Astrophysics of Galaxies
Impact of LSST systematics on stellar-stream density fluctuations for dark matter
Matthieu Pélissier, Peter S. Ferguson, Alex Drlica-Wagner et al. (+6 more)
The Vera C. Rubin Observatory's Legacy Survey of Space and Time (LSST) is expected to significantly advance the study of Milky Way stellar streams. In particular, the deep, precise photometry from LSST should greatly increase the statistical sensitivity to density fluctuations in stellar streams, which can be used to probe the small-scale distribution of dark matter. However, current forecasts generally neglect the impact of observational systematics that will be imprinted on stream density measurements. In this study, we develop a realistic forward-modeling framework to inject stellar streams into LSST-like observations including photometric uncertainties, survey depth variations, background contamination, and imperfect
star-
galaxy classification. We develop a likelihood-ratio analysis to assess the detectability of gaps in stellar streams in the presence of these observational systematics. In the presence of realistic survey systematics, we find that after four years of operations, LSST will be sensitive to density reductions of $\sim50\%$ for gaps with widths of $5$ deg in streams with surface brightness of $\sim33$ mag arcsec$^{-2}$. Relative to the ideal case, this corresponds to a degradation in gap depth sensitivity by a factor of $\sim5$ due to the combined impact of background contamination and observational systematics. Assuming a simplified analytical mapping between gap depth and dark matter subhalo properties, these estimates correspond to a minimum detectable subhalo mass of $\sim1\times10^7$ M$_\odot$. Observational effects shift this accessible mass scale upward by a factor of $\sim16$, with background contamination contributing a factor of $\sim5$ and survey systematics a further factor of $\sim3$, dominated by
star-
galaxy classification.
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All authors Matthieu Pélissier, Peter S. Ferguson, Alex Drlica-Wagner, Marine Kuna, David Maurin, Christian Aganze, Johann Cohen-Tanugi, Yao-Yuan Mao, The LSST Dark Energy Science Collaboration
Astrophysics of Galaxies
Studying Outflows with Synthetic Absorption Line Spectra from High Resolution Simulations
Jake Magee, Evan Schneider, Kate H. R. Rubin et al. (+2 more)
Down-the-barrel absorption line spectra are a powerful probe of the properties of multiphase galactic outflows. In this work, we demonstrate a method to generate realistic synthetic spectra using high resolution ($\Delta x=5-20 \ \mathrm{pc}$), 20-kiloparsec-scale outflow simulations from the next generation of the CGOLS project. Aiming to mimic modern observational surveys of nearby
star-forming
galaxies, we generate a suite of UV absorption lines, from which we measure common observables such as equivalent widths and velocity statistics, and compare them to observed values. The velocity statistics from the simulated data agree well with high-resolution, far-UV HST treasury data, but the equivalent widths (EWs) display more variability. Our fiducial EWs are systematically lower than the empirical predictions by $\sim50-97\%$, particularly in the lines with higher ionization potentials, though these values increase with inclination angle,
star formation rate, and time. We find a strong correlation between the measured outflow velocity and ionization potential, reminiscent of the known correlation between velocity and temperature from the simulations. We also study the effect of simulation resolution on our statistics, finding the EWs to be much more sensitive to the simulation resolution than the velocities. Overall, we find that we can generate realistic synthetic spectra from high-resolution hydrodynamic simulations that are qualitatively similar to observations. In future work, we will further improve the physical realism of our synthetic spectra by implementing a more accurate ionizing background spectrum, with the ultimate goal of improving constraints on derived outflow properties from observations.
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All authors Jake Magee, Evan Schneider, Kate H. R. Rubin, S. Alwin Mao, Cameron Hummels
Astrophysics of Galaxies · Cross-listed from astro-ph.HE
XRISM observations of the Perseus cluster along two arms: Chaotic ICM motions probed by resonant scattering
Annie Heinrich, Irina Zhuravleva, Congyao Zhang et al. (+13 more)
XRISM has mapped gas velocities across the core of the Perseus cluster, separating the kinematic effects of mergers and AGN feedback. The physical properties of these motions remain unclear: are they a superposition of bulk flows, predominantly random/turbulent motions, or a mixture of both? Without resolving this question, constraints on the nonthermal pressure fraction and heating rate remain uncertain, as both assume predominantly random motions. Unlike emission line broadening, resonant scattering is most sensitive to small-scale, random motions rather than coherent bulk flows. Taking advantage of the extensive XRISM coverage of the Perseus cluster, we detect the full effects of resonant scattering on the He{\alpha} w line for the first time. This includes flux suppression in the cluster center, enhancement in the outer regions, and non-Gaussianity in the emission line. We employ radiative transfer simulations to constrain the amplitude of small-scale ICM velocities in the inner 60 kpc of Perseus, finding them to be consistent with the line broadening measurements within the uncertainties. This indicates the observed velocity dispersion is primarily due to small-scale random motions in the central Perseus regions rather than coherent bulk flows. We further explore potential anisotropy of these motions, showing that they are consistent with isotropic or radial motions rather than tangential ones. Longer XRISM observations are required to improve these anisotropy constraints. Finally, we explore azimuthal variations between the two complete radial arms observed by XRISM.
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All authors Annie Heinrich, Irina Zhuravleva, Congyao Zhang, Anna Ogorzalek, Ayşegül Tümer, François Mernier, Phillip C. Stancil, Elena Bellomi, Lior Shefler, John ZuHone, Yutaka Fujita, Julie Hlavacek-Larrondo, Yuto Ichinohe, Kyoko Matsushita, Nhut Truong, Shutaro Ueda
Astrophysics of Galaxies
The THRILS Factor: Investigating the properties of Little Red Dots (LRDs) at 3<z<6 with JWST/NIRSpec
Ananya Ganapathy, Rebecca L. Larson, Erini Lambrides et al. (+20 more)
JWST has uncovered a class of objects called LRDs, whose nature is still widely debated. In this work, we present a comprehensive spectroscopic analysis of nine LRDs in the Extended Groth Strip (EGS) field studied as part of THRILS and C3PO, both JWST Cycle 3 programs. These targets, photometrically selected based on their compact red appearance, are observed with deep spectroscopic exposures ($\geq8$ hours), enabling robust detections of broad Balmer lines, He I emission, and other spectral features characteristic of AGN activity. Using the [SII] $\lambda\lambda6716,6731$ doublet, we find electron densities ($n_e$) between $2.33 < \log (n_e) < 2.97 \ \mathrm{cm^{-3}}$, comparable to those in narrow line regions (NLR) of local AGN and high-$z$
galaxies. The spectroscopic depth further enables detailed characterization of broad Balmer line profiles. We fit both Gaussian and convolved exponential models to each source and find that five LRDs are statistically better described by the latter model. We measure optical depths $\tau_{\rm sc} = 0.56-0.91$, scattering fractions $f_{\rm SC} = 0.40-0.82$ which correspond to column densities log(N$_e$) $\sim$ 23.93-24.14 cm$^{-2}$, and covering fractions $c_f = 0.43-0.59$. These results indicate a clumpier broad line region (BLR) geometry that deviates from conventional LRD models, which predict covering fractions close to unity. Furthermore, these Compton-thick gas columns may explain the X-ray weakness of LRDs. We also find that THRILS LRDs are narrow-line dominated compared to literature AGN-dominated LRDs, and show that exponential profile fitting corrects for systematic overestimation of black hole masses from Gaussian-based measurements.
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All authors Ananya Ganapathy, Rebecca L. Larson, Erini Lambrides, Guillermo Barro, Taylor A. Hutchison, Pablo Arrabal Haro, Anthony J. Taylor, Dale Kocevski, Casey Papovich, Steven L. Finkelstein, Anton M. Koekemoer, Jonathan R. Trump, Pablo G. Pérez-González, Weida Hu, Volker Bromm, Dan Coe, Kelcey Davis, Michaela Hirschmann, Nikko J. Cleri, Ray A. Lucas, Stephan R. McCandliss, L. Y. Aaron Yung, Jorge A. Zavala
Astrophysics of Galaxies
A Novel Approach to 3D Dust Mapping of the Central Molecular Zone
Arianna Vasini, Mattia C. Sormani, Jason L. Sanders et al. (+12 more)
The 3D distribution of dust and gas in the Milky Way's Central Molecular Zone (CMZ) is key to understanding gas inflows toward the Galactic Centre (GC), the process of
star formation in this extreme environment, and the propagation of energetic
cosmic rays originating from Sgr A*. However, while recent efforts have combined
datasets in a
Bayesian framework to estimate the near/far positions of individual molecular clouds in the CMZ, conflicts between different methodologies still remain and we are still lacking a comprehensive, model-independent map of all of the gas and dust in the CMZ, which is critical to address key science questions. Here we develop a new methodology to infer the 3D dust distribution of the CMZ. The key idea of the method is to use stellar proper motions to get probabilistic information about the unknown stellar distances through a model of the distribution of
star positions and velocities of the nuclear stellar disc (NSD), co-spatial to the CMZ. Taking stellar proper motions and extinctions as input, the latter adopted as a proxy of the dust column density, the method returns the 3D dust distribution. It is non parametric, makes no a-priori assumption on the dust distribution, and is fundamentally distinct and largely independent of all existing methods. We show that the method can robustly and effectively reconstruct the mock 3D CMZ structure by testing it on a range of mock dust distributions, both analytically generated and taken from hydrodynamical simulations. Finally, we discuss the prospects for applying the method to real data.
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All authors Arianna Vasini, Mattia C. Sormani, Jason L. Sanders, Adam Ginsburg, Cara Battersby, Francisco Nogueras-Lara, Rainer Schödel, Eva Deliporanidou, Marco Donati, Zi-Xuan Feng, Karl Fiteni, Savannah Gramze, Xingchen Li, Dani R. Lipman, Perry H. Hatchfield
Astrophysics of Galaxies
BIND (Baryonic INpainting with Deep learning): A Field-level Emulator for Galaxy Groups and Clusters
Max E. Lee, Shy Genel, Zoltan Haiman et al. (+3 more)
Baryonic feedback is a dominant source of systematic uncertainty for upcoming weak-
lensing surveys, but current tools for modeling its effect rely on spherical approximations and density profiles calibrated almost entirely on two-point statistics. We introduce BIND (Baryonic INpainting with Deep learning), a conditional flow-matching model that learns a field-level mapping from dark-matter-only
halos to their hydrodynamical counterparts. BIND is trained on
halos from the 1024 paired hydrodynamical and dark-matter-only simulations of the CAMELS $50\,h^{-1}\,\mathrm{Mpc}$ SB35 suite and samples dark matter, gas, and stellar mass fields over
redshift across the full 35-dimensional $\Lambda$CDM and IllustrisTNG
galaxy formation parameter space. BIND recovers dark matter, gas, and stellar masses at the percent level, reproduces azimuthally averaged profiles to $\lesssim10\%$ at all radii, and matches
halo shape distributions with high fidelity. The learned parameter dependence captures the rank correlations between the generated fields and the subgrid parameters, and the field-level response to individual parameter variations is recovered in both sign and morphology.
Halo mass is never supplied as conditioning, yet the baryon fraction, stellar-to-
halo mass relation, inter-component scaling relations, and the joint covariance of their residuals are all reproduced. We finally show that, applied
halo-by-
halo to a $(50\,h^{-1}\,\mathrm{Mpc})^3$ $N$-body volume with $512^3$ particles, BIND reproduces the projected matter power spectrum suppression to the accuracy ceiling set by pasting in the hydrodynamical
halos themselves, in minutes on one GPU. We release the trained BIND models and all generated
halos as open-source tools. A companion paper extends BIND to thermodynamic fields and non-Gaussian weak-
lensing statistics.
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All authors Max E. Lee, Shy Genel, Zoltan Haiman, Greg L. Bryan, Christopher C. Lovell, Boryana Hadzhiyska
Astrophysics of Galaxies
Predictions for astrometric microlensing in Gaia
Zofia Kaczmarek, David Sweeney, Łukasz Wyrzykowski et al. (+1 more)
ESA's astrometric space mission Gaia is uniquely positioned for microlensing studies thanks to its all-sky coverage and simultaneous astrometric and photometric observations. In Gaia Data Release 4 (DR4), astrometric time series will be published for the first time, providing a rich
dataset for isolated stellar remnant searches. In anticipation of DR4, we prepared tools for fitting photometric and 1D astrometric measurements. We tested the recovery of true event parameters and population distributions with Gaia-like observations. We created a mock survey of microlensing events mirroring Gaia DR4's design. The events were generated using dedicated Galactic simulations to provide realistic expectations on stellar and dark lens yields. For selected events, we simulated observations following Gaia's scanning law and precision, using the astromet package. Such simulations are needed to interpret forthcoming data; they also enable testing inference tools with known ground truth. We used nested sampling to infer full posterior distributions and compare them with the true lens parameters. Our simulation predicts $322 \pm 70$ microlensing events with astrometric signals above Gaia precision thresholds; $209 \pm 57$ of them have detectable photometric signals. Among those, $82 \pm 9$ and $49 \pm 7$, respectively, have remnant lenses. To assess Gaia's capabilities in constraining remnant mass distributions, we modelled $49$ events from this sample. We recovered the true Einstein times and radii for most events. Microlensing parallax measurements are consistent with true values but uncertain, limiting mass determination. We recommend focusing on events with bright sources or anomalous fits to optimize dark lens searches. We make available the mock Gaia time-series
dataset, as well as a toolkit repository for working with the data format, fitting models, and visualizing results.
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All authors Zofia Kaczmarek, David Sweeney, Łukasz Wyrzykowski, Ulrich Bastian
Astrophysics of Galaxies
Probing dynamics of extreme galaxies I. Dark matter content in ultra-diffuse galaxies
Filippo Bouchè, Chiara Buttitta, Saboura Zamani et al. (+6 more)
We investigate the internal structure of two
galaxies from the LEWIS sample: the ultra-diffuse
galaxy UDG-1 and the extended dwarf LSB-6. Both show coherent stellar rotation combined with a non-negligible fraction of random motion, with no signs of ongoing disturbance. This is the first attempt to constrain the dynamics and dark matter physics of rotation-supported UDGs through integral-field stellar kinematics. We model the
galaxies as stellar spheroids with typical dwarf-like thickness embedded in spherical dark matter
halos, deriving two-dimensional velocity fields that we compare with the observations in a
Bayesian framework. Besides cold dark matter, we test fuzzy, self-interacting, and non-minimally coupled dark matter. The data prefer a cuspy
halo in UDG-1 and a cuspless one in LSB-6. All the alternative models remain viable, although current data cannot conclusively discriminate among them. For fuzzy dark matter we obtain mutually consistent
boson masses, $m_\alpha = 4.7^{+1.8}_{-1.1} \times 10^{-22}$ eV for UDG-1 and $m_\alpha = 6.3^{+0.4}_{-0.4} \times 10^{-22}$ eV for LSB-6. For self-interacting dark matter, LSB-6 yields a robust constraint on the velocity-weighted cross section, $\langle \sigma v\rangle/m = 14.3^{+2.0}_{-1.9}$ cm$^2$ km g$^{-1}$ s$^{-1}$. For non-minimally coupled dark matter we derive upper bounds on the coupling length, implying marginal deviations from $\Lambda$CDM. Regardless of the model, both
galaxies exhibit a dark matter content comparable with
halos of typical dwarf
galaxies with similar stellar masses. Together with stellar population analyses and globular cluster information, these results support a scenario in which UDG-1 and LSB-6 originate from puffed-up dwarfs. This work is the first in a series exploiting kinematic data of extremely low-surface-brightness
galaxies to test fundamental physics, from dark matter to modified theories of
gravity.
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All authors Filippo Bouchè, Chiara Buttitta, Saboura Zamani, Enrichetta Iodice, Salvatore Capozziello, Vincenzo Salzano, Marcello Miranda, Enrico Maria Corsini, Marco Mirabile
Astrophysics of Galaxies
Emulator-Assisted Calibration of a Semi-Analytic Galaxy Formation Model for the Roman Galaxy Redshift Survey
Andrew Robertson and Andrew Benson
Mock catalogues for the Roman
Galaxy Redshift Survey benefit from
galaxy populations whose physical properties and emission-line observables are predicted within a single
galaxy-formation framework. We present an emulator-assisted calibration of the semi-analytic model Galacticus for this purpose. Because direct posterior exploration with Galacticus is computationally prohibitive, we train Gaussian-process emulators to predict the observables entering the calibration likelihood. We calibrate the model simultaneously to stellar mass functions, the
star-formation-rate function, size–mass relations, the black-hole mass–velocity-dispersion relation, the mass–
metallicity relation, and H-alpha luminosity functions. Combining these observables breaks parameter degeneracies present in individual fits and can reveal tensions where different observables favour different regions of parameter space. The resulting model provides a broadly successful simultaneous description of the calibration data, including the abundance and
redshift evolution of H-alpha emitters relevant to the Roman
Galaxy Redshift Survey. A direct Galacticus calculation at the maximum a posteriori point gives similarly good agreement with the calibration data, providing a calibrated
galaxy-formation model suitable for constructing physically consistent mock catalogues for Roman.
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Astrophysics of Galaxies · Cross-listed from hep-ph
Implications of Inelastic Dark Matter for Primordial Dark-Star Evolution: Kinematic Thresholds and Nonthermal Capture
Qinxun Li and Shengyi Liu
The recent 248-keV nuclear recoil candidate reported by LUX-ZEPLIN has renewed interest in endothermic inelastic dark matter, motivating us to examine its capture in primordial dark
stars. Relative to the conventional elastic-capture picture in dark
star evolution, endothermic capture adds two qualitative features. First, it opens only after the growing
star crosses a compactness threshold, expressed as a kinematic radius $R_{\rm kin}\propto\mu_{\chi}M_\star/\delta$ set by the stellar mass, the dark-matter–
nucleus reduced mass and the mass splitting. The accreting growth carries the
star through the threshold, and the capture rate turns on quadratically above it. Second, although newly captured particles generically begin on nonthermal bound orbits, endothermic kinematics can keep this normally transient population spatially extended, turning it into a persistent reservoir rather than an intermediate step toward a thermal core. Following complete chains of state-changing collisions, we find that the reservoir compacts sharply and then stalls, because a ground state particle below a compactness-dependent orbital energy has no allowed up-scatter anywhere in the
star. A percent-level radius contraction reopens the relaxation. These kinematic results do not depend on whether the excited state decays promptly or is long-lived. As a result, inelastic capture does not replenish a thermal annihilation core. The captured population forms an evolving orbital distribution that sets up the co-evolutionary dynamics between the
star and the dark matter in the core and the reservoir, which we develop in a companion paper.
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Astrophysics of Galaxies
The kinematics of tadpole galaxies at intermediate redshift $z \sim 0.4 - 1.5$
Manish Kataria, Kanak Saha and Bruce Elmegreen
Galaxy morphology and kinematics encode complementary information about the assembly history of
galaxies, but the extent to which they evolve in tandem remains unclear. Tadpole
galaxies, characterized by their distinct head-tail morphology and pronounced asymmetry, provide an ideal laboratory for investigating whether strongly asymmetric
galaxies can exhibit ordered
galaxy-scale kinematics. In this work, we present a detailed analysis of the ionized-gas kinematics of 20 morphologically selected tadpole
galaxies at
redshifts $z=0.4 - 1.5$ in the Hubble Ultra Deep Field, using deep VLT/MUSE spectroscopy together with HST and JWST imaging. In 13 out of 20
galaxies, the 2D velocity maps derived from the MUSE [O\,ii] $\lambda\lambda3726,3729$ emission show evidence for ordered motion, characterized by moderate velocity gradients along the kinematic major axis, while the remaining systems show no clear evidence for
galaxy-scale ordered kinematics. In 16
galaxies, the [O\,ii] and rest-frame optical emission, probed by HST/F775W, have spatially coincident centroids, with projected offsets of $<2$~kpc. The morpho-kinematic position angles are also generally well aligned, with a median misalignment of $\Delta{\rm PA}\sim12^{\circ}$. Despite the strongly asymmetric tadpole morphologies, these results indicate that a substantial fraction of these systems retain coherent
galaxy-scale gaseous kinematics, suggesting that morphological asymmetry need not imply a globally disordered dynamical state. Together, our analyses suggest that morphological and kinematic settlement does not occur simultaneously and these tadpole
galaxies might represent a transient evolutionary phase towards the combined morpho-kinematic settlement process.
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Astrophysics of Galaxies
ACES VIII: A Survey of Compact, High-Velocity Features Observed in CS(2-1)
Dani R. Lipman, Jakub Poznanski, Savannah R. Gramze et al. (+45 more)
The extreme kinematics of the Milky Way's Central Molecular Zone (CMZ) are influenced by processes such as dynamical shearing, cloud collisions, and stellar feedback. These events are visible in molecular data as vertically spiked features in position-velocity (PV) diagrams referred to as high velocity dispersion compact clouds (HVCCs). Using ALMA CMZ Exploration Survey (ACES) CS (2-1) molecular data, we identify a total of 235 HVCC candidates, 163 of which are visually identified, and an additional 72 identified via automated dendrogram methods. For each HVCC we catalog and report the physical and kinematic properties, explore line ratios of the cold dense gas tracer \HNCO with C-shock tracers, classify the morphology of their PV diagrams, and view their position-position-velocity distribution. The sample includes structures which are compact (d<5 pc) and have large velocity extents (20 km/s $<\Delta \mathrm{V} <$ 140 km/s), with most structures showing thin, `spiked' PV morphologies. We highlight areas of high ratios between HNCO and C-shock tracers along the edge of known orbital streams, implying a buildup of bar lane gas accreting onto the CMZ. We also find a collection of HVCCs overlapping with the 50 km/s cloud and known circumnuclear disk features. This catalog will be used for future investigation of nuclear inflow and determining dominant mechanisms disrupting average CMZ gas flows.
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All authors Dani R. Lipman, Jakub Poznanski, Savannah R. Gramze, Claire E. Cook, Cara Battersby, Jennifer Wallace, Pablo García, Samantha Adams, Xinyu Mai, Kai Smith, Natalie Butterfield, Sophia Kempe, Adam Ginsburg, Rojita Buddhacharya, Tomoharu Oka, Jairo Armijos-Abendaño, John Bally, Ashley T. Barnes, Nazar Budaiev, Alyssa Bulatek, Laura Colzi, Christoph Federrath, Zi-Xuan Feng, Jonathan D. Henshaw, Paul Ho, Pei-Ying Hsieh, Katharina Immer, Izaskun Jiménez-Serra, Ralf S. Klessen, Steven N. Longmore, Xing Lu, Elisabeth A.C. Mills, N. Bijas, Francisco Nogueras-Lara, Dylan M. Paré, Maya A. Petkova, Jaime E. Pineda, Marc W. Pound, Víctor M. Rivilla, Álvaro Sánchez-Monge, Miriam G. Santa-Maria, Anika Schmiedeke, Yoshiaki Sofue, Mattia C. Sormani, Howard A. Smith, Robin G. Tress, Daniel Walker, Qizhou Zhang
Astrophysics of Galaxies
Extending the Little Red Dot population at intermediate redshift with VIPERS
Krzysztof Lisiecki, Krzysztof Hryniewicz, Francesco Pistis et al. (+7 more)
Little red dots (LRDs) are a recently identified population of compact, red sources characterised by a distinctive V-shaped UV-to-optical continuum and broad emission lines. Their physical structure and
evolution remain uncertain, while their properties at intermediate
redshifts are largely unexplored. We identify and characterise LRD-like sources at 0.5<z<1.75 using the VIMOS Public Extragalactic
Redshift Survey (VIPERS), extending observational studies to a previously poorly explored
cosmic epoch. We select candidates from their UV and optical slopes measured from broadband photometry and refine the sample using broad emission lines in VIPERS spectroscopy. We investigate their photometric, spectroscopic, and morphological properties, constrain their physical sizes with HSC imaging, measure their comoving number density and
evolution, and characterise their local environments using the VIPERS
galaxy density field. We also model the multi-wavelength emission of the unique X-ray-detected source with CIGALE, including X-ray and AGN emission. We identify 14 LRD-like sources, including one X-ray-detected object, whose HSC morphology remains unresolved. We measure their number density in two
redshift bins, 0.5<z<1 and 1<z<1.75, and combine our results with literature measurements. We find a rapid decline in number density after
cosmic noon. The two sources with sufficiently constrained environments are located in underdense regions. The SED of the X-ray-detected source is best reproduced by a radiatively efficient
accretion disk viewed at low inclination. Our results demonstrate that LRD-like sources are present at z>0.5, bridging local and high-
redshift studies. Their abundance, compact morphology, environmental properties, and multi-wavelength emission provide new constraints on the
evolution and physical origin of this population.
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All authors Krzysztof Lisiecki, Krzysztof Hryniewicz, Francesco Pistis, Michał J. Michałowski, Aidan P. Cotter, Maciej Koprowski, Miguel Figueira, Agnieszka Pollo, Katarzyna Małek, Olga Cucciati
Astrophysics of Galaxies
From stardust to interstellar grain growth in the first galaxies: a cosmological transition in dust evolution near z ~ 8.9
Denis Burgarella, Tom J. L. C. Bakx, Raffaella Schneider et al. (+7 more)
When and how did dust begin to shape
galaxies? Motivated by the identification of an apparent
redshift break in
galaxy dust masses, suggesting substantially lower dust masses at $z \gtrsim 9$, we investigate dust enrichment during the first billion years of
cosmic history. We aim to determine whether the observed
evolution marks a transition in the dominant dust-production mechanism and to identify the physical conditions under which such a transition is expected to occur. Using JWST, ALMA, and NOEMA observations, we measure ultraviolet dust attenuation and dust masses. We apply a censored change-point analysis and compare the observations with dust
evolution modelling. The analysis identifies a preferred transition near
redshift z ~ 8.9, corresponding to about 570 Myr after the Big Bang. The evidence for a break is strongest in dust mass and dust-to-stellar mass ratio, mostly estimated from JWST NIRSpec spectrophotometric fitting but also partly from sub-mm data. The ultraviolet attenuation measurements are consistent with a transition at the same epoch but do not independently require one. The models are consistent with the onset of efficient interstellar grain growth above a characteristic
metallicity. We interpret the transition near z ~ 8.9 as the emergence of grain-growth-dominated dust
evolution from an earlier regime dominated by
supernova-produced grains. Population III enrichment can modify the earliest chemical-enrichment history but leaves the timing of the dust transition nearly unchanged and is not required for its emergence.
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All authors Denis Burgarella, Tom J. L. C. Bakx, Raffaella Schneider, Hiddo S. B. Algera, Chloe Aurin, Tim Dewachter, Clarke Esmerian, Luca Graziani, Kirsten Knudsen, Koki Otaki
Astrophysics of Galaxies · Cross-listed from astro-ph.HE
Associating binary black holes with galactic centres using lensed gravitational waves
Laura Uronen, Tian Li, Qiuhan He et al. (+4 more)
Binary black holes (BBHs) have been theorised to form through various different channels, but current LIGO-Virgo-KAGRA (LVK) sky locations make the direct study of formation channels a challenge. Association of strongly lensed BBHs to their hosts has been shown to be possible with current detector networks at upgraded sensitivity and survey
telescopes like Euclid, with localisations that can reach sub-galactic scales in the source plane. With Hubble Space
Telescope-like high-resolution imaging, we report that strong-
lensing localisation of BBHs allows us to confidently associate the BBH with specific structures within their host
galaxies, specifically, galactic centres (GCs). We demonstrate that a BBH localised to the GC of the
galaxy can reject light-tracing BBH populations ($p < 5\%$) in a single observation, and in most cases demonstrate high confidence rejection ($p < 1\%$), providing a conservative basis to exclude light-tracing spatial distributions associated with field-like or non-central formation channels. Such association therefore directly supports formation channels confined to GCs, such as active galactic
nuclei and nuclear stellar clusters.
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All authors Laura Uronen, Tian Li, Qiuhan He, Justin Janquart, Thomas Collett, Léon V.E. Koopmans, Otto Hannuksela
Astrophysics of Galaxies
Cosmic-ray electron propagation in the peculiar barred spiral galaxy NGC 2442
Shengtao Wang, Xiaohui Sun, Volker Heesen et al. (+13 more)
Face-on spiral
galaxies offer a favorable geometry for studying
magnetic-field structures and
cosmic-ray (CR) propagation because projection effects and structural overlap are reduced. We investigate
cosmic-ray electron (CRE) transport in the nearby face-on spiral
galaxy NGC 2442 and assess how its environment and
magnetic-field structure influence propagation. We combine
radio continuum (RC) observations from ASKAP at 943 MHz, MeerKAT at 1.28 and 1.7 GHz, and ATCA at 5 GHz with optical H$\alpha$ and infrared data, and compare them with 2D CRE transport simulations. NGC 2442 has a steep integrated RC spectrum, with $\alpha=-0.96\pm0.04$ for the total emission and $\alpha_{\rm nt}=-1.21\pm0.04$ for the synchrotron emission over 408 MHz-5 GHz. A break near 1 GHz indicates substantial radiative aging. Under equipartition, we derive a mean
magnetic-field strength of $10.8\,\mu{\rm G}$. RC-SFR smoothing gives effective CRE propagation lengths of $\sim0.65$-$0.89$ kpc at 943-1700 MHz and $\sim0.44$ kpc at 5 GHz, corresponding to
diffusion coefficients of order $10^{28}\,{\rm cm^2\,s^{-1}}$. We identify a steep-spectrum synchrotron “island” in the southeast, with $\alpha\sim-1.09$ and no clear H$\alpha$, infrared, FUV, or NUV counterpart, indicating that CREs are unlikely to be injected in situ. Our 2D CRPropa simulations show that anisotropic
diffusion along ordered
magnetic fields enables CREs to reach the island more efficiently than isotropic
diffusion. NGC 2442 therefore shows that environmental disturbances and ordered
magnetic fields can strongly regulate CRE propagation in disturbed spiral
galaxies.
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All authors Shengtao Wang, Xiaohui Sun, Volker Heesen, George Heald, Jiangtao Li, Chao-Wei Tsai, Stefan W. Duchesne, Andrew J. Battisti, Yik Ki Ma, Amit Seta, Jun Xu, Naomi McClure-Griffiths, Christopher J. Riseley, Sam Taziaux, Jacco Th. van Loon, Tayyaba Zafar
Astrophysics of Galaxies
The solar Galactocentric distance and local kinematic parameters from Gaia DR3 using Bottlinger's equations
D. V. Odynets, V. S. Akhmetov and S. I. Denyshchenko
The solar Galactocentric distance, $R_0$, together with the local kinematic parameters of the Milky Way, provides fundamental constraints on the Galactic structure and rotation. Their accurate determination has become possible with the hight astrometric precision of Gaia DR3 catalogue. We determine the Galactocentric distance, the Solar peculiar motion components $(u_0,v_0,w_0)$, and the local angular velocity of Galactic rotation, $\omega_0$, using a self-consistent approach based on Bottlinger's equations within a nonlinear least-squares framework. Bottlinger's equations were applied to approximately 13 million luminous giant
stars $(M_G<4)$ selected from Gaia DR3. The analysis was carried out for two subsamples: a thin disk dominated sample (|z|<0.5 kpc) and a mixed thin and thick disk sample (|z|<1.0 kpc). The kinematic parameters were estimated using a nonlinear generalized least-squares method. We obtained $R_0=8.165\pm0.024$kpc and a local angular velocity of Galactic rotation $\omega_0=28.477\pm0.002$ km/s/kpc for the thin disk dominated sample. The Solar peculiar motion components are $(u_0,v_0,w_0)=(9.261\pm0.006,16.593\pm0.008,7.686\pm0.008)$km/s. Including mixed thin and thick disk
stars resulted in a systematic shift in $R_0$, yielding $R_0=8.333\pm0.022$kpc, while the Solar peculiar motion and local angular velocity remain consistent within uncertainties. The Galactic kinematic parameters derived are consistent with recent independent determinations. The Solar peculiar motion parameters and the local angular velocity remain stable for different vertical selections, the recovered Galactocentric distance exhibits a systematic dependence on the adopted stellar sample, indicating that the vertical structure of the tracer population should be taken into account when determining $R_0$.
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Astrophysics of Galaxies
The internal kinematics and chemistry of 20 Milky Way strings
C. Boeche, A. Vallenari, J. Alonso-Santiago et al. (+8 more)
Context: the recent discovery of filamentary stellar structures in the Milky Way disk raises the question of their formation in the context of the
Galaxy evolution. Aims: in this work, we aim to kinematically and chemically characterize several filamentary stellar structures by looking for clues about their origin and formation mechanism. Methods: recent works using machine-learning techniques and $Gaia$ data have identified many previously unknown Galactic strings. We cross-matched such data with the kinematics derived from the most recent Gaia DR3 catalog as well as chemical data provided by the Galactic Archaeology with HERMES (GALAH) survey. Results: we found that most strings contain one or more open clusters and are kinematically hotter than open clusters (with internal velocity dispersions in the 1–7 km/s range) but cooler than field
stars. 18 objects appear chemically homogeneous ($\sigma_{[Fe/H]}$ <= 0.1 dex), while two strings have a broad [Fe/H] distribution similar to the field
stars but exhibit a different mean
metallicity, which may identify them as migrating stellar structures. For seven objects the GALAH observations focus on the embedded open clusters; therefore, the chemical abundances are not representative of the whole structure. An object shows clues of chemical gradients along its extension in Galactic longitude. Conclusions: these objects may be evaporating or disrupted open clusters in which the chemical homogeneity is preserved in an unbound and expanding cloud of
stars or co-moving
stars belonging to a former and now disrupting
star formation hub. In a few cases they appear to be moving groups with no chemical homogeneity, likely formed by the dynamical action of the Galactic bar or spiral arms. More data are needed to confirm such hypotheses.
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All authors C. Boeche, A. Vallenari, J. Alonso-Santiago, A. Bragaglia, R. Carrera, E. Dalessandro, E. Carretta, E. Franciosini, A. Frasca, S. Lucatello, G. Andreuzzi
Astrophysics of Galaxies · Cross-listed from astro-ph.IM
Enabling New Discoveries with Machine Learning
Michelle Lochner
The next generation of
telescopes such as the Square Kilometre Array and the Vera C. Rubin Observatory will produce enormous quantities of data, too large for traditional analysis techniques. Machine learning has proven invaluable in handling massive data volumes and automating tasks traditionally done by human scientists. The question is, can machine learning also automate scientific discovery? Recent advances in the field have made this feasible but only when combined with expert human input through active learning. Astronomaly is a publicly available framework for active anomaly detection in astronomy. It learns to make recommendations of interesting sources to a user, allowing scientists to quickly uncover rare and new classes of objects in large
datasets. In this paper, we review some of the discoveries made using Astronomaly, discuss the latest deep learning-based approaches and explore the critical role of the cyber-human interface in unveiling
cosmic mysteries hidden in massive astronomical
datasets.
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Astrophysics of Galaxies
The JWST Emission Line Survey (JELS): Multi-wavelength properties of Paschen line-emitters at Cosmic Noon
Malte Brinch, Edo Ibar, Luis Ossa-Fuentes et al. (+14 more)
Context: Narrowband JWST/NIRCam selection isolates
star-forming
galaxies in well-defined
redshift slices, while ALMA and archival far-IR/submm data reveal obscured growth. We combine these to measure Paschen-line SFRs, infer nebular extinction from EAZY Av, and probe FIR-to-submm emission via weighted-median stacking, to constrain
galaxy growth at
cosmic noon. Aims: We characterize stellar, nebular, and FIR properties of Paschen-selected
galaxies in COSMOS, in two ensembles at z~1.50 (Pa-alpha) and z~2.65 (Pa-beta), quantifying short- vs long-timescale SF and dust attenuation, and constraining obscured SFR and gas masses. Methods: We select robust narrowband-excess samples from the JELS F466N/F470N mosaic (Pa-alpha: 77, Pa-beta: 31 sources), remove AGN via X-ray/
radio matching, and assemble multiwavelength photometry (JWST, HST, Spitzer, Herschel, SCUBA-2, AzTEC, ALMA). Photo-z/stellar properties come from EAZY/STARDUST; line SFRs use recent Paschen calibrations, with nebular extinction from EAZY Av. Results: EAZY fits show stellar masses log(Mstar/Msun)~7.4-10.3 and modest SFRs (0.1-27 Msun/yr). Line SFRs are 0.1-22.0 and 0.7-47.9 Msun/yr for Pa-alpha/beta. Most sources show short-term bursts (line SFRs exceed SED SFRs), weakly decreasing with mass. Nebular attenuation correlates with mass and SFR. Stacking gives no >3sigma detections beyond MIRI. The weighted-median SED gives SFR_UV,med = 0.48+-0.11 and 3.92+-0.47 Msun/yr for Pa-alpha/beta. ALMA Band 4 gives the tightest constraints: median 3-sigma limits SFR_IR<53 (Pa-alpha) and <44 Msun/yr (Pa-beta); gas mass <10^11.2 (Pa-alpha) and <10^10.6 Msun (Pa-beta). Conclusions: Paschen-selected samples show widespread short-timescale
star formation, but FIR/sub-mm data give only upper limits on obscured SFR/ISM mass. Deeper spectroscopy and ALMA continuum data are needed to constrain obscured SF and gas reservoirs.
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All authors Malte Brinch, Edo Ibar, Luis Ossa-Fuentes, Corey Pirie, Philip Best, R. K. Cochrane, Kenneth Duncan, James Dunlop, Sophia Flury, Catherine Hale, Jorryt Matthee, Derek McLeod, Joshua Selfridge, David Sobral, Harry Stephenson, J. P. Stott, A.M. Swinbank
Astrophysics of Galaxies · Cross-listed from astro-ph.HE
Search for refractive substructure in active galactic nuclei using ground-based VLBI observations
Tatiana A. Koryukova, Alexander V. Plavin, Alexander B. Pushkarev et al. (+1 more)
We present the results of the first systematic search for refractive scattering substructure in active galactic
nuclei (AGN) using ground-based very long baseline interferometry (VLBI) data. We selected 1074 AGNs showing a steep frequency dependence of their angular sizes and compared the observed long-baseline visibility amplitudes with the predictions of the refractive substructure model for scatter-broadened images. Nine sources showed consistency with the expected level of refractive noise, including the
quasar TXS 2005+403 (J2007+4029), which confirms previously reported results for this source. Remarkably, the majority of these AGNs are located in the Cygnus region – one of the key “hotspots” of strong Galactic scattering. For five selected AGNs, we identified at least two epochs with sufficiently high data quality showing long-baseline detections, suggesting the presence of scattering substructure. We showed that refractive scattering substructure in AGN is a rare effect, requiring high sensitivity, sufficient source brightness, and lines of sight with particularly strong
turbulence in the interstellar medium. Nevertheless, AGNs can serve as powerful probes of the turbulent interstellar medium. We discuss strategies for improving the sensitivity of VLBI observations and identify the most promising sources for reliable detection and investigation of refractive substructure in future observations.
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All authors Tatiana A. Koryukova, Alexander V. Plavin, Alexander B. Pushkarev, Yuri Y. Kovalev
Astrophysics of Galaxies
Milky Way Structure from Double White Dwarf Gravitational-Wave Sources
Shao-Dong Zhao, Xue-Hao Zhang, Qun-Ying Xie et al. (+2 more)
The millihertz gravitational-wave sky will be dominated by $\sim10^{8}$ double white dwarfs while $\sim10^{4}$ be resolvable in the Milky Way, whose three-dimensional spatial distribution traces the
Galaxy's structural parameters. We present Galena, a hierarchical
Bayesian pipeline that recovers these parameters from a double white dwarf catalogue through an inhomogeneous Poisson-process likelihood. Each source's $3\times3$ Galactic position covariance is computed from the waveform Fisher information
matrix and propagated analytically through a $3\times5$ Jacobian; the resulting measurement-error convolution is factored into a pre-computed sparse weight
matrix, rendering the nested-sampling inference tractable. Applied to GBSIEVER-reported LISA Data Challenge sources ($N=2151$ after quality cuts), Galena recovers the disk scale length $R_d=2175^{+51}_{-52}$~pc and scale height $z_d=282^{+7}_{-7}$~pc, consistent with a canonical thin disk, together with the bulge fraction $A=0.187^{+0.011}_{-0.012}$ and bulge scale radius $R_b=773^{+26}_{-25}$~pc; the bulge fraction, now recovered much closer to the literature value of $0.25$ than in our earlier exact-position fit, is measured at $\sim6\%$ statistical precision. An independent particle-swarm optimisation of the same likelihood reproduces these values to within a fraction of a percent, supporting the attribution of the improvement to the Fisher-
matrix error propagation rather than to the sampler. The search-stage astrophysical prior improves per-source distance estimates but leaves the hierarchical inference essentially unchanged.
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All authors Shao-Dong Zhao, Xue-Hao Zhang, Qun-Ying Xie, Yu-Xiao Liu, Soumya D. Mohanty
Astrophysics of Galaxies · Cross-listed from astro-ph.SR
Long-slit spectroscopy of the bipolar planetary nebula ESO\,428$-$05
Alexei Kniazev
The results of detailed long-slit spectroscopy of the bipolar planetary nebula \ESO\ are presented. The observations were obtained with the facility spectrograph RSS of the SALT
telescope. The total measured extent of the nebula reaches $\approx$55$^{\prime\prime}$, and the kinematics along the slit directly confirms its bipolar structure. The inclination of the nebula to the line of sight is estimated as $i\approx 45^{\circ}$, and the kinematic ages of two morphological structures are measured: the expanding ring and the polar outflow in the direction perpendicular to the ring. The age of the former is $\approx$1.5$\times$10$^4$~yr and that of the latter is $\approx$(3–4)$\times$10$^4$~yr, i.e. the polar outflow is 2–3 times older than the central ring. The ratio of these ages does not depend on the adopted distance. The weighted mean heliocentric velocity of \ESO\ is V$_{\rm hel}$=74.7$\pm$1.6~\kms. Chemical abundances are obtained for 19 regions along the major axis of the nebula, over an extent of 40$^{\prime\prime}$, i.e. for different morphological parts of \ESO. The abundances were derived with the T$_{\rm e}$–method, where the electron temperature was calculated directly using the measured faint auroral lines [\ion{O}{iii}]~$\lambda$4363~Å\ and [\ion{N}{ii}]~$\lambda$5755~Å. The abundances of O, N, Ne, S, Ar, Cl and He were determined. Despite a significant stratification, the measured abundances along the slit can be considered nearly constant.
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Astrophysics of Galaxies
The magnetic field in M16: new results from the JCMT BISTRO survey
R.M.R. Tulloh, D. Ward-Thompson, J. Karoly et al. (+2 more)
We present a study of the
magnetic field (B-field) in the Eagle Nebula (M16) using data from the James Clerk Maxwell
Telescope (JCMT) B-fields In
STar-forming Region Observations (BISTRO) survey. We extend our previous study of the well-known `Pillars of Creation' region of the nebula to study two other structures in the region, the `Spire' and the bright-rimmed cloud (BRC) known as `SFO30'. These structures show similar B-field morphologies to the Pillars. We calculate B-field strengths using the Davis-Chandrasekhar-Fermi (DCF) method and thereby estimate the
magnetic potential energy in each of these regions for comparison with the local gravitational, turbulent and thermal energies, as well as the pressure energy of the shocks from nearby O-type
stars. We find approximate equipartition between the energies supporting the regions and those tending towards collapse, with the B-field support playing a significant role. This agrees with our earlier hypothesis that B-fields help support pillar-like structures in molecular clouds and make them longer-lived than they would otherwise have been.
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All authors R.M.R. Tulloh, D. Ward-Thompson, J. Karoly, J.M. Kirk, K. Pattle
Astrophysics of Galaxies
The Dense Gas Structures Around MMS 2/OMC-3 Traced by C$^{18}$O Emission
Yuhua Liu, Satoko Takahashi and Masahiro N. Machida
We report the Atacama Large Millimeter/submillimeter Array observations of 1.3 mm continuum, C$^{18}$O ($J=2$$-$$1$), and N$_{2}$D$^{+}$ ($J=3$$-$$2$) toward the millimeter multi-system MMS 2 in the Orion Molecular Cloud-3 region, at an angular resolution of 1.59" ($\sim$620 au). MMS 2 is in the flat-spectrum phase, with its protostars in the late stage of the main
accretion phase. We detect the centrally condensed structures traced by C$^{18}$O emission associated with the 1.3 mm continuum sources MMS 2-North and MMS 2-South, which are spatially resolved and unresolved, respectively. The estimated diameter and mass of the centrally condensed structure associated with MMS 2-North are 1.64" ($\sim$640 au) and 3.0$\times$10$^{-4}$M$_{\odot}$, respectively. We also detect an extended structure traced by C$^{18}$O emission associated the circumbinary envelope at scale of 5.70" ($\sim$2240 au) with an estimated gas mass of 1.4$\times$10$^{-2}$$M_{\odot}$. In addition, we detect a filamentary structure traced by N$_2$D$^+$ emission to the south of MMS 2, which is spatially offset from the C$^{18}$O emission. This offset may be attributed to the influence of the warm surrounding environment.
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Astrophysics of Galaxies
A Theoretical Study of the Stellar Parameters and Surface Nucleosynthesis of the Extremely Metal-Poor RGB Giant BD$-18^{\circ}$5550 - Part I: Effects of $\alpha$-enhancement and Internal Mixing
Mrinmay Medhi, Upakul Mahanta, Swapnajyoti Sarma et al. (+1 more)
We present a detailed stellar
evolution study of BD$-18^{\circ}$5550, an extremely metal-poor red giant
star in the Galactic
halo. Such
stars are among the oldest known objects and preserve chemical signatures of the earliest stages of Galactic history. BD$-18^{\circ}$5550 exhibits $\alpha$-enhancement, $\rm[\alpha/Fe]=+0.4$, typical of Population II
halo stars, with enhanced abundances of oxygen, magnesium, and other $\alpha$-elements relative to iron. Using the MESA stellar
evolution code, we perform the first direct determination of its mass, age, radius, and luminosity by simultaneously fitting eight observed stellar properties and multiple chemical abundance ratios. Our analysis yields a current mass of $\rm M=0.76,M_{\odot}$, radius of $R=38.4,R_{\odot}$, luminosity of $\log L=2.8,L_{\odot}$, and an age of $t=11.87$ Gyr, with a 7-fold improvement in age precision. The model reproduces all observed constraints, supporting our treatment of stellar physics, nuclear reactions, and internal mixing. We further investigate the predicted surface chemical composition up to iron and compare it with observations. The surface abundances of elements up to iron remain essentially unchanged throughout the
evolution, while nitrogen shows gradual enrichment, indicating the onset of mixing processes at intermediate RGB stages. The preservation of the other surface abundances provides a valuable window into the chemical conditions of the early Galactic environment. Our results establish BD$-18^{\circ}$5550 as a
benchmark star for constraining stellar
evolution and early Galactic chemical
evolution. Its derived age places it among the oldest
stars in the Milky Way, providing important constraints on the epoch of early
star formation and the initial assembly and
evolution of our
Galaxy.
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All authors Mrinmay Medhi, Upakul Mahanta, Swapnajyoti Sarma, Apurba Talukdar
Astrophysics of Galaxies
Tracing M22's origins: Spatial and chemical constraints on its formation history
Emanuele Dondoglio, Antonino P. Milone, Randa Asa'd et al. (+9 more)
Globular clusters (GCs) are well known to host stellar populations characterized by light-element variations. A subset of Galactic GCs, beyond such 'canonical' populations, contains an additional group enriched in iron, s-process elements, and total C+N+O abundance (i.e., the anomalous
stars). We combine multi-facility photometry with APOGEE spectroscopy to investigate the spatial distribution, chemical properties, and formation history of the stellar populations in M22, with particular focus on its anomalous component. We trace the canonical and anomalous populations, together with their subpopulations, from the cluster center out to eight half-mass radii. The anomalous population becomes increasingly dominant in the outermost regions, whereas no significant radial gradients are detected among its subpopulations. Our chemical analysis reveals light-element anticorrelations within both the canonical and anomalous components, although the latter are shifted toward higher C, N, and Al abundances. For the first time, we show that the Fe, s-process, and C+N+O enhancements among anomalous
stars are not uniform but correlate with their light-element composition: the most chemically extreme anomalous
stars are also the most Fe-, Ce-rich, and C+N+O-poor. We identify a distinct red overdensity on the horizontal branch, likely populated by the most He-poor
stars, and tentatively associate the extreme horizontal branch with the most chemically enriched anomalous population. These observations are difficult to reconcile with M22 being a merger between two GCs. Instead, they qualitatively favor a self-enrichment scenario regulated by dilution, similar to that recently proposed for $\omega$Centauri, with their close chemical correspondence suggesting that they experienced analogous formation histories.
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All authors Emanuele Dondoglio, Antonino P. Milone, Randa Asa'd, Anna F. Marino, Alessandra Mastrobuono-Battisti, Fabrizio Muratore, Tuila Ziliotto, Emanuele Bortolan, Giacomo Cordoni, Maria Vittoria Legnardi, Edoardo P. Lagioia, Marco Tailo
Astrophysics of Galaxies
CROCODILE-SIDM: Tidal Formation of Dark Matter-Deficient Galaxies as a Test Case
Kenji Kihara, Kentaro Nagamine, Lissandre Bourrat et al. (+3 more)
We introduce CROCODILE-SIDM, a framework for treating self-interacting dark matter (SIDM) with the $N$-body part of GADGET4-Osaka code, as part of CROCODILE simulation family. As a test case, we investigate the impact of SIDM on the tidal formation of dark matter-deficient
galaxies (DMDGs) with velocity-dependent cross-section models. We demonstrate that our implementation reproduces the analytic scattering rate in isolated
halos. Including dynamical friction self-consistently, we evolve a dwarf satellite with $M_*=2\times10^8\,\mathrm{M}_\odot$ in a $\sim10^{11}\,\mathrm{M}_\odot$
halo on a decaying orbit around a massive host, comparing CDM with four SIDM cross sections for two initial satellite density profiles: a cuspy Navarro–Frenk–White (NFW) profile and a cored Burkert profile. We find that self-interactions primarily regulate the amount of DM retained between pericentric passages, and that the sign of this effect depends on the initial profile: a larger cross section retains more DM for the Burkert initial condition but less DM for the NFW initial condition. We show that this opposing behavior reflects the direction of SIDM heat conduction, which is set by the
halo's evolutionary state at infall. Core formation in the cuspy profile assists DM stripping, whereas tidally accelerated gravothermal contraction in the cored profile suppresses tidal mass loss. Consequently, SIDM can either assist or hinder DMDG formation, depending on the satellite's inner structure, making DMDGs a potential probe of SIDM cross section.
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All authors Kenji Kihara, Kentaro Nagamine, Lissandre Bourrat, Leonard Romano, Yuri Oku, Daisuke Toyouchi