphous carbon
lattice with heterogeneous physisorption ($45 \pm 5$ meV) and chemisorption ($1.75 \pm 0.25$ eV) sites, and tracks both Langmuir–Hinshelwood (LH) and Eley–Rideal (ER) formation channels within a
stochastic Gillespie event-driven framework. The model reproduces the measured efficiency curve within the experimental uncertainties, including the isothermal (constant surface temperature) measurements at 100 - 250 K. The simulations correctly describe the phase boundary between the LH and ER driven processes as functions of grain temperature and the observed crossover. Under interstellar medium conditions, 10 - 250 K and n = 10 - 10$^4$ cm$^3$, the model predicts three distinct regimes for the formation efficiency $\epsilon$, the fraction of impinging H atoms released as H$_2$. At 10 K
diffusion is slow and $\epsilon \approx 0.06$. Between 20 K and 80 K, LH dominates and $\epsilon \approx 0.28$. Above 150 K, an ER plateau at $\epsilon = 0.19$ is sustained by chemisorption-trapped H atoms. The LH-to-ER crossover occurs between 100 and 120 K. At 100 K we observe a 16% density-dependent
stochastic enhancement, which rate-equation models cannot capture. At T$_{dust}$ = 60 K, n = 10$^3$ cm$^3$ we find the ratio of H$_2$ formation to free-fall time $t_{{\rm H}_2}/t_{\rm ff} \approx 0.93$, so dust-catalysed H$_2$ chemistry can keep pace with gravitational collapse in high-
redshift star-forming environments.
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All authors Aryav Das, Julia Gao, Daniel Vrinceanu, H. R. Sadeghpour
Astrophysics of Galaxies
The H$\alpha$ specific angular momentum of dwarf galaxies
Simon Deeley, Sarah Sweet, Dilyar Barat et al. (+3 more)
The relationship between a
galaxy's specific angular momentum $j$ and its mass $M$, parameterised by $j \propto M^\alpha$ and known as the Fall relation, has emerged as a fundamental scaling relation reflecting key physical and morphological properties of
galaxies. This relation has been well studied for
galaxies with masses above $10^{9}$ $M_{\odot}$. However, whether or not it holds for the low-mass dwarf
galaxies, especially given their varied morphologies, remains uncertain. Here we use H$\alpha$ observations of 49
star-forming dwarf
galaxies from the SH$\alpha$DE survey, as well as 20 high-mass `control'
galaxies, to investigate the stellar $j_{*}$-$M_{*}$ relation down to masses below $10^{6}$ M$_{\odot}$. We find that the
star-forming dwarf
galaxies follow the same $j_{*}$-$M_{*}$ relation as high-mass disk-like
galaxies, with $\alpha = 0.53 \pm{0.4}$, demonstrating that the relation holds across 5 orders of magnitude in mass. We then select a matching sample from the IllustrisTNG cosmological simulation and create mock observations resembling the SH$\alpha$DE survey. We find that the simulated dwarf
galaxy population follows the extrapolated $j_{*}$-$M_{*}$ relation with a flattening and significant scatter towards lower $j_{*}$ values. Following the
evolution of these
galaxies, we find that dwarf
galaxies experience a gradual loss in $j_{*}$ with time, while high-mass
galaxies experience a sudden jump in $j_{*}$ before settling into a stable state. This dynamical
evolution leads to a
redshift dependence in $\alpha$, with $\alpha = 0.45$ at $z = 2$ and 0.55 at $z = 0$. Despite the apparent simplicity in the present-day $j_{*}$-$M_{*}$ relation over a wide mass range, the
evolution of $j$ leading to this relation is complex and dynamic.
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All authors Simon Deeley, Sarah Sweet, Dilyar Barat, Matthew Colless, Luca Cortese, Francesco D'Eugenio
Astrophysics of Galaxies
Gaia DR3 Limits on Stellar Engine Technosignatures in Nearby Stars
Bo-Lun Huang, Zhen-Zhao Tao, Tong-Jie Zhang et al. (+1 more)
An operating stellar engine that transfers momentum to its host
star could produce an approximately persistent transverse acceleration during the Gaia Data Release 3 (DR3) observing epoch. We search for such accelerations among 406,984 quality-selected Gaia DR3
stars with nominal distances below 200 pc (about 650 light-years), using 8,890 published Acceleration7 solutions. Because long-period binaries and astrometric systematics can produce similar sky-plane
curvature, we model these conventional explanations together with a broad component that can absorb any remaining persistent acceleration or model mismatch. At $a_0 = 2.60 \times 10^{-4}$ m s$^{-2}$, where essentially the entire parent sample is searchable, mapping the residual weights evaluated at the one-sided 95% profile-limit point gives a parent-population fraction limit of $1.21 \times 10^{-5}$. Multiplying this fraction by the parent-sample size gives a summed upper-limit weight of about five
star-equivalents above the threshold. Toward the lowest acceleration thresholds, the searchable fraction declines rapidly, so the corresponding bounds primarily describe the reach of the search. No individual source is interpreted as a technological signal.
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All authors Bo-Lun Huang, Zhen-Zhao Tao, Tong-Jie Zhang, Zhi-E Liu