arXiv subjects

Christine Jones

Publications and source records attributed to Christine Jones.

At least 19 recordsLinked to original sources

arXiv2026

A Swift X-ray view of the SMS4 sample - III: Deeper insight into previously undetected sources

We update the X-ray information given in Maselli et al. (2024) for five bright radio sources in the SMS4 catalog, thanks to additional observations with the X-Ray Telescope (XRT) on board the Neil Gehrels Swift Observatory (hereafter Swift) carried out through February 2026. X-ray emission from MRC B1754-597, previously based only on data from the eROSITA-DE DR1 catalogs, is now detected also by Swift, which yields a more precise positional uncertainty. Thanks to ~7 ks of additional exposure with Swift we are now able to detect MRC B1817-391, a source for which no X-ray counterpart is found in eROSITA-DE DR1. Another source that is not detected in the eROSITA-DE DR1 catalogs, and that was not observed by Swift earlier than 2025, is MRC B1827-360: with a ~6 ks X-ray observation, the source is detected. Finally, based on ~8 ks of additional exposure, we detect X-ray emission for MRC B2032-350, a source that lies out of the DR1 footprint. In contrast, additional exposure (~2 ks) just gives an upper limit on the X-ray emission of MRC B1814-519. The analysis of the extent and the hardness ratio of the four detected X-ray sources suggests the presence of soft, diffuse X-ray emission as expected from galaxy group cores or hot galaxy coronae. Using the positional uncertainty of the X-ray detections to constrain the search for counterparts at lower energies, we provide a new infrared/optical counterpart for MRC B1817-391 and confirm the counterparts previously reported in the literature for the three remaining sources.

astro-ph.HE↗

arXiv2026

Kinematics of Weak Cool-Core Cluster A3571 Observed with XRISM: Low Cooling Rate Balanced by Low Heating Rate

Most XRISM galaxy cluster observations to date have focused on AGN feedback or actively merging systems. The weak cool-core cluster A3571 was observed in four XRISM Cycle 1 pointings, enabling the study of gas kinematics in a relaxed, AGN-feedback-free system. We present measurements of the velocity dispersion and bulk velocity in the core regions of A3571, out to $120$ kpc. The velocity dispersion is relatively uniform across all regions ($\sim100-120 ~\mathrm{km~s^{-1}}$), except in the northern gas sloshing elongation, where a $68\%$ upper limit of $68~\mathrm{km~s^{-1}}$ is obtained. The core Mach number and non-thermal pressure fraction of A3571 are lower than in the extremely relaxed cluster A2029 and below predictions from cosmological simulation suites. Despite relatively low velocity dispersion values, the derived turbulent heating rate is sufficient to offset cooling losses in all studied regions. This suggests that sloshing motions contribute significantly to the heating budget. Comparing XRISM observations of merging and relaxed clusters, we find that mergers exhibit an average Mach number of $0.29\pm0.07$, nearly twice that of the relaxed sample, which is consistent with predictions from non-radiative cosmological simulations. A3571 is a promising target for resonant scattering studies; however, simulations indicate that deeper observations are required to obtain reliable turbulent velocities via the $z/w$ line ratio.

astro-ph.GA↗

arXiv2026

Sloshing Motions in Abell 3571 Revealed by XRISM/Resolve Velocity Mapping

Minor mergers can induce sloshing motions in the intracluster medium, leaving characteristic signatures in the thermodynamic structure and gas kinematics of cluster cores. Abell 3571 is an X-ray-bright, apparently relaxed cluster at $z \sim 0.04$. We observed the central $\sim 300$ kpc region of Abell 3571 with four partially overlapping XRISM Resolve pointings, covering three contiguous Resolve fields to the north, south and east with a total exposure time of approximately 575 ks. The velocity dispersions are subsonic and are at the level of $\sim 100$--$150 \, \mathrm{km~ \, s^{-1}}$ across most regions. The cooler region associated with the northern surface-brightness excess is blueshifted by up to $\sim -60 \, \mathrm{km \, s^{-1}}$ relative to the brightest cluster galaxy (BCG), while the hotter region in the southern and eastern surface-brightness deficit regions is redshifted by up to $\sim 170 \, \mathrm{km \, s^{-1}}$. Numerical simulations suggest that this large-scale thermodynamic and kinematic asymmetry is broadly consistent with early-phase sloshing induced by an off-axis minor merger. Abell 3572, an X-ray-faint gas-poor cluster located 1.6 Mpc to the south, is a promising candidate for the perturber. Given the lack of clear signatures of prominent AGN feedback in Abell 3571, these results suggest that sloshing-driven gas redistribution may contribute to delaying the re-establishment of a strong cool core in Abell 3571.

astro-ph.HE↗

arXiv2026

AGN Fueling and Radio Jet Evolution in the Galaxy Group NGC 5044 revealed by VLBA HI Absorption and Proper-Motion Radio Observations

The role of cooling gas in triggering active galactic nucleus (AGN) feedback in the centers of galaxy groups and clusters remains a key open question. NGC 5044, the X-ray brightest galaxy group, hosts the largest known reservoir of molecular gas among cool-core groups and exhibits multiple AGN outbursts, making it an ideal system to study AGN feeding. We present new multi-frequency Very Long Baseline Array (VLBA) observations of NGC 5044 at 1.4 GHz, 4.9 GHz, and 8.4 GHz, combining continuum imaging with HI spectroscopy. At 1.4 GHz, we recovered the previously known symmetric northeast-southwest jets extending for 5.5 pc each, along with evidence for previously undetected, more extended faint emission aligned with the older, kpc-scale outbursts. Comparison of 4.9 GHz and 8.4 GHz data from 2020 and 2024 reveals clear outward proper motion of jet components, yielding an average expansion speed of $(0.10\pm0.02)\,c$ and implying a dynamical age of $\sim$180 yr for the ejection of the parsec-scale jet components. The jet width profile suggests a transition from parabolic to conical collimation at a few $\times 10^{4}$ Schwarzschild radii. We detect a narrow, redshifted HI absorption line at $+264\,\mathrm{km\,s^{-1}}$ against the VLBA core, tracing a compact, cold atomic cloud within $\sim$10-20 pc of the AGN. The close velocity correspondence with previously detected CO and HI absorption features in ALMA and MeerKAT data, respectively, demonstrates that cold atomic and molecular gas coexists in infalling clouds at parsec scales. Overall, these results provide an unprecedented high angular resolution view of AGN cycling, jet growth, and feeding in a galaxy group environment.

astro-ph.GA↗

arXiv2026

Mapping dark matter in the Bullet Cluster using JWST imaging and spectroscopy

We present an updated gravitational lens model of the Bullet cluster (1E 0657-56) by combining JWST NIRCam imaging and NIRSpec spectroscopy. Although previous lens models relied on many multiply imaged galaxies, only six systems had spectroscopic redshifts prior to this work. Our lens model is constrained by a catalogue of 135 secure multiple images from 27 background galaxies with spectroscopic redshifts, uniformly covering both subclusters and a wide redshift range of 0.9 - 6.7. We also provide a catalogue of 199 multiple image candidates. We modelled the cluster with Lenstool and incorporated several large-scale haloes, cluster members, the intracluster gas, and group-scale haloes surrounding the cluster core, motivated by spectroscopic studies of cluster member kinematics. We describe the main cluster component with a complex, elongated double-peaked distribution, and the subcluster with a single large-scale halo aligning closely with the brightest cluster galaxy ($4_{-2}^{+3}$ kpc). The uncertainty of the displacement has been improved threefold thanks to the addition of JWST systems. The addition of group-scale substructures, roughly following the two axes of cluster assembly, improves the fit to the multiple image positions and provides a physically motivated alternative to constant shear. Our lens model shows the closest agreement with previous studies in aperture mass profiles at $\sim60$ kpc from the brightest cluster galaxies (BCGs), but exhibits significant differences in the detailed mass distribution as a result of different lens-modelling strategies and adopted constraints. The differences are reflected in small but spatially coherent deviations between the new spectroscopic redshifts and redshifts predicted by earlier lens models.

astro-ph.CO↗

arXiv2025

Mapping the Nearest Ancient Sloshing Cold Front in the Sky with XMM-Newton

The Virgo Cluster is the nearest cool core cluster that features two well-studied sloshing cold fronts at radii of $r \approx 30$ kpc and $r \approx 90$ kpc, respectively. In this work, we present results of XMM-Newton mosaic observations of a third, southwestern, cold front at a radius of $r \approx 250$ kpc, originally discovered with Suzaku. All three cold fronts are likely to be parts of an enormous swirling pattern, rooted in the core. The comparison with a numerical simulation of a binary cluster merger indicates that these cold fronts were produced in the same single event $-$ likely the infall of M49 from the northwest of Virgo and it is now re-entering the cluster from the south. This outermost cold front has probably survived for $2-3$ Gyr since the disturbance. We identified single sharp edges in the surface brightness profiles of the southern and southwestern sections of the cold front, whereas the western section is better characterized with double edges. This implies that magnetic fields have preserved the leading edge of the cold front, while its western side is beginning to split into two cold fronts likely due to Kelvin-Helmholtz instabilities. The slopes of the 2D power spectrum of the X-ray surface brightness fluctuations, derived for the brighter side of the cold front, are consistent with the expectation from Kolmogorov turbulence. Our findings highlight the role of cold fronts in shaping the thermal dynamics of the intracluster medium beyond the cluster core, which has important implications for cluster cosmology. Next-generation X-ray observatories, such as the proposed AXIS mission, will be ideal for identifying and characterizing ancient cold fronts.

astro-ph.HE↗

arXiv2025

SDSS-C4 3028: The Nearest Blue Galaxy Cluster Devoid of an Intracluster Medium

SDSS-C4 3028 is a galaxy cluster at $z=0.061$, notable for its unusually high fraction of star-forming galaxies with 19 star-forming and 11 quiescent spectroscopically-confirmed member galaxies. From Subaru/HSC imaging, we derived a weak lensing mass of $M_{200} = (1.3 \pm 0.9) \times 10^{14} \rm M_\odot$, indicating a low-mass cluster. This is in excellent agreement with its dynamical mass of $M_{200} = (1.0\pm0.4)\times10^{14} \rm M_\odot$, derived from SDSS spectroscopic data. XMM-Newton observations reveal that its X-ray emission is uniform and fully consistent with the astrophysical X-ray background, with no evidence for an intracluster medium (ICM). The 3$\sigma$ upper limit of $L_{\rm X}(0.1-2.4\rm keV)=7.7\times10^{42}$ erg s$^{-1}$ on the cluster's X-ray luminosity falls below the value expected from the $L_{\rm X}-M_{\rm halo}$ scaling relation of nearby galaxy clusters. We derived star-formation histories for its member galaxies using the photometric spectral energy distribution from SDSS, 2MASS, and WISE data. Most of its quiescent galaxies reside within the central 300 kpc, while star-forming ones dominate the outer region (300 kpc - 1 Mpc). The core region has formed the bulk of its stellar mass approximately 1.5 Gyr earlier than the outskirts. We infer a long quenching time of $>3$ Gyr for its quiescent galaxies, consistent with slow quenching mechanisms such as galaxy-galaxy interaction or strangulation. These findings suggest that SDSS-C4 3028 may have undergone an "inside-out" formation and quenching process. Its ICM may have been expelled by intense AGN feedback after core formation but before full cluster assembly. The high fraction ($\sim$0.63) of star-forming members likely results from the absence of ram pressure stripping in this blue cluster, supporting the important role of ram pressure stripping in quenching galaxies in clusters.

astro-ph.GA↗

arXiv2025

Star Formation under a Cosmic Microscope: Highly magnified z = 11 galaxy behind the Bullet Cluster

We present measurements of stellar population properties of a newly discovered spectroscopically confirmed $z=11.10^{+0.11}_{-0.26}$, gravitationally lensed galaxy, using JWST NIRSpec PRISM spectroscopy and NIRCam imaging. The arc is highly magnified by the Bullet Cluster (magnification factor ${\mu}=14.0^{+6.2}_{-0.3}$. It contains three star-forming components of which one is barely resolved and two are unresolved, giving intrinsic sizes of $\lesssim 10pc$. The clumps also contain ~50% of the total stellar mass. The galaxy formed the majority of its stars ~150Myr ago (by z~14). The spectrum shows a pronounced damping wing, typical for galaxies deep in the reionisation era and indicating a neutral IGM at this line of sight. The intrinsic luminosity of the galaxy is $0.086^{+0.008}_{-0.030} L^*$ (with $L^*$ being the characteristic luminosity for this redshift), making it the lowest luminosity spectroscopically confirmed galaxy at $z>10$ discovered to date.

astro-ph.GA↗

arXiv2025

Decoding AGN Feedback with X-arithmetic: From Morphology to Physical Mechanisms

Feedback from Active Galactic Nuclei (AGN) is a key process in the evolution of massive halos in the Universe. New observational information on feedback is crucial for improving the implementation of the physics in numerical models. In this work, we apply a novel image-manipulation technique, termed 'X-arithmetic', to a sample of 15 galaxy clusters and groups deeply observed with Chandra. This technique decomposes perturbations in feedback-dominated regions into images excluding either (1) weak shocks and sound waves, (2) bubbles inflated by jets, or (3) cooling and slow gas motions (isobaric perturbations), enabling efficient spatial identification of these features without involving spectroscopic analysis. We confirm the nature of previously (spectroscopically-)identified features and newly establish the origin of other structures. We find that feedback produces multiple shocks in groups and massive galaxies, but only one to two shocks in clusters. Prominent isobaric structures are abundant around inner cavities in clusters, compared to almost no such structures in groups. These differences suggest that feedback effects are stronger in smaller-mass systems, possibly due to the shallower gravitational potential of groups or more violent feedback. Follow-up spectroscopy, guided by the X-arithmetic results, suggests that earlier-identified "isothermal shocks" could be a mix of isobaric and adiabatic structures. We applied X-arithmetic to galaxy cluster simulations, demonstrating its straightforward application and future potential for testing the feedback physics details in simulations. Our feasibility study shows that imaging data from future X-ray observatories like AXIS will be ideal for expanding X-arithmetic application to a larger sample of objects.

astro-ph.GA↗

arXiv2025

Constraints on Non-Thermal Pressure at galaxy cluster outskirts from a Joint SPT and XMM-Newton Analysis

We present joint South Pole Telescope (SPT) and XMM-Newton observations of 8 massive galaxy clusters (0.8--1.7$\times$10$^{15}$ M$_{\odot}$) spanning a redshift range of 0.16 to 0.35. Employing a novel SZ+X-ray fitting technique, we effectively constrain the thermodynamic properties of these clusters out to the virial radius. The resulting best-fit electron density, deprojected temperature, and deprojected pressure profiles are in good agreement with previous observations of massive clusters. For the majority of the cluster sample (5 out of 8 clusters), the entropy profiles exhibit a self-similar behavior near the virial radius. We further derive hydrostatic mass, gas mass, and gas fraction profiles for all clusters up to the virial radius. Comparing the enclosed gas fraction profiles with the universal gas fraction profile, we obtain non-thermal pressure fraction profiles for our cluster sample at $>$$R_{500}$, demonstrating a steeper increase between $R_{500}$ and $R_{200}$ that is consistent with the hydrodynamical simulations. Our analysis yields non-thermal pressure fraction ranges of 8--28% (median: 15 $\pm$ 11%) at $R_{500}$ and 21--35% (median: 27 $\pm$ 12%) at $R_{200}$. Notably, weak-lensing mass measurements are available for only four clusters in our sample, and our recovered total cluster masses, after accounting for non-thermal pressure, are consistent with these measurements.

astro-ph.GA↗

arXiv2025

PSZ2 G181.06+48.47 III: weak-lensing analysis and merging scenario reconstruction of a low-mass cluster with exceptionally-distant radio relics

The galaxy cluster PSZ2 G181.06+48.47 ($z=0.234$) is a post-merging system that exhibits symmetric double radio relics separated by ~2.7 Mpc. We present the first weak-lensing analysis of PSZ2 G181.06+48.47 and propose possible merging scenarios using numerical simulations. Our analysis with Subaru Hyper Suprime-Cam imaging identifies a binary dark matter structure consisting of northern and southern components, separated by ~500 kpc. Assuming Navarro-Frenk-White (NFW) halos, the masses for the northern and southern subclusters are $M_{200c}^{N} = 0.88_{-0.30}^{+0.35} \times 10^{14} M_{\odot}$ and $M_{200c}^{S} = 2.71_{-0.48}^{+0.51} \times 10^{14} M_{\odot}$, respectively. By superposing the two NFW halos, we determine the total mass of the cluster to be $M_{200c} = 4.22_{-1.00}^{+1.10} \times 10^{14} M_{\odot}$ ($M_{500c} = 2.90_{-0.69}^{+0.75} \times 10^{14} M_{\odot}$). Our mass estimate suggests that the two relics are located around the cluster $R_{200c}$, where the density of the intracluster medium is very low. Our idealized simulations find that an off-axis collision of a 3:1 major merger can simultaneously reproduce the observed relic and dark matter halo separations. From these findings, we suggest that the system is observed ~0.9 Gyr after the first pericenter passage and is returning from the first apocenter.

astro-ph.CO↗

arXiv2025

PSZ2 G181.06+48.47 II: radio analysis of a low-mass cluster with exceptionally-distant radio relics

We report upgraded Giant Metrewave Radio Telescope and Karl J. Jansky Very Large Array radio observations of a low-mass merging galaxy cluster PSZ2 G181.06+48.47. This exceptional galaxy cluster hosts two megaparsec-scale diffuse sources, symmetrically located with respect to the cluster center and separated by about 2.6 Mpc in projection. We detect these low surface brightness sources in our new high-frequency observations (0.3-2 GHz) and classify them as radio relics associated with merger-driven shock fronts. The southwest relic exhibits an inverted morphology and shows evidence of spectral steepening in the post-shock region, potentially tracing a high Mach number shock ($\sim 4$) under the framework of diffusive shock acceleration. The northeast relic is found to be highly polarized with a 22% average polarization fraction at 1.5 GHz and aligned magnetic field vectors. Its spectral and polarization properties, along with the presence of a nearby tailed galaxy, support re-acceleration scenarios. The merger axis defined by the two relics is tilted by $\sim 45$ degree with respect to the plane of the sky, which implies an unprecedented physical separation of $\sim 3.5$ Mpc. We also detect a possible faint radio halo, suggesting weak turbulence in the central cluster region. We conclude that the faint double relics can be best explained by two outward moving shock waves in which particles are (re-)accelerated and that the cluster is in an evolved merger state. PSZ2 G181.06+48.47 presents a unique opportunity to investigate particle acceleration in low mass systems characterized by large relic separations.

astro-ph.CO↗

arXiv2025

PSZ2 G181.06+48.47 I: X-ray exploration of a low-mass cluster with exceptionally-distant radio relics

Relics are diffuse, highly-polarized radio sources that trace merger-driven shocks at the periphery of merging galaxy clusters. The LOFAR survey recently discovered a rare example of double relics in the low-mass cluster PSZ2 G181.06+48.47. Through a detailed exploration of new Chandra and XMM-Newton observations, we reveal that PSZ2 G181.06+48.47 has a lower mass ($M_{500,X}=2.32^{+0.29}_{-0.25}\times10^{14}$ M$_{\odot}$) than previously thought. Despite its cool global temperature of $kT_{500}=3.62^{+0.15}_{-0.07}$ keV, PSZ2 G181.06+48.47 is one of the most disturbed clusters in the Planck sample, with a complex morphological and thermodynamic structure. We discover a set of three discontinuities within <500 kpc of the cluster center, and, from a surface brightness analysis, place $5\sigma$ upper limits of $M_{NE}<1.43$ and $M_{SW}<1.57$ for any shock associated with the relic locations. We also revise established scaling relations for double radio-relics by adding 12 new systems not included in previous work. The PSZ2 G181.06+48.47 relics have the widest separation (scaled for $r_{500}$) of all known double-relic systems. The exceptional distance from the cluster center ($>r_{200}$), indicates the relics may be associated with shocks in the ``run-away" phase. We propose that this late-stage, post-apocenter merger is captured as the two subclusters with a mass ratio of 1.2-1.4 fall back into each other. The outer relic shocks were likely produced at the first core passage, while the inner discontinuities are associated with the second infall.

astro-ph.HE↗

arXiv2025

Revisiting the Group-Dominant Elliptical NGC 5044 in the Radio Band: Continuum Emission and Detection of HI Absorption

We present new MeerKAT L-band (continuum and HI) and upgraded Giant Metrewave Radio Telescope (300-850 MHz) observations of the archetypal cool-core group-dominant early-type galaxy NGC 5044. Our new continuum images reveal diffuse, steep spectrum ($\alpha_{0.99\,\rm GHz}^{1.56\,\rm GHz}=-1.53\pm0.6$) radio emission extending about 25 kpc around the unresolved radio core. The observed radio emission overlaps with the known X-ray cavities, but is not confined to them. We also find the first direct evidence of neutral atomic gas in NGC 5044, in the form of a 3.8$\sigma$ significant two-component HI absorption line seen against the emission of the active nucleus. The peak velocities are well correlated with the previously reported CO(2-1) absorption, but the HI lines are moderately broader, spanning velocities from $265\,\rm \, km\,s^{-1}$ to $305\,\rm \, km\,s^{-1}$. We do not detect HI emission, but place an upper limit of $M_{HI}< 5.4 \times 10^{7} \, M_{\odot}$ in the central 15 arcsec (2.2 kpc) of the galaxy. This is significantly less than the estimated molecular gas content, and implies a molecular-to-atomic mass ratio of $\geq $1.7:1, consistent with these gas phases forming through cooling from the hot intra-group medium. We also constrain the spin temperature to $T_{\rm spin}\leq 950\,\rm K$, indicating that the detected HI is in the cold neutral phase.

astro-ph.GA↗

arXiv2024

A Chandra Study of the NGC7618/UGC12491 Major Group Merger at Apogee: Multiple Cold Fronts, Boxy Wings, Filaments, and Arc-shaped Slingshot Tails

Analyses of major group mergers are key to understanding the evolution of large-scale structure in the Universe and the microphysical properties of the hot gas in these systems. We present imaging and spectral analyses of deep Chandra observations of hot gas structures formed in the major merger of the NGC 7618 and UGC 12491 galaxy groups and compare the observed hot gas morphology, temperatures, and abundances with recent simulations. The morphology of the observed multiple cold front edges and boxy wings are consistent with those expected to be formed by Kelvin-Helmholtz instabilities and gas sloshing in inviscid gas. The arc-shaped slingshot tail morphologies seen in each galaxy suggest that the dominant galaxies are near their orbital apogee after having experienced at least one core passage at a large impact parameter.

astro-ph.CO↗

arXiv2024

Probing the high frequency variability of NGC 5044: the key to AGN feedback

The active galactic nucleus (AGN) feeding and feedback process in the centers of galaxy clusters and groups is still not well understood. NGC 5044 is the ideal system in which to study AGN feedback. It hosts the largest known reservoir of cold gas in any cool-core galaxy group, and features several past epochs of AGN feedback imprinted as cavities in the X-ray bright intragroup medium (IGrM), as well as parsec scale jets. We present Submillimeter Array (SMA), Karl G. Jansky Very Large Array (VLA), James Clerk Maxwell Telescope (JCMT), and Atacama Large Millimeter/submillimeter Array (ALMA) high frequency observations of NGC 5044 to assess the time variability of the mmwaveband emission from the accretion disk, and quantify the Spectral Energy Distribution (SED) from the radio to sub-millimeter band. The SED is well described by advection dominated accretion flow (ADAF) model and self-absorbed jet emission from an aging plasma with tau = 1kyr. We find a characteristic variability timescale of 150 days, which constrains the ADAF emission region to about 0.1pc, and the magnetic field to 4.7mG in the jets and and 870G in the accretion disk. A longer monitoring/sampling will allow to understand if the underlying process is truly periodic in nature.

astro-ph.GA↗

arXiv2024

A Swift X-ray view of the SMS4 sample -- II: X-ray properties of 17 bright radio sources

Based on a proposal to observe 18 bright radio sources from the SMS4 catalog with the Neil Gehrels Swift Observatory (hereafter Swift), we obtained X-ray observations of 17 targets (one target was not observed). Following up our first paper that discussed 31 sources (see Maselli et al. 2022; 20 sources detected as point sources and one very extended source), we present results for this final sample of 17 radio sources, that previously lacked dedicated, pointed narrow FOV X-ray observations. One of these 17 sources, undetected by Swift due to a very short exposure, was instead detected by eROSITA, and given in the Data Release 1 (DR1) Catalog. No 1eRASS source was found in the DR1 for the remaining source, unobserved by Swift. The new Swift observations led to eleven X-ray source detections in the 0.3-10 keV band and six upper limits. We investigated the extent of the X-ray emission, the hardness ratio, and when statistics allowed we carried out a spectral analysis. The X-ray emission of eight sources is consistent with point-like emission, while three sources show clear evidence of extent, each with peculiar properties. We used the X-ray determined positions and uncertainties of the twelve detected sources to establish associations with infrared and optical sources from the AllWISE and the GSC 2.4.2 catalogs. Requiring a detection in both the infrared and the optical bands to establish a candidate counterpart for our X-ray detections, we identify counterparts for all twelve sources. We discuss the interesting structure of MRC B0344-345 and PKS B2148-555, two of the six extended X-ray sources that we detected in both our Swift campaigns, and suggest they are very promising for further X-ray and radio investigations. For the 38 SMS4 sources that lack pointed, narrow FOV X-ray telescope observations, after our Swift campaigns, we list 18 likely counterparts from the eROSITA DR1 catalog.

astro-ph.HE↗

arXiv2024

A candidate supermassive black hole in a gravitationally-lensed galaxy at $z\approx10$

While supermassive black holes (BHs) are widely observed in the nearby and distant universe, their origin remains debated with two viable formation scenarios with light and heavy seeds. In the light seeding model, the first BHs form from the collapse of massive stars with masses of $10-100 \ \rm{M_{\odot}}$, while the heavy seeding model posits the formation of $10^{4-5} \ \rm{M_{\odot}}$ seeds from direct collapse. The detection of BHs at redshifts $z\gtrsim10$, edging closer to their formation epoch, provides critical observational discrimination between these scenarios. Here, we focus on the JWST-detected galaxy, GHZ 9, at $z\approx10$ that is lensed by the foreground cluster, Abell 2744. Based on 2.1 Ms deep Chandra observations, we detect a candidate X-ray AGN, which is spatially coincident with the high-redshift galaxy, GHZ 9. The BH candidate is inferred to have a bolometric luminosity of $(1.0^{+0.5}_{-0.4})\times10^{46} \ \rm{erg \ s^{-1}}$, which corresponds to a BH mass of $(8.0^{+3.7}_{-3.2})\times10^7 \ \rm{M_{\odot}}$ assuming Eddington-limited accretion. This extreme mass at such an early cosmic epoch suggests the heavy seed origin for this BH candidate. Based on the Chandra and JWST discoveries of extremely high-redshift quasars, we have constructed the first simple AGN luminosity function extending to $z\approx10$. Comparison of this luminosity function with theoretical models indicates an over-abundant $z\approx10$ BH population, consistent with a higher-than-expected seed formation efficiency.

astro-ph.GA↗