Galaxy Evolution and AGN

arXiv:2507.02284v2 Announce Type: replace Abstract: The Milky Way Survey of the Dark Energy Spectroscopic Instrument (DESI) has so far observed three classical dwarf spheroidal galaxies (dSphs): Draco, Sextans and Ursa Minor. Based on the observed line-of-sight velocities and metallicities of their member stars, we apply the axisymmetric Jeans Anisotropic Multi-Gaussian Expansion modeling (JAM) approach to recover their inner dark matter distributions. In particular, both the traditional single-population Jeans model and the multiple population chemodynamical model are adopted. With the chemodynamical model, we divide member stars of each dSph into metal-rich and metal-poor populations. The metal-rich populations are more centrally concentrated and dynamically colder, featuring lower velocity dispersion profiles than the metal-poor populations. We find a diversity of the inner density slopes $\gamma$ of dark matter halos, with the best constraints by single-population or chemodynamical models consistent with each other. The inner density slopes are $0.71^{+0.34}_{-0.35}$, $0.26^{+0.22}_{-0.12}$ and $0.33^{+0.20}_{-0.16}$ for Draco, Sextans and Ursa Minor, respectively. We also present the measured astrophysical J and D factors of the three dSphs. Our results indicate that the study of the dark matter content of dSphs through stellar kinematics is still subject to uncertainties behind both the methodology and the observed data, through comparisons with previous measurements and data sets.

arXiv:2509.13411v1 Announce Type: new Abstract: We present results from a deep, coordinated $XMM$-$Newton$ + $NuSTAR$ observation of the type 1 Seyfert PG 1426+015, a source of particular interest as the most massive reverberation-mapped black hole to date ($\log [M_{\rm{BH}}/M_{\odot}]$ = $9.01^{+0.11}_{-0.16}$). The high-resolution RGS data confirm the 'bare' nature of the source, showing no evidence for absorption beyond the Galactic column, while the broadband spectrum unambiguously reveals the presence of relativistic reflection from the innermost accretion disc (in the form of a relativistically broadened iron emission and associated Compton reflection hump) as well as confirming the presence of the strong soft excess reported previously. We explore whether relativistic reflection can successfully account for the soft excess along with the higher-energy reflection features, utilizing the two most-commonly used reflection codes (REFLIONX, XILLVER). Ultimately we find that both models are able to successfully reproduce the soft excess, though in the case of the XILLVER model this is contingent on reducing the strength of the O VIII line included in the model, as otherwise this feature prevents the model from reproducing the data. The reflection models that successfully reproduce the broadband data imply a relatively high density for the accretion disc of $\log [n_{\rm{e}} / \rm{cm}^{-3}] \sim 18$, consistent with the loose anti-correlation seen from other AGN in the $\log [n_{\rm{e}} / \rm{cm}^{-3}]$ vs $\log[m_{\rm{BH}} \dot{m}^2]$ plane, as well as a moderate-to-high black hole spin of $a^* \gtrsim 0.7$. This preliminary spin constraint is strongly dependent on the assumption that the soft excess is dominated by relativistic reflection.

arXiv:2509.14206v1 Announce Type: new Abstract: As old stellar systems, globular clusters (GCs) are key fossil tracers of galaxy formation and interaction histories. This paper is part of the LEWIS project, an integral-field spectroscopic survey of ultra-diffuse galaxies (UDGs) in the Hydra I cluster. We use MUSE spectroscopy and new VIRCAM $H$-band imaging data to study the GC populations and dark matter content in four dwarf galaxies. We retrieved line-of-sight velocities for all sources in the observed MUSE fields. Since the spectroscopic measurements are limited to relatively bright sources, we developed a multi-band photometric procedure to identify additional GC candidates too faint for spectroscopic confirmation. GC candidates were selected using a combination of photometric properties and morphometric criteria. Additionally, the $H$-band observations were used to constrain the stellar masses of the studied galaxies. Based on the spectroscopic classification, we confirm one GC in UDG3, two in UDG7, and four in UDG11, while UDG9 has no spectroscopically confirmed bright GCs. We identify four intra-cluster GCs in the vicinity of UDG3 and UDG11, and one ultra-compact dwarf with a radial velocity only $\Delta v = -85 \pm 10\mathrm{km\ s^{-1}}$ relative to UDG7, suggesting it may be bound to it. Considering completeness corrections and accounting for possible contamination, from photometry we estimate that the number of GCs ranges between 0 and $\sim40$ for the investigated UDGs. Their specific frequencies suggest that three out of four UDGs are either GC-rich, similar to those in the Coma cluster, or belong to an intermediate population as seen in the Perseus cluster. Dark matter content estimates, inferred from GC counts and stellar mass, indicate that these galaxies are dark-matter dominated, with dynamical-to-stellar mass ratios of $M_{\mathrm{dyn}} / M_\star \sim 10-1000$.

arXiv:2509.10271v1 Announce Type: new Abstract: Galaxy evolution theories require co-evolution between accreting supermassive black holes (SMBH) and galaxies to explain many properties of the local galaxy population, yet observational evidence for the mechanisms driving this co-evolution is lacking. The recent star-formation histories of the host galaxies of accreting SMBHs (Active Galactic Nuclei, AGNs) can help constrain the processes that feed SMBHs and halt star formation in galaxies, but are difficult to obtain for the most luminous AGNs (quasars). We introduce Mean-Field Independent Component Analysis (MFICA) to decompose quasar spectra and obtain recent star formation histories of their host galaxies. Applying MFICA to quasar spectra from the Sloan Digital Sky Survey (SDSS) DR7 Quasar Catalogue in the redshift range $0.16 \leq z \leq 0.76$, we find that 53 per cent of quasar host galaxies are star-forming, 17 per cent lie in the green-valley, while only 5 per cent are quiescent. This contrasts with 14, 11, and 74 per cent of a mass-matched control sample that are star-forming, green-valley, and quiescent, respectively. We find that $\sim25$ per cent of quasars are hosted by post-starburst galaxies, an excess of $28\pm1$ compared to our control sample. While the heterogeneity of recent star formation histories implies multiple SMBH feeding mechanisms, the excess of post-starburst host galaxies demonstrates the link between accreting SMBHs and a recent starburst followed by rapid quenching. Given that massive post-starburst galaxies are predominantly caused by gas-rich major mergers, our results indicate that $30-50$ per cent of quasars originate from merger-induced starbursts.

arXiv:2508.00774v2 Announce Type: replace Abstract: We present a novel formation channel for supermassive black hole (SMBH) binaries in the early Universe, driven by primordial black holes (PBHs). Using high-resolution hydrodynamical simulations, we explore the role of massive PBHs ($m_{BH} \sim 10^6 M_\odot$) in catalyzing the formation of direct-collapse black holes (DCBHs), providing a natural in situ pathway for binary SMBH formation. PBHs enhance local overdensities, accelerate structure formation, and exert thermal feedback on the surrounding medium via accretion. Lyman-Werner (LW) radiation from accreting PBHs suppresses H$2$ cooling, shifting the dominant gas coolant to atomic hydrogen. When combined with significant baryon-dark matter streaming velocities ($v_{b\chi} \gtrsim 0.8 \sigma_{b\chi}$, where $\sigma_{b\chi}$ is the root-mean-square streaming velocity), these effects facilitate the formation of dense, gravitationally unstable, atomically cooling gas clouds in the PBH's wake. These clouds exhibit sustained high inflow rates ($\dot{M}_{infall} \gtrsim 0.01 - 0.1 M_\odot yr^{-1}$), providing ideal conditions for DCBH formation from rapidly growing supermassive stars of $\sim 10^5 M_\odot$ at redshifts $z \sim 20 - 10$. The resulting systems form SMBH binaries with initial mass ratios $q \sim O(0.1)$ and separations of $\sim 10$ pc. Such PBH-DCBH binaries provide testable predictions for JWST and ALMA, potentially explaining select high-$z$ sources such as the Little Red Dots (LRDs), and represent gravitational-wave sources for future missions like LISA and TianQin-bridging early-Universe black hole physics, multi-messenger astronomy, and dark matter theory.

arXiv:2410.21365v2 Announce Type: replace Abstract: The stellar halo of the Milky Way comprises an abundance of chemical signatures from accretion events and \textit{in-situ} evolution, that form an interweaving tapestry in kinematic space. To untangle this, we consider the mixtures of chemical information, in a given region of integral of motion space, as a variant of the blind source separation problem using non-negative matrix factorisation (NMF). Specifically, we examine the variation in [Fe/H], [Mg/Fe], and [Al/Fe] distributions of APOGEE DR17 stars across the $(E,L_z)$ plane of the halo. When 2 components are prescribed, the NMF algorithm splits stellar halo into low- and high-energy components in the $(E,L_z)$ plane which approximately correspond to the accreted and \textit{in-situ} halo respectively. We use these components to define a boundary between the \textit{in-situ} and the accreted stellar halo, and calculate their fractional contribution to the stellar halo as a function of energy, galactocentric spherical radius ($r$), height ($z$), and galactocentric cylindrical radius ($R$). Using a stellar halo defined by kinematic cuts, we derive a boundary in $(E,L_z)$ space where the halo transitions from \textit{in-situ} dominated to accretion dominated. Spatially, we find that this transition happens at $(r,z,R) \approx (8.7, 3.0, 8.1)$ kpc. We find that between 34\% to 53\% of the stellar halo's content is of accreted origin. Upon prescribing more components to the NMF model, we find evidence for overlapping chemical evolution sequences. We examine features within these components that resemble known substructures in the halo, such as \textit{Eos} and \textit{Aurora}.

arXiv:2509.05459v1 Announce Type: new Abstract: The JWST has enabled the discovery of Active Galactic Nuclei at high redshifts. The intrinsic UV spectrum of GN-z11 at redshift z = 10.6 has a spectral slope compatible with a standard accretion disc. By fitting a disc model to its spectrum, we find that the mass of the black hole must be above 1.6e7 Msun in order that it lies below the Eddington limit. We define this mass as the Eddington mass of the black hole. We note that the spectral shape is consistent with that of accreting stellar mass black holes sources in their soft state, for which no variability is expected. Mom-z14 is a more distant object at z = 14.44 and has a similar UV slope. Disc model-fitting gives a similar result but lower mass accretion rate. We also examine 3 further high redshift objects: GS z14-1, GHZ2 and GS-z11-1 at z = 13.86, 12.34 and 11.28, again obtaining similar results. If sub-Eddington accretion discs are indeed the origin of much of the UV emission from these objects, then the existence of massive black holes less than 440 and 290 Myr after the Big Bang point either to exceptional black hole seeds or to primordial black holes. The observed spread of UV spectral slopes in high redshift objects suggests that our approach may be relevant to about half of that population.

arXiv:2509.05423v1 Announce Type: new Abstract: JWST has revealed a previously unknown population of low-luminosity active galactic nuclei (AGN) in the early Universe. These JWST-AGN at high redshifts are characterised by a set of peculiar properties, including unusually weak X-ray emission. Here we investigate the apparent lack of X-ray emission in the framework of the ``AGN radiative dusty feedback'' scenario based on the effective Eddington limit for dust. We analyse how the boundary in the $N_\mathrm{H} - \lambda$ plane, defined by the column density versus the Eddington ratio, is modified as a function of the dusty gas parameters (metallicity, dust grain size and composition). Low metallicity gas with little dust content tends to survive against radiation pressure, and likely accumulates in the nuclear region. We suggest that such dust-poor gas can provide long-lived absorption and may lead to heavy X-ray obscuration, as observed in early JWST-AGN. The blowout vs. stalling condition of the obscuring clouds indicates that higher metallicities are required to eject heavier column densities, while large columns of gas can stall in low metallicity environments. Therefore the metallicity may play a key role in the AGN radiative dusty feedback scenario. We discuss how other peculiar properties of JWST-AGN --such as Balmer absorption features and weak radio emission-- may be naturally interpreted within the same physical framework.

arXiv:2509.03593v1 Announce Type: new Abstract: Transient events associated with supermassive black holes provide rare opportunities to study accretion and the environments of supermassive black holes. We present a multiwavelength study of AT2020adpi (ZTF20acvfraq), a luminous optical/UV transient in the nucleus of the galaxy WISEA J231853.77$-$103505.6 ($z=0.26$) that exhibits the properties of an ambiguous nuclear transient. Near peak, its spectral energy distribution is well described by a power law ($\lambda L_\lambda \propto \lambda^{-\alpha}$, $\alpha = 0.44 \pm 0.04$), with a maximum $g$-band luminosity of $(3.6 \pm 0.6)\times10^{44}$ erg s$^{-1}$, which is consistent with luminous AGN flares. We detect a strong mid-infrared flare ($L_\mathrm{peak}^{\mathrm{MIR}} = (2.3 \pm 0.05)\times10^{44}$ erg s$^{-1}$) delayed by $\sim$240 rest-frame days, indicating a hot dust echo from material at $\sim$0.2 pc. The optical and near-infrared spectra show broad H, He I, [OIII] lines, as well as narrow Fe II, and prominent Mg II, which is a combination not typical of TDEs. Taken together, these features suggest AT2020adpi is an ambiguous nuclear transient, where an accretion episode was triggered by stellar disruption of an accretion disk or instabilities within an active nucleus. This source demonstrates the need for careful multiwavelength analysis to distinguish between extreme AGN variability and TDEs.

arXiv:2509.03585v1 Announce Type: new Abstract: We aim to study the clustering of metal absorption lines and the structures that they arise in as a function of cosmic time. We focus on C IV and Si IV absorption features that are identified along a given quasar sightline. We exploit the two-point correlation function (2PCF) to investigate the clustering of these structures as a function of their separation. We utilise the E-XQR-30 data to perform a novel analysis at z>5. We also draw on literature surveys (including XQ-100) of lower redshift quasars to investigate the possible evolution of this clustering towards cosmic noon (i.e., z~2-3). We find no significant evolution with redshift when considering the separation of absorbers in velocity space. Since we are comparing data across a large interval of cosmic time, we also consider the separation between absorbers in the reference frame of physical distances. In this reference frame, we find that the amplitude of the clustering increases with cosmic time for both C IV and Si IV on the scales of <1500 physical kpc. For the first time, we assess the 2PCF of C IV and Si IV close to the epoch of reionisation utilising the absorber catalogue from the E-XQR-30 survey. We compare this with lower redshift data and find that, on small scales, the clustering of these structures grows with cosmic time. We compare these results to the clustering of galaxies in the GAEA simulations. It appears that the structures traced by C IV are broadly comparable to the galaxies from the considered simulations. The clustering is most similar to that of the galaxies with virial masses M~10^10.5 M_sun. We require tailor-made simulations to investigate the full range of factors contributing to the observed clustering. Future ground-based spectrographs will further facilitate surveys of absorbers at this epoch with increased sensitivity.

arXiv:2509.02842v1 Announce Type: new Abstract: [abridged] Accurately accounting for the AGN phase in galaxy evolution requires a large, clean AGN sample. This is now possible with SRG/eROSITA. The public Data Release 1 (DR1, Jan 31, 2024) includes 930,203 sources from the Western Galactic Hemisphere. The data enable the selection of a large AGN sample and the discovery of rare sources. However, scientific return depends on accurate characterisation of the X-ray emitters, requiring high-quality multiwavelength data. This paper presents the identification and classification of optical and infrared counterparts to eRASS1 sources using Gaia DR3, CatWISE2020, and Legacy Survey DR10 (LS10) with the Bayesian NWAY algorithm and trained priors. Sources were classified as Galactic or extragalactic via a Machine Learning model combining optical/IR and X-ray properties, trained on a reference sample. For extragalactic LS10 sources, photometric redshifts were computed using Circlez. Within the LS10 footprint, all 656,614 eROSITA/DR1 sources have at least one possible optical counterpart; about 570,000 are extragalactic and likely AGN. Half are new detections compared to AllWISE, Gaia, and Quaia AGN catalogues. Gaia and CatWISE2020 counterparts are less reliable, due to the surveys shallowness and the limited amount of features available to assess the probability of being an X-ray emitter. In the Galactic Plane, where the overdensity of stellar sources also increases the chance of associations, using conservative reliability cuts, we identify approximately 18,000 Gaia and 55,000 CatWISE2020 extragalactic sources. We release three high-quality counterpart catalogues, plus the training and validation sets, as a benchmark for the field. These datasets have many applications, but in particular empower researchers to build AGN samples tailored for completeness and purity, accelerating the hunt for the Universe most energetic engines.

arXiv:2503.19196v2 Announce Type: replace Abstract: The first survey data release by the Euclid mission covers approximately $63\,\mathrm{deg^2}$ in the Euclid Deep Fields to the same depth as the Euclid Wide Survey. This paper showcases, for the first time, the performance of cluster finders on Euclid data and presents examples of validated clusters in the Quick Release 1 (Q1) imaging data. We identify clusters using two algorithms (AMICO and PZWav) implemented in the Euclid cluster-detection pipeline. We explore the internal consistency of detections from the two codes, and cross-match detections with known clusters from other surveys using external multi-wavelength and spectroscopic data sets. This enables assessment of the Euclid photometric redshift accuracy and also of systematics such as mis-centring between the optical cluster centre and centres based on X-ray and/or Sunyaev--Zeldovich observations. We report 426 joint PZWav and AMICO-detected clusters with high signal-to-noise ratios over the full Q1 area in the redshift range $0.2 \leq z \leq 1.5$. The chosen redshift and signal-to-noise thresholds are motivated by the photometric quality of the early Euclid data. We provide richness estimates for each of the Euclid-detected clusters and show its correlation with various external cluster mass proxies. Out of the full sample, 77 systems are potentially new to the literature. Overall, the Q1 cluster catalogue demonstrates a successful validation of the workflow ahead of the Euclid Data Release 1, based on the consistency of internal and external properties of Euclid-detected clusters.

arXiv:2509.01017v1 Announce Type: new Abstract: We present the stellar dynamical mass of the central black hole in the nearby Seyfert galaxy MCG$-$06-30-15 using the Schwarzschild orbit-superposition method implemented in the open-source code FORSTAND. We obtained spatially resolved $K$-band nuclear stellar spectra for this galaxy with SINFONI on the VLT. We extracted the bulk stellar kinematics using Gauss$-$Hermite (GH) parameterization of the line-of-sight velocity distributions. A multicomponent surface brightness profile of the galaxy was determined from an $HST$ medium-band $V$ image. Our best-fit models indicate a black hole mass of $M_{BH}=(4.4\pm1.4) \times 10^7 M_{\odot}$ and a stellar mass-to-light ratio of $M/L$=($3.0\pm0.3$) $M_{\odot}$/$L_{\odot}$, within 1$\sigma$ confidence intervals. Our constraint on $M_{BH}$ agrees with an upper limit on the mass from stellar dynamics based on the Jeans Anisotropic Method, but is $\sim$10 times larger than the reported mass from reverberation mapping. However, our best-fit $M_{BH}$ may be systematically biased high due to the counter-rotating disk in the nucleus of MCG$-$06-30-15 and the inability of the GH parameterization to fully describe such a complicated set of stellar kinematics. In addition, a dynamical $M_{BH}$ value depends heavily on the assumed source distance, which is not yet accurately constrained for this galaxy. MCG$-$06-30-15 is only the fourth galaxy in which we can compare $M_{BH}$ from stellar dynamical modeling with that from reverberation mapping. A direct comparison of $M_{BH}$ allows us to identify and investigate the possible sources of bias associated with different mass measurement techniques, which may influence our understanding of black hole and galaxy coevolution across cosmological timescales.

arXiv:2509.02546v1 Announce Type: new Abstract: We combine new spectroscopic observations of the ultra faint dwarf galaxy (UFD) Bo\"otes I (Boo I) from the Southern Stellar Stream Spectroscopic Survey ($S^{5}$) with $\sim$15 years of archival spectroscopic data to create the largest sample of stellar kinematics and metallicities to date in any Milky Way UFD. Our combined sample includes 148 members extending out to $\sim$7 half-light radii ($r_h$), including 24 newly confirmed members, 18 binary candidates, 15 RR Lyrae stars, and 92 [Fe/H] measurements. Using this larger and more spatially extended sample, we provide updated constraints on Boo I's systemic properties, including its radial population gradients. Properly accounting for perspective rotation effects in a UFD for the first time, we detect a $4\sigma$ line-of-sight velocity gradient of $1.2\pm0.3$ km s$^{-1}$ $r_h^{-1}$ aligned along Boo I's orbit and discuss its potential tidal origins. We also infer a metallicity gradient of $-0.10\pm0.02$ dex $r_h^{-1}$ in agreement with previous studies. Using an axisymmetric Jeans model, we provide updated constraints on Boo I's dark matter density profile, which weakly favor a cusped ($\gamma=1.0^{+0.5}_{-0.6}$) dark matter profile. Lastly, we re-analyze Boo I's metallicity distribution function with a one-zone galactic chemical evolution model and place new constraints on its rapid, inefficient star formation and strong galactic outflows.

arXiv:2509.00146v1 Announce Type: new Abstract: Post-starburst galaxies (PSBs) are a population of rapidly quenched galaxies that have experienced a recent starburst. Several aspects of the origin and nature of PSBs are currently debated. For example, some PSBs unexpectedly host substantial molecular gas despite their low star-formation activity. Furthermore, the relative role of galaxy mergers, interaction, and stellar or black hole feedback in the formation of PSBs remains unclear. We investigate the nature of PSBs at z=0.7 and z=1 selected via rest-frame optical photometric properties, using the FIREbox cosmological simulation. The fraction of PSBs in FIREbox is in reasonable agreement with observational estimates. However, only ~10% of PSBs in FIREbox are `true' PSBs with temporarily quenched star-formation activity. Most galaxies selected as PSBs in FIREbox are impostors, having star-formation rates and gas masses that are comparable to those of non-PSB galaxies with similar stellar masses. Furthermore, PSBs rich in molecular gas are almost exclusively impostors. `True' PSBs and impostors differ on average in their mid-to-near infrared ratio but with significant scatter. By combining the impostor frequency among star forming galaxies in FIREbox with observational estimates, we predict that more than 70% of `true' PSBs in the Universe should originate from massive black hole feedback.

arXiv:2508.10100v2 Announce Type: replace Abstract: As ancient star clusters, globular clusters (GCs) are regarded as powerful tracers of galaxy evolution and assembly. Due to their brightness and compact sizes, GCs are employed to probe the kinematics and stellar population properties of galaxies, from the central regions out into the halo where the underlying stellar light becomes too faint for spectroscopic studies. In this work, we present a comprehensive study of the GC system of M 104 (NGC 4594, also known as the Sombrero galaxy) based on literature spectroscopic catalogues and newly collected data from Very Large Telescope (VLT) MUSE integral-field spectroscopy combined with multi-object spectroscopy from VLT FLAMES and OSIRIS at the Gran Telescopio de Canarias (GTC). We present a new catalogue of 499 GCs with radial velocity measurements that span from the inner disc region out to $\sim$ 70 kpc (24$^{\prime}$). In addition to velocities, we measure metallicities from the MUSE, OSIRIS, and FLAMES spectra of 190 GCs. Together with literature values, we collected a sample of 278 metallicities. Comparing GCs observed with multiple instruments, we find a good agreement of velocity and metallicity measurements. Studying GC kinematics with a simple model confirms a decreasing velocity dispersion profile and low rotation velocities. The blue GCs appear to be more dispersion-dominated, while the red GCs follow the kinematics of the stars more closely. We find a large scatter of GC metallicities with distance from the centre and metal-rich GCs are found over all radii. We discuss that the GC metallicity distribution with a broad metal-poor component likely reflects the complex assembly history of M 104.

arXiv:2508.09070v2 Announce Type: replace Abstract: We present a measurement of the non-Gaussian four-point correlation function (4PCF) from the DESI DR1 Luminous Red Galaxy (LRG) sample. For the gravitationally induced parity-even 4PCF, we detect a signal with a significance of 14.7$\sigma$ using our fiducial setup. We assess the robustness of this detection through a series of validation tests, including auto- and cross-correlation analyses, sky partitioning across multiple patch combinations, and variations in radial scale cuts. Due to the low completeness of the sample, we find that differences in fiber assignment implementation schemes can significantly impact estimation of the covariance and introduce biases in the data vector. After correcting for these effects, all tests yield consistent results. This is one of the first measurements of the connected 4PCF on the DESI LRG sample: the good agreement between the simulation and the data implies that the amplitude of the density fluctuation inferred from the connected 4PCF is consistent with the Planck $\Lambda$CDM cosmology. The methodology and diagnostic framework established in this work provide a foundation for interpreting parity-odd 4PCF.

arXiv:2409.15453v2 Announce Type: replace Abstract: The relative contribution of emission from stellar sources and accretion onto supermassive black holes to reionization has been brought into focus again by the apparent high abundance of faint Active Galactic Nuclei (AGN) at $4\lesssim z\lesssim11$ uncovered by JWST. We investigate here the contribution of these faint AGN to hydrogen and the early stages of helium reionization using the GPU-based radiative transfer code ATON-HE by post-processing a cosmological hydrodynamical simulation from the sherwood-relics suite of simulations. We study four models: two galaxy-only late-end reionization models, a QSO-assisted and a QSO-only model. In the QSO-assisted model, 1% of the haloes host AGN, with AGN luminosities scaled to contribute 17% of the total hydrogen-ionizing emissivity. In the QSO-only model, quasars account for all the hydrogen-ionizing emissivity, with 10% of the haloes hosting AGN. The SED of AGN is assumed to be a power-law with $\alpha=-1.7$ each with a 10 Myr lifetime. All models are calibrated to the observed mean Lyman-$\alpha$ forest transmission at $5\lesssim z\lesssim6.2$. The QSO-assisted model requires an emissivity similar to the galaxy-only models and fits the observed distribution of the Lyman-$\alpha$ optical depths well. The QSO-only model is inconsistent with the observed Lyman-$\alpha$ optical depths distribution, and produces excessively high IGM temperatures at $z\lesssim 5$ due to an early onset of HeII reionization, unless the escape fraction of HeII-ionizing photons is assumed to be low. Our results suggest that a modest AGN contribution to reionization aligns with the Lyman-$\alpha$ forest data, whereas an AGN dominated scenario is difficult to reconcile.

arXiv:2508.10100v1 Announce Type: new Abstract: As ancient star clusters, globular clusters (GCs) are regarded as powerful tracers of galaxy evolution and assembly. Due to their brightness and compact sizes, GCs are employed to probe the kinematics and stellar population properties of galaxies, from the central regions out into the halo where the underlying stellar light becomes too faint for spectroscopic studies. In this work, we present a comprehensive study of the GC system of M 104 (NGC 4594, also known as the Sombrero galaxy) based on literature spectroscopic catalogues and newly collected data from Very Large Telescope (VLT) MUSE integral-field spectroscopy combined with multi-object spectroscopy from VLT FLAMES and OSIRIS at the Gran Telescopio de Canarias (GTC). We present a new catalogue of 499 GCs with radial velocity measurements that span from the inner disc region out to $\sim$ 70 kpc (24$^{\prime}$). In addition to velocities, we measure metallicities from the MUSE, OSIRIS, and FLAMES spectra of 190 GCs. Together with literature values, we collected a sample of 278 metallicities. Comparing GCs observed with multiple instruments, we find a good agreement of velocity and metallicity measurements. Studying GC kinematics with a simple model confirms a decreasing velocity dispersion profile and low rotation velocities. The blue GCs appear to be more dispersion-dominated, while the red GCs follow the kinematics of the stars more closely. We find a large scatter of GC metallicities with distance from the centre and metal-rich GCs are found over all radii. We discuss that the GC metallicity distribution with a broad metal-poor component likely reflects the complex assembly history of M 104.

arXiv:2508.10099v1 Announce Type: new Abstract: We present detections of auroral emission lines of [OIII], [OII], [SIII], and [SII] in deep JWST/NIRSpec spectroscopy for 41 star-forming galaxies at $z=1.4-7.2$ from the AURORA survey. We combine these new observations with 98 star-forming galaxies at $z=1.3-10.6$ with detected auroral lines drawn from the literature to form a sample of 139 high-redshift galaxies with robust electron temperature and direct-method oxygen abundance determinations. This sample notably covers a wider dynamic range in metallicity than previous work, spanning $0.02-0.9$~Z$_\odot$. We calibrate empirical relations between 19 emission-line ratios and oxygen abundance, providing a robust tool set to infer accurate gas-phase metallicities of high-redshift galaxies when auroral lines are not detected. While calibrations based on lines of $\alpha$ elements (O, Ne, S, Ar) appear reliable, we find significant scatter in calibrations involving lines of N driven by a high dispersion in N/O at fixed O/H, suggesting that N-based line ratios are less reliable tracers of the oxygen abundance at high redshift. These new high-redshift calibrations are notably offset from those based on typical $z\sim0$ galaxy and HII region samples, and are better matched by samples of extreme local galaxies that are analogs of high-redshift sources. The new metallicity calibrations presented in this work pave the way for robust studies of galaxy chemical evolution in the early Universe, leading to a better understanding of baryon cycling and galaxy formation from Cosmic Noon through the Epoch of Reionization.