Search

We use spectroscopic data for |${\sim }6000$| red giant branch stars in the Small Magellanic Cloud (SMC), together with proper motion data from Gaia Early Data Release 3, to build a mass model of the SMC. We test our Jeans mass modelling method (binulator  + gravsphere) on mock data for an SMC-like dwarf undergoing severe tidal disruption, showing that we are able to successfully remove tidally unbound interlopers, recovering the dark matter density and stellar velocity anisotropy profiles within our 95 per cent confidence intervals. We then apply our method to real SMC data, finding that the stars of the cleaned sample are isotropic at all radii (at 95 per cent confidence) and that the inner dark matter density profile is dense, |$\rho _{\rm DM}(150\ {\rm pc}) = 1.58_{-0.58}^{+0.80}\times 10^8 \ {\rm M}_{\odot }\, \rm kpc^{-3}$|⁠ , consistent with a |$\Lambda$| cold dark matter cusp. Our model gives a new estimate of the SMC's total mass within 3 kpc |$(M_{\rm tot} \le 3\ {\rm kpc})$| of |$2.29\pm 0.46 \times 10^9 \ {\rm M}_{\odot }$|⁠. We also derive an astrophysical ' J -factor' of |$18.99\pm 0.16$|  GeV |$^2$|  cm |$^{-5}$| and a ' D -factor' of |$18.73\pm 0.04$|  GeV |$^2$|  cm |$^{-5}$|⁠ , making the SMC a promising target for dark matter annihilation and decay searches. Finally, we combine our findings with literature measurements to test models in which dark matter is 'heated up' by baryonic effects. We find good qualitative agreement with the Di Cintio et al. model but we deviate from the Lazar et al. model at high |$M_*/M_{200} > 10^{-2}$|⁠. We provide a new, analytical, density profile that reproduces dark matter heating behaviour over the range |$10^{-4} < M_*/M_{200} < 10^{-1}$|⁠. [ABSTRACT FROM AUTHOR]

Very compact (⁠|$R_\mathrm{e}\lesssim 1$| kpc) massive quiescent galaxies (red nuggets) are more abundant in the high-redshift Universe (⁠|$z\sim 2$| –3) than today. Their size evolution can be explained by collisionless dynamical processes in galaxy mergers which, however, fail to reproduce the diffuse low-density central cores in the local massive early-type galaxies (ETGs). We use sequences of major and minor merger N -body simulations starting with compact spherical and disc-like progenitor models to investigate the impact of supermassive black holes (SMBHs) on the evolution of the galaxies. With the ketju code we accurately follow the collisional interaction of the SMBHs with the nearby stellar population and the collisionless evolution of the galaxies and their dark matter haloes. We show that only models including SMBHs can simultaneously explain the formation of low-density cores up to sizes of |$R_\mathrm{b} \sim 1.3$| kpc with mass deficits in the observed range and the rapid half-mass size evolution. In addition, the orbital structure in the core region (tangentially biased orbits) is consistent with observation-based results for local cored ETGs. The displacement of stars by the SMBHs boost the half-mass size evolution by up to a factor of 2 and even fast rotating progenitors (compact quiescent discs) lose their rotational support after 6–8 mergers. We conclude that the presence of SMBHs is required for merger-driven evolution models of high-redshift red nuggets into local ETGs. [ABSTRACT FROM AUTHOR]

High-redshift protoclusters consisting of dusty starbursts are thought to play an important role in galaxy evolution. Their dusty nature makes them bright in the far-infrared (FIR)/submm but difficult to find in optical/near-infrared (NIR) surveys. Radio observations are an excellent way to study these dusty starbursts, as dust is transparent in the radio and there is a tight correlation between the FIR and radio emission of a galaxy. Here, we present MeerKAT 1.28 GHz radio imaging of three Herschel candidate protoclusters, with a synthesized beam size of |$\sim 7.5\, \mathrm{ arcsec}\times 6.6$|  arcsec and a central thermal noise down to |$4.35~\mu$| Jy beam−1. Our source counts are consistent with other radio counts with no evidence of overdensities. Around 95 per cent of the Herschel sources have 1.28 GHz IDs. Using the Herschel |$250~\mu$| m primary beam size as the searching radius, we find 54.2 per cent Herschel sources have multiple 1.28 GHz IDs. Our average FIR-radio correlation coefficient |$q_{250\mu \text{m}}$| is |$2.33\pm 0.26$|⁠. Adding |$q_{250\mu \text{m}}$| as a new constraint, the probability of finding chance-aligned sources is reduced by a factor of |$\sim 6$|⁠ , but with the risk of discarding true identifications of radio-loud/quiet sources. With accurate MeerKAT positions, we cross-match our Herschel sources to optical/NIR data followed by photometric redshift estimations. By removing |$z< 1$| sources, the density contrasts of two of the candidate protoclusters increase, suggestive of them being real protoclusters at |$z> 1$|⁠. There is also potentially a |$0.9< z< 1.2$| overdensity associated with one candidate protocluster. In summary, photometric redshifts from radio-optical cross-identifications have provided some tentative evidence of overdensities aligning with two of the candidate protoclusters. [ABSTRACT FROM AUTHOR]

To investigate how the radio-identified active galactic nuclei (AGN) fraction varies with cluster-centric radius, we present the projected and de-projected distributions of a large sample of Low-Frequency Array-identified radio AGN out to |$30R_{500}$| around galaxy clusters. The AGN fraction experiences a |${\sim} 25~{{\ \rm per\ cent}}$| increase above the field fraction in the cluster outskirts at around |$10R_{500}$|⁠ , a |${\sim} 20~{{\ \rm per\ cent}}$| decrease around |${\sim} 0.5R_{500}$|⁠ , and an increase of over three times the field fraction value in the very cluster core. We label these three radial windows the outer, intermediate , and inner regions respectively, and investigate how these radial trends might arise due to intrinsic properties of the AGN population. The only difference seen in host galaxy stellar mass is in the inner region, where there is a much higher fraction of massive host galaxies. Analysing AGN radio luminosity, regions with a higher AGN fraction tend to have more radio luminous AGN, and vice versa. We discuss the physical mechanisms that might be responsible for these results with reference to the literature. [ABSTRACT FROM AUTHOR]

The influence of Active Galactic Nuclei (AGN) on star formation within their host galaxies remains a topic of intense debate. One of the primary challenges in quantifying the star formation rate (SFR) within AGN hosts arises from the prevalent assumption in most methodologies, which attribute gas excitation to young stars alone. However, this assumption does not consider the contribution of the AGN to the ionization of the gas in their environment. To address this issue, we evaluate the use of strong optical emission lines to obtain the SFR surface density (⁠|$\Sigma {{\rm SFR_{AGN}}}$|⁠) in regions predominantly ionized by an AGN, using a sample of 293 AGN hosts from the MaNGA survey, with SFR measurements available through stellar population fitting. We propose calibrations involving the H |$\alpha$| and [O  iii ] |$\lambda$| 5007 emission lines, which can be used to determine |$\Sigma {{\rm SFR_{AGN}}}$|⁠ , resulting in values consistent with those estimated through stellar population fitting. [ABSTRACT FROM AUTHOR]

We report the chemical abundance pattern of GS_3073, a galaxy hosting an overmassive active black hole at |$z=5.55$|⁠ , by leveraging observations from JWST/NIRSpec and Very Large Telescope/VIsible Multi-Object Spectrograph. Based on the rest-frame ultraviolet (UV) emission lines, which trace high-density (⁠|$\sim 10^5~{\rm cm^{-3}}$|⁠) and highly ionized gas, we derive |$\rm \log (N/O) = 0.42^{+0.13}_{-0.10}$|⁠. At an estimated metallicity of |$0.2~Z_{\odot }$|⁠ , this is the most extreme nitrogen-rich object found by JWST thus far. In comparison, the relative carbon abundance derived is |$\rm \log (C/O) = -0.38^{+0.13}_{-0.11}$|⁠ , which is not significantly higher than those in local galaxies and stars with similar metallicities. We also found potential detection of [Fe  vii ] |$\lambda 6087$| and [Fe  xiv ] |$\lambda 5303$|⁠ , both blended with [Ca  v ]. We inferred a range of Fe abundances compatible with those in local stars and galaxies. Overall, the chemical abundance pattern of GS_3073 is compatible with enrichment by supermassive stars with |$M_* \gtrsim 1000~M_\odot$|⁠ , asymptotic giant branch stars, or Wolf–Rayet stars. Interestingly, when using optical emission lines that trace lower density (⁠|$\sim 10^3~{\rm cm}^{-3}$|⁠) and lower ionization gas, we found a sub-solar N/O ratio, consistent with local galaxies at the same metallicity. We interpret the difference in N/O derived from UV lines and optical lines as evidence for a stratified system, where the inner and denser region is both more chemically enriched and more ionized. Our results suggest that nitrogen loudness in high- z galaxies might be confined to the central, dense, and highly ionized regions of the galaxies, while the bulk of the galaxies evolves more normally. [ABSTRACT FROM AUTHOR]

Motivated by the need for realistic, dynamically self-consistent, evolving galaxy models that avoid the complexity of full, and zoom-in, cosmological simulations, we have developed Nexus , an integral framework to create and evolve synthetic galaxies made of collisionless and gaseous components. Nexus leverages the power of publicly available, tried-and-tested packages: the stellar-dynamics, action-based library Action-based Galaxy Modelling Architecture (AGAMA); and the adaptive mesh refinement, N -body/hydrodynamical code Ramses , modified to meet our needs. In addition, we make use of a proprietary module to account for galaxy formation physics, including gas cooling and heating, star formation, stellar feedback, and chemical enrichment. Nexus ' basic functionality consists in the generation of bespoke initial conditions (ICs) for a diversity of galaxy models, which are advanced in time to simulate the galaxy's evolution. The fully self-consistent ICs are generated with a distribution-function-based approach, as implemented in the galaxy modelling module of AGAMA – up to now restricted to collisionless components, extended in this work to treat two types of gaseous configurations: hot haloes and gas discs. Nexus allows constructing equilibrium models with disc gas fractions |$0~\le ~f_{\rm {\rm gas}}~\le ~1$|⁠ , appropriate to model both low- and high-redshift galaxies. Similarly, the framework is ideally suited to the study of galactic ecology , i.e. the dynamical interplay between stars and gas over billions of years. As a validation and illustration of our framework, we reproduce several isolated galaxy model setups reported in earlier studies, and present a new, 'nested bar' galaxy simulation. Future upgrades of Nexus will include magnetohydrodynamics and highly energetic particle ('cosmic ray') heating. [ABSTRACT FROM AUTHOR]

Accurate astrometric and photometric measurements from Gaia have led to the construction of 3D dust extinction maps which can now be used for estimating the integrated extinctions of Galactic sources located within 5 kpc. These maps based on optical observations may not be reliable for use in the ultraviolet (UV) which is more sensitive to reddening. Past studies have focussed on studying UV extinction using main-sequence stars but lack comparison with 3D dust maps. White dwarfs with well-modelled hydrogen-dominated (DA) atmospheres provide an advantage over main-sequence stars affected by magnetic activity. In this work, we study the variation of UV extinction with 3D dust maps utilizing Hubble Space Telescope (HST) and Galaxy Evolution Explorer (GALEX) observations of DA white dwarfs located within 300 pc. We used HST COS spectroscopic data of 76 sightlines to calculate the optical extinction from Si  ii column densities and validate our results with the kinematic model predictions of the local interstellar medium. Also, we combined GALEX and Gaia photometric observations of 1158 DA white dwarfs to study UV reddening by comparing observed and modelled colour–colour relations. We calculated GALEX non-linearity corrections and derived reddening coefficients [ |$R(NUV-G)=6.52\pm 1.53$| and |$R(FUV-G)=6.04\pm 2.41$| ] considering their variations with optical extinction (⁠|$\rm{A_{V}}\lt 0.1$|  mag), and found them to be in good agreement with known extinction laws. HST analysis suggests a positive bias of 0.01–0.02 mag in the optical extinction from 3D maps depending on the Galactic latitude. These results independently confirm the validity of 3D dust maps to de-redden the optical and UV observations of white dwarfs. [ABSTRACT FROM AUTHOR]

Stars move away from their birthplaces over time via a process known as radial migration, which blurs chemo–kinematic relations used for reconstructing the Milky Way (MW) formation history. To understand the true time evolution of the MW, one needs to take into account the effects of this process. We show that stellar birth radii can be derived directly from the data with minimum prior assumptions on the Galactic enrichment history. This is done by first recovering the time evolution of the stellar birth metallicity gradient, |$\mathrm{ d}\mathrm{[Fe/H]}(R, \tau)/\mathrm{ d}R$|⁠ , through its inverse relation to the metallicity range as a function of age today, allowing us to place any star with age and metallicity measurements back to its birthplace, R |$_b$|⁠. Applying our method to a large high-precision data set of MW disc subgiant stars, we find a steepening of the birth metallicity gradient from 11 to 8 Gyr ago, which coincides with the time of the last massive merger, Gaia–Sausage–Enceladus (GSE). This transition appears to play a major role in shaping both the age–metallicity relation and the bimodality in the [ |$\alpha$| /Fe]–[Fe/H] plane. By dissecting the disc into mono-R |$_b$| populations, clumps in the low-[ |$\alpha$| /Fe] sequence appear, which are not seen in the total sample and coincide in time with known star-formation bursts, possibly associated with the Sagittarius Dwarf Galaxy. We estimated that the Sun was born at |$4.5\pm 0.4$| kpc from the Galactic centre. Our R |$_b$| estimates provide the missing piece needed to recover the Milky Way formation history. [ABSTRACT FROM AUTHOR]

In a recent series of papers, supermassive black holes were used to discern pathways in galaxy evolution. By considering the black holes' coupling with their host galaxy's bulge/spheroid, the progression of mass within each component has shed light on the chronological sequence of galaxy speciation. Offsets between the galaxy-morphology-dependent |$M_{\rm bh}$| – |$M_{\rm \star ,sph}$| scaling relations trace a pattern of 'punctuated equilibrium' arising from merger-driven transitions between galaxy types, such as from spirals to dust-rich lenticulars and further to 'ellicular' and elliptical galaxies. This study delves deeper into the distinction between the ellicular galaxies – characterised by their intermediate-scale discs – and elliptical galaxies. Along the way, it is shown how some antitruncated large-scale discs in lenticular galaxies can arise from the coexistence of a steep intermediate-scale disc and a relatively shallow large-scale disc. This observation undermines application of the popular exponential-disc plus Sérsic-bulge model for lenticular galaxies and suggests some past bulge mass measurements have been overestimated. Furthermore, it is discussed how merger-driven disc-heating and blending likely leads to the spheroidalisation of discs and the conglomeration of multiple discs leads to the (high- n) Sérsicification of light profiles. The ellicular and elliptical galaxy distribution in the |$M_{\rm bh}$| – |$M_{\rm \star ,sph}$| diagram is explored relative to major-merger-built lenticular galaxies and brightest cluster galaxies. The super-quadratic |$M_{\rm bh}$| – |$M_{\rm \star }$| relations, presented herein, for merger-built systems should aid studies of massive black hole collisions and the gravitational wave background. Finally, connections to dwarf compact elliptical and ultracompact dwarf galaxies, with their 100–1000 times higher |$M_{\rm bh}/M_{\rm \star ,sph}$| ratios, are presented. [ABSTRACT FROM AUTHOR]

Dual active galactic nuclei (AGNs) offer a unique opportunity to probe the relationship between supermassive black holes (SMBH) and their host galaxies as well as the role of major mergers in triggering AGN activity. The confirmed dual AGN Mrk 266 has been studied extensively with multiwavelength imaging. Now, high-spatial-resolution IFU spectroscopy of Mrk 266 provides an opportunity to probe the kinematics of both the merger event and AGN feedback. We present for the first time high-spatial-resolution kinematic maps for both nuclei of Mrk 266 obtained with the Keck OSIRIS IFU spectrograph, utilizing adaptive optics to achieve a resolution of |$0.31$| and |$0.20\,\mathrm{ arcsec}$| for the NE and SW nuclei, respectively. Using the |$M_\text{BH} \!-\! \sigma _*$| relation for mergers, we infer an SMBH mass of approximately |$7 \times 10^{7}\, \mathrm{M}_{\odot }$| for the south-western nucleus. Additionally, we report that the molecular gas kinematics of the south-western nucleus are dominated by rotation rather than large-scale chaotic motions. The south-west nucleus also contains both a circumnuclear ring of star formation from which an inflow of molecular gas is likely fuelling the AGN and a compact, AGN-dominated outflow of highly ionized gas with a time-scale of approximately 2 Myr, significantly shorter than the time-scale of the merger. The north-eastern nucleus, on the other hand, exhibits complex kinematics related to the merger, including molecular gas that appears to have decoupled from the rotation of the stars. Our results suggest that while the AGN activity in Mrk 266 was likely triggered during the merger, AGN feeding is currently the result of processes internal to each host galaxy, thus resulting in a strong asymmetry between the two nuclei. [ABSTRACT FROM AUTHOR]

We present the spatially resolved relationship between the dust-to-gas mass ratio (DGR) and gas-phase metallicity (⁠|$Z_{\rm gas}$| or 12 + log(O/H)) (i.e. DGR– |$Z_{\rm gas}$| relation) of 11 nearby galaxies with a large-metallicity range (1.5 dex of 12 + log(O/H)) at (sub-)kpc scales. We used the large field-of-view (⁠|$\gtrsim$| 3 arcmin) optical pseudo-Integral Field Spectroscopy data taken by the TYPHOON/Progressive Integral Step Method survey, covering the optical size of galaxies, combining them with multiwavelength data [far-ultrviolet (UV) to far-infrared (IR), CO, and H  i 21 cm radio]. A large scatter of DGR in the intermediate-metallicity galaxies (8.0 |$\lt $| 12 + log(O/H) |$\lt $| 8.3) is found, which is in line with dust evolution models, where grain growth begins to dominate the mechanism of dust mass accumulation. In the lowest metallicity galaxy of our sample, Sextans A (12 + log(O/H) |$\lt $| 7.6), the star-forming regions have significantly higher DGR values (by 0.5–2 dex) than the global estimates from literature at the same metallicity, but aligns with the DGR values from metal depletion method from damped Lyman alpha systems and high hydrogen gas density regions of Sextans A. Using dust evolution models with a Bayesian Monte Carlo Markov Chain approach suggests: (1) a high supernova dust yield and (2) a negligible amount of photofragmentation by UV radiation, although we note that our sample in the low-metallicity regime is limited to Sextans A. On the other hand, it is also possible that while metallicity influences DGR, gas density also plays a role, indicating an early onset of dust grain growth in the dust mass build-up process despite its low metallicity. [ABSTRACT FROM AUTHOR]

The UV upturn refers to the increase in UV flux at wavelengths shorter than 3000  |$\mathring{\rm A}$| observed in quiescent early-type galaxies (ETGs), which still remains a puzzle. In this study, we aim to identify ETGs showing the UV upturn phenomenon within the Virgo galaxy cluster. We utilized a colour–colour diagram to identify all potential possible UV upturn galaxies. The spectral energy distributions (SED) of these galaxies were then analysed using the cigale software; we confirmed the presence of UV upturn in galaxies within the Virgo cluster. We found that the SED fitting method is the best tool to visualize and confirm the UV upturn phenomenon in ETGs. Our findings reveal that the population distributions regarding stellar mass and star formation rate properties are similar between UV upturn and red sequence galaxies. We suggest that the UV contribution originates from old stellar populations and can be modelled effectively without a burst model. Moreover, by estimating the temperature of the stellar population responsible for the UV emission, we determined it to be 13 000 K to 18 000 K. These temperature estimates support the notion that the UV upturn likely arises from the contribution of low mass evolved stellar populations (extreme horizontal branch stars). Furthermore, the Mg2 index, a metallicity indicator, in the confirmed upturn galaxies shows higher strength and follows a similar trend to previous studies. This study sheds light on the nature of UV upturn galaxies within the Virgo cluster and provides evidence that low-mass evolved stellar populations are the possible mechanisms driving the UV upturn phenomenon. [ABSTRACT FROM AUTHOR]

The JWST is allowing new measurements of gas-phase metallicities in galaxies between cosmic noon and cosmic dawn. The most robust approach uses luminosity ratios between the excited auroral transition, [O  iii ] 4364 Å, and the lower [O  iii ] 5008 Å/4960 Å lines to determine the gas temperature. The ratio of the luminosities in the latter transitions to those in hydrogen Balmer series lines then yield relatively clean metallicity estimates. In the absence of detection of the [O  iii ] auroral line, the ratios of various [O  iii ], [O  ii ], [N  ii ], and Balmer lines are used to determine metallicities. Here, we present a refined approach for extracting metallicities from these 'strong line diagnostics'. Our method exploits empirical correlations between the temperature of O  iii /O  ii regions and gas-phase metallicity. We then show, from first principles, how to extract metallicities and break degeneracies in these estimates using traditional strong line diagnostics, R 2, R 3, R 23, and O3O2 and N2O2. We show that these ratios depend also on volume correction factors, that is, on accounting for the fraction of the volume of H  ii regions that are in O  iii and O  ii , but that these can be determined self-consistently along with the metallicities. We quantify the success of our method using metallicities derived from galaxies with auroral line determinations and show that it generally works better than previous empirical approaches. The scatter in the observed line ratios and redshift evolution are largely explained by O3O2 variations. We provide publicly available routines for extracting metallicities from strong line diagnostics using our methodology. [ABSTRACT FROM AUTHOR]

Until now, observations have caught up only a handful of galaxies in ongoing buckling action. Interestingly, N -body simulations over the past several decades show that almost every bar buckles or vertically thickens as soon as it reaches its peak strength during its evolution and leads to box/peanut/x (BPX) shapes. In order to understand the effect of multiple buckling events on the observable properties of galactic bar and disc, we perform an N -body simulation of a Milky Way-type disc. The axisymmetric galaxy disc forms a bar within a Gyr of its evolution and the bar undergoes two successive buckling events. We report that the time-spans of these two buckling events are 220 Myr and 1 Gyr, which have almost similar strengths of the bending modes. As a result of these two buckling events, the full lengths of BPX shapes are around 5.8 and 8.6 kpc, which are around two-thirds of the full bar length at the end of each buckling event. We find that the first buckling occurs at a smaller scale (radius |$\lt $| 3 kpc) with a shorter time-span affecting the larger length-scales of the disc, which is quantified in terms of changes in |$m=$| 2 and |$m=$| 4 Fourier modes. While the second buckling occurs at larger scales (radius |$\approx$| 6 kpc) affecting the inner disc the most. Finally, we provide observable kinematic signatures (i.e. quadrupolar patterns of the line-of-sight velocities), which can potentially differentiate the successive buckling events. [ABSTRACT FROM AUTHOR]

We present the analysis of three intermediate-mass quiescent galaxies (QGs) with stellar masses of |${\sim} 10^{10}\, \mathrm{M}_{\odot }$| at redshifts |$z\sim 3\!-\!4$| using NIRSpec low-resolution spectroscopy. Utilizing the spectral energy distribution fitting code bagpipes , we confirm these target galaxies are consistent with quiescent population, with their specific star formation rates falling below 2 dex the star-forming main sequence at the same redshifts. Additionally, we identify these QGs to be less massive than those discovered in previous works, particularly prior to the JWST era. Two of our target galaxies exhibit the potentially blended |$\mathrm{ H} \, {\alpha }$|  + [N  ii ] emission line within their spectra with signal-to-noise ratio |${\gt} 5$|⁠. We discuss whether this feature comes from an active galactic nucleus (AGN) or star formation, although future high-resolution spectroscopy is required to reach a conclusion. One of the target galaxies is covered by JWST /NIRCam imaging of the Public Release IMaging for Extragalactic Research survey. Using the 2D profile fitting code galfit , we examine its morphology, revealing a disc-like profile with a Sérsic index of |$n=1.1 \pm 0.1$|⁠. On the size–mass relation, we find a potential distinction between less massive (⁠|$\log _{10}{(M_*/\mathrm{M}_\odot)}\lt 10.3$|⁠) and massive (⁠|$\log _{10}{(M_*/\mathrm{M}_\odot)}\gt 10.3$|⁠) QGs in their evolutionary pathways. The derived quenching time-scales for our targets are less than |$1 \, {\rm Gyr}$|⁠. This may result from these galaxies being quenched by AGN feedback, supporting the AGN scenario of the emission line features. [ABSTRACT FROM AUTHOR]

Using the cosmological simulations IllustrisTNG, we perform a comprehensive analysis of quiescent, massive galaxies at |$z \gtrsim 3$|⁠. The goal is to understand what suppresses their star formation so early in cosmic time, and how other similar mass galaxies remain highly star forming. As a first-order result, the simulations are able to produce massive, quiescent galaxies in this high-redshift regime. We find that active galactic nucleus (AGN) feedback is the primary cause of halting star formation in early, massive galaxies. Not only do the central, supermassive black holes (SMBHs) of the quenched galaxies have earlier seed times, but they also grow faster than in star-forming galaxies. As a result, the quenched galaxies are exposed to AGN feedback for longer, and experience the kinetic, jet mode of the AGN feedback earlier than the star-forming galaxies. The release of kinetic energy reduces inflows of gas while likely maintaining outflows, which keeps a low cold gas fraction and decreases the star formation of the galaxies down to a state of quiescence. In addition to AGN feedback, we also investigate the influence of the large-scale environment. While mergers do not play a significant role in the quenching process, the quenched galaxies tend to reside in more massive haloes and denser regions during their evolution. As this provides a greater initial amount of infalling gas to the galaxies, the large-scale environment can mildly affect the fate of the central SMBH growth and, via AGN feedback, contribute to star formation quenching. [ABSTRACT FROM AUTHOR]

We derive the nitrogen and oxygen abundances in the narrow line regions (NLRs) of a sample of 38 local (⁠|$z \: \lt \: 0.4$|⁠) Seyfert 2 nuclei. For that, we consider narrow optical emission line intensities and direct estimates of the electron temperatures (⁠|$T_{\rm e}$| -method). We obtain a new theoretical expression for the nitrogen ionization correction factor [ICF(⁠|$\rm N^{+}$|⁠)] for NLRs. Applying this new ICF, we unexpectedly find that NLRs and disc H  ii regions exhibit similar ICF distributions. We find nitrogen abundances in the range |$7.6 \: \lt \: \rm 12+log(N/H) \: \lt \: 8.6$| (mean value |$8.06\pm 0.22$|⁠) or |$\rm 0.4 \: \lt \: (N/N_{\odot }) \: \lt 4.7$|⁠ , in the metallicity regime |$8.3 \: \lt \: \rm 12+log(O/H) \: \lt \: 9.0$|⁠. Our results indicate that the dispersion in N/H abundance for a fixed O/H value in AGNs of |$\sim 0.2$| dex agrees with that for disc H  ii regions with similar metallicity. We show that Seyfert 2 nuclei follow a similar (N/O)–(O/H) relation to the one followed by star-forming objects. Finally, we find that active galaxies called as ..nitrogen-loud.. observed at very high redshift (⁠|$z \: \gt \: 5$|⁠) show N/O values in consonance with those derived for local NLRs. This result indicates that the main star-formation event is completed in the early evolution stages of active galaxies. [ABSTRACT FROM AUTHOR]

This paper presents chemical abundances of 12 elements (C, Na, Mg, Al, Si, K, Ca, Ti, V, Cr, Mn, and Fe) for 80 FGK dwarfs in the Pleiades open cluster, which span a temperature range of |$\sim$| 2000 K in T |$_{\rm eff}$|⁠ , using the high-resolution (R |$\sim$| 22 500) near-infrared SDSS (Sloan Digital Sky Survey)-IV/APOGEE (Apache Point Observatory Galactic Evolution Experiment) spectra (⁠|$\lambda$| 1.51–1.69  |$\mu$| m). Using a 1D local thermodynamic equilibrium abundance analysis, we determine an overall metallicity of [Fe/H]  = +0.03 |$\pm$| 0.04 dex, with the elemental ratios [ |$\alpha$| /Fe]  = +0.01 |$\pm$| 0.05, [odd- z /Fe]  = –0.04 |$\pm$| 0.08, and [iron peak/Fe]  = –0.02 |$\pm$| 0.08. These abundances for the Pleiades are in line with the abundances of other open clusters at similar galactocentric distances as presented in the literature. Examination of the abundances derived from each individual spectral line revealed that several of the stronger lines displayed trends of decreasing abundance with decreasing |$T_{\rm eff}$|⁠. The list of spectral lines that yield abundances that are independent of |$T_{\rm eff}$| are presented and used for deriving the final abundances. An investigation into possible causes of the temperature-dependent abundances derived from the stronger lines suggests that the radiative codes and the APOGEE line list we employ may inadequately model van der Waals broadening, in particular in the cooler K dwarfs. [ABSTRACT FROM AUTHOR]

We explore the relations between the gas-phase metallicity radial profiles (few hundred inner parsec) and multiple galaxy properties for 15 Seyfert galaxies from the active galactic nuclei integral field spectroscopy sample using optical integral field unit observations from Gemini Multi-Object Spectrograph (GMOS) and Multi Unit Spectroscopic Explorer (MUSE) processed archival data. The data were selected at |$z \lesssim 0.013$| within black hole mass range |$\left[6\lt \log \left(M_{\rm BH}/{\rm M_\odot } \right)\lt 9\right]$| with moderate 14–150-keV X-ray luminosities |$\left[42\, \lesssim \, \log L_X (\rm erg\, s^{-1})\, \lesssim \, 44\right]$|⁠. We estimated the gas-phase metallicity using the strong-line methods and found mean values for the oxygen-dependent (⁠|$Z \sim 0.75\, \mathrm{Z}_\odot$|⁠) and nitrogen-dependent (⁠|$Z \sim 1.14\, \mathrm{Z}_\odot$|⁠) calibrations. These estimates show excellent agreement with |$\Delta Z \approx 0.19$| and 0.18 dex between the mean values from the two strong-line calibrations for GMOS and MUSE, respectively, consistent with the order of metallicity uncertainty via the strong-line methods. We contend that our findings align with a scenario wherein local Seyferts have undergone seamless gas accretion histories, resulting in positive metallicity profiles over an extended period of time, thereby providing insights into galaxy evolution and the chemical enrichment or depletion of the universe. Additionally, we argue that metal-poor gas inflow from the local interstellar medium and accreted through the circumgalactic medium on to the galaxy systems regulates the star formation processes by diluting their central metallicity and inverting their gas-phase metallicity radial gradients, producing a more prominent anticorrelation between gas-phase metallicity and Eddington ratio. [ABSTRACT FROM AUTHOR]

In this paper, we use hydrodynamic zoom-in simulations of Milky Way-type haloes to explore using dust as an observational tracer to discriminate between cold and warm dark matter (WDM) universes. Comparing a cold and 3.5 keV WDM particle model, we tune the efficiency of galaxy formation in our simulations using a variable supernova rate to create Milky Way systems with similar satellite galaxy populations while keeping all other simulation parameters the same. Cold dark matter (CDM), having more substructure, requires a higher supernova efficiency than WDM to achieve the same satellite galaxy number. These different supernova efficiencies create different dust distributions around their host galaxies, which we generate by post-processing the simulation output with the powderday codebase. Analysing the resulting dust in each simulation, we find |$\sim$| 4.5 times more dust in our CDM Milky Way haloes compared with WDM. The distribution of dust out to R |$_{200\text{c}}$| is then explored, revealing that the WDM simulations are noticeably less concentrated than their CDM counterparts, although differences in substructure complicate the comparison. Our results indicate that dust is a possible unique probe to test theories of dark matter. [ABSTRACT FROM AUTHOR]

Bars are expected to impact the distribution of stellar populations both during bar formation, as they rearrange stars into new orbits, and afterwards, due to the redistribution of star-formation-fuelling gas and transfer of angular momentum. We study the impact of stellar bars on the azimuthal variation of stellar population age, metallicity and mass surface density in |$\sim 1\, 000$| nearby barred galaxies from the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey. Bars have higher stellar mass density (⁠|$0.113^{+0.065}_{-0.067}$|  dex) and are more metal-rich (⁠|$0.028^{+0.033}_{-0.040}$|  dex) than the discs at the same radii. Stellar ages show a variety of bar to interbar contrasts with no consistent trend. The difference in metallicity increases with total stellar mass of the galaxy and distance below the star-forming main sequence. We discuss a combination of potentially responsible processes including kinematic separation, more extended star formation histories and more efficient recycling in bars and at bar-spiral arm connections. Additionally, we observe an offset (⁠|$10^{\circ }$| – |$40^{\circ }$|⁠) of the peak metallicity to the bar major axis in star-forming bars in low-mass galaxies, and more metal-rich regions outside the ends of the bar in long bars and quenched galaxies. Furthermore, there is a subtle trend of lower metallicities on the leading side of spiral arms compared to the trailing side. Finally, we report a spiral arm surface density feature, which could point towards a dominant bar-spiral connection and pitch angle of |$\alpha \sim 25^{\circ }$|⁠. We interpret these features in the context of bar formation and the impact of large-scale gas flows associated with their presence. [ABSTRACT FROM AUTHOR]

Studies have shown that the morphologies of galaxies are substantially transformed following coalescence after a merger, but post-mergers are notoriously difficult to identify, especially in imaging that is shallow or low resolution. We train convolutional neural networks (CNNs) to identify simulated post-merger galaxies in a range of image qualities, modelled after five real surveys: the Sloan Digital Sky Survey (SDSS), the Dark Energy Camera Legacy Survey (DECaLS), the Canada–France Imaging Survey (CFIS), the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP), and the Legacy Survey of Space and Time (LSST). Holding constant all variables other than imaging quality, we present the performance of the CNNs on reserved test set data for each image quality. The success of CNNs on a given data set is found to be sensitive to both imaging depth and resolution. We find that post-merger recovery generally increases with depth, but that limiting 5 |$\sigma$| point-source depths in excess of |$\sim 25$| mag, similar to what is achieved in CFIS, are only marginally beneficial. Finally, we present the results of a cross-survey inference experiment, and find that CNNs trained on a given image quality can sometimes be applied to different imaging data to good effect. The work presented here therefore represents a useful reference for the application of CNNs for merger searches in both current and future imaging surveys. [ABSTRACT FROM AUTHOR]

We study the evolution of the halo occupation distribution (HOD) and galaxy properties of nodes and filamentary structures obtained by disperse from the Illustris TNG300-1 hydrodynamical simulation, in the redshift range |$0 \le z \le 2$|⁠. We compute the HOD in filaments and nodes and fit the HOD parameters to study their evolution for both faint and bright galaxies. In nodes, the number of faint galaxies increases with decreasing redshift in the low-mass haloes, while no significant differences are seen in high-mass haloes. Limiting the HOD to bright galaxies shows that haloes increase in mass more than the number of bright galaxies they accrete. For filaments, no large differences in HOD are found for faint galaxies, although for brighter galaxies the behaviour is the same as in nodes. The HOD parametrization suggests that filaments have no effect on the mass required to host a galaxy (central or satellite), whereas nodes do. The results of the study indicate that with this parametrization, filaments do not seem to affect the stellar mass content of galaxies. In contrast, nodes appear to affect haloes with masses below approximately |$10^{12.5} h^{-1} {\rm M}_{\odot }$| at local redshift. The analysis of the galaxy colour evolution shows a reddening towards lower redshift, although these processes seem to be more efficient in massive haloes, with a strong effect on bright galaxies. The general evolution suggests that the building of galaxy population within haloes is influenced by both the accretion of faint galaxies and the mass growth of the bright ones. [ABSTRACT FROM AUTHOR]

Galaxy clusters provide an avenue to expand our knowledge of cosmology and galaxy evolution. Because it is difficult to accurately measure the total mass of a large number of individual clusters, cluster samples are typically selected using an observable proxy for mass. Selection effects are therefore a key problem in understanding galaxy cluster statistics. We make use of the |$(2.8~\rm {Gpc})^3$| FLAMINGO hydrodynamical simulation to investigate how selection based on X-ray luminosity, thermal Sunyaev–Zeldovich effect or galaxy richness influences the halo mass distribution. We define our selection cuts based on the median value of the observable at a fixed mass and compare the resulting samples to a mass-selected sample. We find that all samples are skewed towards lower mass haloes. For X-ray luminosity and richness cuts below a critical value, scatter dominates over the trend with mass and the median mass becomes biased increasingly low with respect to a mass-selected sample. At |$z\le 0.5$|⁠ , observable cuts corresponding to median halo masses between |$M_\text{500c}=10^{14}$| and |$10^{15}~\rm {{\rm M}_{\odot }}$| give nearly unbiased median masses for all selection methods, but X-ray selection results in biased medians for higher masses. For cuts corresponding to median masses |$\lt 10^{14}$| at |$z\le 0.5$| and for all masses at |$z\ge 1$|⁠ , only Compton-Y selection yields nearly unbiased median masses. Importantly, even when the median mass is unbiased, the scatter is not because for each selection the sample is skewed towards lower masses than a mass-selected sample. Each selection leads to a different bias in secondary quantities like cool-core fraction, temperature, and gas fraction. [ABSTRACT FROM AUTHOR]

This study explores a relationship between the |$\rm {CO}$| luminosity-full width at half-maximum linewidth linear relation (i.e. the |$\rm {CO}$| LFR) and mean galaxy property of the local star-forming galaxy sample in the xCOLDGASS data base, via a mathematical statement. The whole data base galaxies were separated into two subsamples based on their stellar masses and redshifts, being a help to examine the dependence issue of the |$\rm {CO}$| LFR. Selecting the galaxy data with a stringent requirement was also implemented in order to assure the validly of the |$\rm {CO}$| LFR. An algorithm of the linear regression was conducted with the data of the subsample. An assessment about the linear correlation manifested a valid |$\rm {CO}$| LFR occurs in the selected galaxy of the subsample, and the intercept of the |$\rm {CO}$| LFR may be related with the mean galaxy properties such as the molecular gas fraction and galaxy size. For the finding on the intercept of the |$\rm {CO}$| LFR, we aligned that intercept with those galaxy properties via the involvement of a |$\psi$| parameter. On evaluating the |$\psi$| value with our local star-forming galaxy sample, we numerically determined a relationship between the statistical result and the galaxy property in a different stellar mass range. It also shows a possible method on estimating galaxy property. [ABSTRACT FROM AUTHOR]

We study the contribution of various astrophysical events asymptotic giant branch (AGB stars, core collapse and thermonuclear supernovae, neutron star mergers, and collapsars) to the abundances of elements both up to and heavier than the iron peak in a Local Group dwarf irregular galaxy, Wolf–Lundmark–Melotte (WLM). Its star formation history has been recently determined by observations with the JWST , and we use it to estimate the occurrence of the astrophysical sources. The rates of the gas accretion and the outflow are roughly determined based on the stellar metallicity distribution, the oxygen abundance of H  ii regions, and the gas fraction. As discussed in the literature, the difference in time-scales on which the astrophysical events release the nucleosynthesis products is seen in the occurrence of the events and the evolution of abundance ratios. WLM has an extended star formation history and massive stars are recently and currently formed. Thus, the contribution of rotating massive stars through the weak s-process appears in the abundance ratios of light trans-iron elements to iron at later time of the evolution. [ABSTRACT FROM AUTHOR]

Here, we present high spectral resolution |${\it JWST}$| NIRSpec observations of GN 42437, a low-mass (log(M |$_\ast /{\rm M}_\odot)=7.9$|⁠), compact (⁠|$r_e \lt 500$| pc), extreme starburst galaxy at |$z=5.59$| with 13 emission-line detections. GN 42437 has a low metallicity (5–10 per cent Z |$_\odot$|⁠) and its rest-frame H |$\alpha$| equivalent width suggests nearly all of the observed stellar mass formed within the last 3 Myr. GN 42437 has an extraordinary 7 |$\sigma$| significant [Ne  v ] 3427 Å detection. The [Ne  v ] line has a rest-frame equivalent width of |$11\pm 2$| Å, [Ne  v ]/H |$\alpha =0.04\pm 0.007$|⁠ , [Ne  v ]/[Ne  iii ] 3870Å |$= 0.26\pm 0.04$|⁠ , and [Ne  v ]/He  ii 4687Å |$ = 1.2\pm 0.5$|⁠. Ionization from massive stars, shocks, or high-mass X-ray binaries cannot simultaneously produce these [Ne  v ] and other low-ionization line ratios. Reproducing the complete nebular structure requires both massive stars and accretion on to a black hole. We do not detect broad lines nor do the traditional diagnostics indicate that GN 42437 has an accreting black hole. Thus, the very high-ionization emission lines powerfully diagnose faint narrow-line black holes at high redshift. We approximate the black hole mass in a variety of ways as log(M |$_{\rm BH}/{\rm M}_\odot) \sim 5{-}7$|⁠. This black hole mass is consistent with local relations between the black hole mass and the observed velocity dispersion, but significantly more massive than the stellar mass would predict. Very high-ionization emission lines may reveal samples to probe the formation and growth of the first black holes in the universe. [ABSTRACT FROM AUTHOR]

We present a new method to determine the star formation rate density (SFRD) of the Universe at |$z \gtrsim 5$| that includes the contribution of dust-obscured star formation. For this purpose, we use a [C  ii ] (158 |$\mu$| m) selected sample of galaxies serendipitously identified in the fields of known |$z\gtrsim 4.5$| objects to characterise the fraction of obscured star formation rate (SFR). The advantage of a [C  ii ] selection is that our sample is SFR-selected, in contrast to an ultraviolet (UV)-selection that would be biased towards unobscured star formation. We obtain a sample of 23 [C  ii ] emitters near star-forming (SF) galaxies and quasi-stellar objects (QSOs) – three of which we identify for the first time – using previous literature and archival Atacama Large Millimeter/submillimeter Array data. 18 of these serendipitously identified galaxies have sufficiently deep rest-UV data and are used to characterise the obscured fraction of the star formation in galaxies with SFRs |$\gtrsim 30\ \text{M}_{\odot } \ \text{yr}^{-1}$|⁠. We find that [C  ii ] emitters identified around SF galaxies have |$\approx$| 63 per cent of their SFR obscured, while [C  ii ] emitters around QSOs have |$\approx$| 93 per cent of their SFR obscured. By forward modelling existing wide-area UV luminosity function (LF) determinations, we derive the intrinsic UV LF using our characterisation of the obscured SFR. Integrating the intrinsic LF to |$M_{\mathrm{ UV}}$| = |$-$| 20, we find that the obscured SFRD contributes to |$\gt 3~{{\ \rm per\ cent}}$| and |$\gt 10~{{\ \rm per\ cent}}$| of the total SFRD at |$z \sim 5$| and |$z \sim 6$| based on our sample of companions galaxies near SF galaxies and QSOs, respectively. Our results suggest that dust obscuration is not negligible at |$z\gtrsim 5$|⁠ , further underlining the importance of far-infrared observations of the |$z\gtrsim 5$| Universe. [ABSTRACT FROM AUTHOR]

Stellar mass and specific angular momentum are two properties of a galaxy that are directly related to its formation history, and hence morphology. In this work, the tight planar relationship between stellar specific angular momentum (⁠|$j_*$|⁠), mass (⁠|$M_*$|⁠), and mean effective surface brightness (⁠|$\left\langle \mu _\mathrm{eff}\right\rangle $|⁠) that was recently constrained using ALFALFA (Arecibo Legacy Fast ALFA) galaxies is measured more accurately using galaxies from the simba cosmological simulation. The distribution of 179 simba galaxies in |$\log _{10}j_* \!-\! \log _{10}M_*$| − |$\left\langle \mu _\mathrm{eff}\right\rangle $| space is shown to be very tightly planar with |$j_*\propto M_*^{0.694}$| and the distribution of perpendicular distances between the galaxies and the plane being approximately Gaussian with |$\mathrm{RMS}=0.057$|  dex. The parametrized distribution is used with existing |$j_*$| and |$\left\langle \mu _\mathrm{eff}\right\rangle $| measurements of 3607 ALFALFA galaxies and 84 SPARC (Spitzer Photometry and Accurate Rotation Curves) galaxies to reliably predict their published stellar masses to within |$\sim 0.1$| –0.2 dex over several decades of stellar mass. Thus, this work presents a new method of easily generating accurate galaxy stellar mass estimates for late-type galaxies and provides a new measurement of the fundamental link between galaxy morphology, mass, and angular momentum. [ABSTRACT FROM AUTHOR]

Galaxy properties are known to be affected by their environment. This is well established for the extremes of the density scales, between the high-density cluster environment and the low-density field. It is, however, not fully understood how the intermediate-density regime of cosmic web filaments affects galaxy evolution. We investigate this environmental effect using a mass complete sample of 23 441 galaxies in the Sloan Digital Sky Survey DR8 Main Galaxy Sample (⁠|${M}_{\text{Stellar}} \gt 10^{9.91} \text{M}_{\odot }$|⁠). We define six environments, probing different density regimes and representing unique stages in the structure formation process, comparing the differences in star formation activity and morphology between them. We find that galaxies in filaments tend to be less star-forming and favour more early-type morphologies than those in the field. These differences persist when considering stellar mass-matched samples, suggesting that this is a consequence of the environment. We further investigate whether these trends are a result of the large-scale or local environment through constructing samples matched both in stellar mass and local galaxy density. We find that when also matching in local galaxy density, the differences observed between the filament and field population vanishes, concluding that the environmental effect of filaments can be entirely parametrized by a local galaxy density index. We find that differences can still be seen in comparisons with the interiors of clusters, suggesting these are unique environments which can impart additional physical processes not characterized by local galaxy density. [ABSTRACT FROM AUTHOR]

We use resolved spectroscopy from MaNGA to investigate the significance of both local and global properties of galaxies to the cessation of star formation at kpc scales. Quenched regions are identified from a sample of isolated disk galaxies by a single-parameter criterion D n (4000) - log EW(H α) > 1.6 − log 2 = 1.3 , and are divided into gas-rich quenched regions (GRQRs) and gas-poor quenched regions according to the surface density of cold gas (Σgas). Both types of quenched regions tend to be hosted by non-AGN galaxies with relatively high mass (M * ≳ 1010 M ⊙) and red colors (NUV − r ≳ 3), as well as low star formation rate and high central density at fixed mass. They span wide ranges in other properties including structural parameters that are similar to the parent sample, indicating that the conditions responsible for quenching in gas-rich regions are largely independent of the global properties of galaxies. We train random forest classifiers and regressors for predicting quenching in our sample with 15 local/global properties. Σ* is the most important property for quenching, especially for GRQRs. These results strongly indicate the important roles of low-mass hot evolved stars, which are numerous and long-lived in quenched regions and can provide substantial radiation pressure to support the surrounding gas against gravitational collapse. The different feature importance for quenching, as found previously by A. F. L. Bluck et al., is partly due to the different definitions of quenched regions, particularly the different requirements on EW(H α). [ABSTRACT FROM AUTHOR]

The stellar shells surrounding an elliptical galaxy, as remnants of a dwarf galaxy disrupted during merging, reveal the distribution of energy and angular momentum of the progenitor dwarf galaxy. We develop a semi-analytical model to describe the changes in energy Δ E i and angular momentum Δ Lz i for particles during the first infall. We show that these changes, induced by the self-gravity of the progenitor, are important in broadening the initial energy distribution of the Plummer or Hernquist progenitor model. Consequently, these changes are crucial in shaping the shells. In the freefall stage following the disintegration of the progenitor potential, particles are no longer bound by self-gravity but move within the gravitational potential of the target galaxy. We investigate the relationship between the radial period and the energy of particles undergoing radial motion. We show that an accurate model of the energy range of the dwarf galaxy at disruption is essential to predict the number of observable shells. [ABSTRACT FROM AUTHOR]

Relic galaxies, the oldest ultra-compact massive galaxies (UCMGs), contain almost exclusively 'pristine' stars formed during an intense star formation (SF) burst at high redshift. As such, they allow us to study in detail the early mechanism of galaxy assembly in the Universe. Using the largest catalogue of spectroscopically confirmed UCMGs for which a degree of relicness (DoR) had been estimated, the INSPIRE catalogue, we investigate whether or not relics prefer dense environments. The objective of this study is to determine if the DoR, which measures how extreme the SF history was, and the surrounding environment are correlated. In order to achieve this goal, we employ the AMICO galaxy cluster catalogue to compute the probability for a galaxy to be a member of a cluster, and measure the local density around each UCMG using machine learning-based photometric redshifts. We find that UCMGs can reside both in clusters and in the field, but objects with very low DoR (⁠|$\lt 0.3$|⁠ , i.e. a relatively extended SF history) prefer underdense environments. We additionally report a correlation between the DoR and the distance from the cluster centre: more extreme relics, when located in clusters, tend to occupy the more central regions of them. We finally outline potential evolution scenarios for UCMGs at different DoR to reconcile their presence in both clusters and field environments. [ABSTRACT FROM AUTHOR]

Tidal features are a key observable prediction of the hierarchical model of galaxy formation and contain a wealth of information about the properties and history of a galaxy. Modern wide-field surveys such as LSST and Euclid will revolutionize the study of tidal features. However, the volume of data will prohibit visual inspection to identify features, thereby motivating a need to develop automated detection methods. This paper presents a visual classification of ∼2000 galaxies from the DECaLS survey into different tidal feature categories: arms, streams, shells , and diffuse. We trained a convolutional neural network (CNN) to reproduce the assigned visual classifications using these labels. Evaluated on a testing set where galaxies with tidal features were outnumbered |$\sim 1:10$|⁠ , our network performed very well and retrieved a median |$98.7\pm 0.3$|⁠ , |$99.1\pm 0.5$|⁠ , |$97.0\pm 0.8$|⁠ , and |$99.4^{+0.2}_{-0.6}$|  per  cent of the actual instances of arm, stream, shell , and diffuse features respectively for just 20 per cent contamination. A modified version that identified galaxies with any feature against those without achieved scores of |$0.981^{+0.001}_{-0.003}$|⁠ , |$0.834^{+0.014}_{-0.026}$|⁠ , |$0.974^{+0.008}_{-0.004}$|⁠ , and |$0.900^{+0.073}_{-0.015}$| for the accuracy, precision, recall, and F1 metrics, respectively. We used a gradient-weighted class activation mapping analysis to highlight important regions on images for a given classification to verify the network was classifying the galaxies correctly. This is the first demonstration of using CNNs to classify tidal features into sub-categories, and it will pave the way for the identification of different categories of tidal features in the vast samples of galaxies that forthcoming wide-field surveys will deliver. [ABSTRACT FROM AUTHOR]

We investigate galaxy sizes at redshift |$z\gtrsim 6$| with the cosmological radiation-magnetohydrodynamic simulation suite thesan(-hr). These simulations simultaneously capture reionization of the large-scale intergalactic medium and resolved galaxy properties. The intrinsic sizes (⁠|$r^{\ast }_{1/2}$|⁠) of simulated galaxies increase moderately with stellar mass at |$M_{\ast } \lesssim 10^{8}{\, \rm M_\odot}$| and decrease fast at larger masses, resulting in a hump feature at |$M_{\ast }\sim 10^{8}{\, \rm M_\odot}$| that is insensitive to redshift. Low-mass galaxies are in the initial phase of size growth and are better described by a spherical shell model with feedback-driven outflows competing with the cold inflowing gas streams. In contrast, massive galaxies fit better with the disc formation model. They generally experience a phase of rapid compaction and gas depletion, likely driven by internal disc instability rather than external processes. We identify four compact quenched galaxies in the |$(95.5\, {\rm cMpc})^{3}$| volume of thesan-1 at |$z\simeq 6$| and their quenching follows reaching a characteristic stellar surface density akin to the massive compact galaxies at cosmic noon. Compared to observations, we find that the median ultraviolet effective radius (⁠|$R^{\rm UV}_{\rm eff}$|⁠) of simulated galaxies is at least three times larger than the observed ones at |$M_{\ast }\lesssim 10^{9}{\, \rm M_\odot}$| or |$M_{\rm UV}\gtrsim -20$| at |$6 \lesssim z \lesssim 10$|⁠. The population of compact galaxies (⁠|$R^{\rm UV}_{\rm eff}\lesssim 300\, {\rm pc}$|⁠) galaxies at |$M_{\ast }\sim 10^{8}{\, \rm M_\odot}$| is missing in our simulations. This inconsistency persists across many other cosmological simulations with different galaxy formation models and demonstrates the potential of using galaxy morphology to constrain physics of galaxy formation at high redshifts. [ABSTRACT FROM AUTHOR]

Ongoing deep integral-field spectroscopy (IFS) observations of disc galaxies provide opportunities for comparison with the Milky Way (MW) to understand galaxy evolution. However, such comparisons are marred by many challenges such as selection effects, differences in observations and methodology, and proper validation of full-spectrum fitting methods. In this study, we present a novel code GalCraft to address these challenges by generating mock IFS data cubes of the MW using simple stellar population models and a mock MW stellar catalogue derived from E-galaxia. We use the widely adopted full-spectrum fitting code ppxf to investigate the ability to recover kinematics and stellar populations for an edge-on mock MW IFS observation. We confirm that differences in kinematics, mean age, |$[\mathrm{M/H}]$|⁠ , and |$[\mathrm{\alpha /Fe}]$| between thin and thick discs can be distinguished. However, the age distribution is overestimated in the ranges between |$2{-}4$| and |$12{-}14$|  Gyr compared to the expected values. This is likely due to the age spacing and degeneracy of SSP templates. We find systematic offsets in the recovered kinematics due to insufficient spectral resolution and the variation of line-of-sight velocity distribution with age and |$[\mathrm{M/H}]$|⁠. With future higher resolution and multi- |$[\mathrm{\alpha /Fe}]$| simple stellar population templates, GalCraft will be useful to validate key signatures such as |$[\mathrm{\alpha /Fe}]$| – |$[\mathrm{M/H}]$| distribution at different R and |$|z|$| and potentially infer radial migration and kinematic heating efficiency to study detailed chemodynamical evolution of MW-like galaxies. [ABSTRACT FROM AUTHOR]

We present an analysis of 152 355 radio sources identified in the second data release of the LOFAR Two Metre Sky Survey (LoTSS-DR2) with Sloan Digital Sky Survey (SDSS) spectroscopic redshifts in the range |$0.00 \lt z \lt 0.57$|⁠. Using Monte Carlo simulations, we determine the reliability of each source exhibiting an excess in radio luminosity relative to that predicted from their H |$\alpha$| emission, and, for a subset of 124 023 sources we combine this measurement with a full BPT analysis. Using these two independent diagnostics, we determine the reliability of each source hosting a supermassive black hole of high or low Eddington-scaled accretion rate, and combine the measurements to determine the reliability of sources belonging to each of four physical classes of objects: star-forming galaxies (SFGs), radio-quiet active galactic nuclei (RQAGN), and high- or low-excitation radio galaxies (HERGs or emission-line LERGs). The result is a catalogue that enables user-defined samples of radio sources with a reliability threshold suited to their science goal, for example prioritizing purity or completeness. Here, we select high-confidence samples of radio sources (>90 per cent reliability) to report: 38 588 radio-excess AGNs in the LoTSS-DR2 sample (362 HERGs, and 12 648 emission-line LERGs), together with 38 729 SFGs, and 18 726 RQAGN. We validate these results through comparison to literature using independent emission-line measurements, and to widely adopted WISE photometric selection techniques. While our use of SDSS spectroscopy limits our current analysis to |$\sim 4$|  per cent of the LoTSS-DR2 catalogue, our method is directly applicable to data from the forthcoming WEAVE-LOFAR survey, which will obtain over a million spectra of 144 MHz selected sources. [ABSTRACT FROM AUTHOR]

The circular velocity function (CVF) of galaxies is a fundamental test of the Lambda cold dark matter (⁠|$\Lambda$| CDM) paradigm as it traces the variation of galaxy number densities with circular velocity (⁠|$v_{\rm {circ}}$|⁠), a proxy for dynamical mass. Previous observational studies of the CVF have either been based on H  i -rich galaxies, or encompassed low-number statistics and probed narrow ranges in |$v_{\rm {circ}}$|⁠. We present a benchmark computation of the CVF between |$100\,{\text{and}}\,350\ \rm {km\ s^{-1}}$| using a sample of 3527 nearby Universe galaxies, representative for stellar masses between |$10^{9.2}\,{\text{and}}\,10^{11.9} \rm {{\rm M}_{\odot }}$|⁠. We find significantly larger number densities above 150 |$\rm {km\ s^{-1}}$| compared to results from H  i surveys, pertaining to the morphological diversity of our sample. Leveraging the fact that circular velocities are tracing the gravitational potential of haloes, we compute the halo mass function (HMF), covering |$\sim$| 1 dex of previously unprobed halo masses (⁠|$10^{11.7}{\!-\!}10^{12.7} \rm {{\rm M}_{\odot }}$|⁠). The HMF for our sample, representative of the galaxy population with |$M_{200}\geqslant 10^{11.35} \rm {{\rm M}_{\odot }}$|⁠ , shows that spiral morphologies contribute 67 per cent of the matter density in the nearby Universe, while early types account for the rest. We combine our HMF data with literature measurements based on H  i kinematics and group/cluster velocity dispersions. We constrain the functional form of the HMF between |$10^{10.5}-10^{15.5} \rm {{\rm M}_{\odot }}$|⁠ , finding a good agreement with |$\Lambda$| CDM predictions. The halo mass range probed encompasses 72 |$\substack{+5 -6}$| per cent (⁠|$\Omega _{\rm {M,10.5-15.5}} = 0.227 \pm 0.018$|⁠) of the matter density in the nearby Universe; 31 |$\substack{+5 -6}$| per cent is accounted for by haloes below |$10^{12.7}\rm {{\rm M}_{\odot }}$| occupied by a single galaxy. [ABSTRACT FROM AUTHOR]

We introduce a GPU-accelerated hybrid hydro/ N -body code (Enzo-N) designed to address the challenges of concurrently simulating star clusters and their parent galaxies. This task has been exceedingly challenging, primarily due to the considerable computational time required, which stems from the substantial scale difference between galaxies (∼0.1 Mpc) and star clusters (∼parsecs). Yet, this significant scale separation means that particles within star clusters perceive those outside the star cluster in a semistationary state. By leveraging this aspect, we integrate a direct N -body code (Nbody6++GPU) into a cosmological (magneto)hydrodynamic code (Enzo) through utilization of the semistationary background acceleration approximation. We solve the dynamics of particles within star clusters using a direct N -body solver with regularization for few-body interactions, while evolving particles outside—dark matter, gas, and stars—using a particle-mesh gravity solver and hydrodynamic methods. We demonstrate that Enzo-N successfully simulates the coevolution of star clusters and their parent galaxies, capturing phenomena such as core collapse of the star cluster and tidal stripping due to galactic tides. This comprehensive framework opens up new possibilities for studying the evolution of star clusters within galaxies, offering insights that were previously inaccessible. [ABSTRACT FROM AUTHOR]

Mergers of and interactions between galaxies imprint a wide diversity of morphological, dynamical, and chemical characteristics in stellar halos and tidal streams. Measuring these characteristics elucidates aspects of the progenitors of the galaxies we observe today. The M81 group is the perfect galaxy group to understand the past, present, and future of a group of galaxies in the process of merging. Here, we measure the end of star formation (t 90) and metallicity ([M/H]) of the stellar halo of M82 and the eastern tidal stream of NGC 3077 to: (1) test the idea that M82 possesses a genuine stellar halo, formed before any interaction with M81; (2) determine if NGC 3077's tidal disruption is related to the star formation history in its tails; and (3) create a timeline of the assembly history of the central trio in the M81 group. We argue that M82 possesses a genuine, metal-poor ([M/H] ∼ −1.62 dex) stellar halo, formed from the merger of a small satellite galaxy roughly 6.6 Gyr ago. We also find that the stars present in NGC 3077's tails formed before tidal disruption with M81, and possess a roughly uniform metallicity as shown in S. Okamoto et al., implying that NGC 3077's progenitor had significant population gradients. Finally, we present a timeline of the central trio's merger/interaction history. [ABSTRACT FROM AUTHOR]

The first generations of stars left their chemical fingerprints on metal-poor stars in the Milky Way and its surrounding dwarf galaxies. While instantaneous and homogeneous enrichment implies that groups of conatal stars should have the same element abundances, small amplitudes of abundance scatter are seen at fixed [Fe/H]. Measurements of intrinsic abundance scatter have been made with small high-resolution spectroscopic data sets where measurement uncertainty is small compared to this scatter. In this work, we present a method to use mid-resolution survey data, which have larger errors, to make this measurement. Using APOGEE Data Release 17, we calculate the intrinsic scatter of Al, O, Mg, Si, Ti, Ni, and Mn relative to Fe for 333 metal-poor stars across six classical dwarf galaxies around the Milky Way, and 1604 stars across 19 globular clusters (GCs). We calibrate the reported abundance errors in bins of signal-to-noise ratio and [Fe/H] using a high-fidelity halo data set. Applying these calibrated errors to the APOGEE data, we find small amplitudes of average intrinsic abundance scatter in dwarf galaxies ranging from 0.03 to 0.09 dex, with a median value of 0.047 dex. For the GCs, we find intrinsic scatters ranging from 0.01 to 0.11 dex, with particularly high scatter for Al and O. Our measurements of intrinsic abundance scatter place important upper bounds, which are limited by our calibration, on the intrinsic scatter in these systems, as well as constraints on their underlying star formation history and mixing that we can look to simulations to interpret. [ABSTRACT FROM AUTHOR]

We present Lightcurve Anomaly Identification and Similarity Search (LAISS), an automated pipeline to detect anomalous astrophysical transients in real-time data streams. We deploy our anomaly detection model on the nightly Zwicky Transient Facility (ZTF) Alert Stream via the ANTARES broker, identifying a manageable ∼1–5 candidates per night for expert vetting and coordinating follow-up observations. Our method leverages statistical light-curve and contextual host galaxy features within a random forest classifier, tagging transients of rare classes (spectroscopic anomalies), of uncommon host galaxy environments (contextual anomalies), and of peculiar or interaction-powered phenomena (behavioral anomalies). Moreover, we demonstrate the power of a low-latency (∼ms) approximate similarity search method to find transient analogs with similar light-curve evolution and host galaxy environments. We use analogs for data-driven discovery, characterization, (re)classification, and imputation in retrospective and real-time searches. To date, we have identified ∼50 previously known and previously missed rare transients from real-time and retrospective searches, including but not limited to superluminous supernovae (SLSNe), tidal disruption events, SNe IIn, SNe IIb, SNe I-CSM, SNe Ia-91bg-like, SNe Ib, SNe Ic, SNe Ic-BL, and M31 novae. Lastly, we report the discovery of 325 total transients, all observed between 2018 and 2021 and absent from public catalogs (∼1% of all ZTF Astronomical Transient reports to the Transient Name Server through 2021). These methods enable a systematic approach to finding the "needle in the haystack" in large-volume data streams. Because of its integration with the ANTARES broker, LAISS is built to detect exciting transients in Rubin data. [ABSTRACT FROM AUTHOR]

The multiphase circumgalactic medium (CGM) hosts critical processes that affect galaxy evolution such as accretion and outflows. We searched for evidence of these phenomena by using the EW co-rotation fraction (⁠|$f_{\rm EWcorot}$|⁠) to study the kinematic connection between the multiphase CGM and host galaxy rotation. We examined CGM absorption from Hubble Space Telescope / Cosmic Origins Spectrograph (including, but not limited to, Si  ii , C  ii , Si  iii , C  iii , and O  vi) within |$21\le D\le ~276$| kpc of 27 galaxies. We find the median |$f_{\rm EWcorot}$| for all ions is consistent within errors and the |$f_{\rm EWcorot}$| increases with increasing N |$({{{\rm H} \rm{\small I}}})$|⁠. The |$f_{\rm EWcorot}$| of lower ionization gas decreases with increasing |$D/R_{\rm vir}$|⁠ , while O  vi and H  i are consistent with being flat. The |$f_{\rm EWcorot}$| varies minimally as a function of azimuthal angle and is similar for all ions at a fixed azimuthal angle. The larger number of O  vi detections enabled us to investigate where the majority of co-rotating gas is found. Highly co-rotating O  vi primarily resides along the galaxies' major axis. Looking at the |$f_{\rm EWcorot}$| as a function of ionization potential (⁠|${{\rm d}{({f_{\rm EWcorot}})}}/{{\rm d}{(\rm eV)}}$|⁠), we find a stronger co-rotation signature for lower ionization gas. There are suggestions of a connection between the CGM metallicity and major axis co-rotation where low-ionization gas with higher |$f_{\rm EWcorot}$| exhibits lower metallicity and may trace large-scale filamentary inflows. Higher ionization gas with higher |$f_{\rm EWcorot}$| exhibits higher metallicity and may instead trace co-planar recycled gas accretion. Our results stress the importance of comparing absorption originating from a range of ionization phases to differentiate between various gas flow scenarios. [ABSTRACT FROM AUTHOR]

Most star formation in the local Universe occurs in spiral galaxies, but their origin remains an unanswered question. Various theories have been proposed to explain the development of spiral arms, each predicting different spatial distributions of the interstellar medium. This study maps the star formation rate (SFR) and gas-phase metallicity of nine spiral galaxies with the TYPHOON survey to test two dominating theories: density wave theory and dynamic spiral theory. We discuss the environmental effects on our galaxies, considering reported environments and merging events. Taking advantage of the large field of view covering the entire optical disc, we quantify the fluctuation of SFR and metallicity relative to the azimuthal distance from the spiral arms. We find higher SFR and metallicity in the trailing edge of NGC 1365 (by 0.117 and 0.068 dex, respectively) and NGC 1566 (by 0.119 and 0.037 dex, respectively), which is in line with density wave theory. NGC 2442 shows a different result with higher metallicity (0.093 dex) in the leading edge, possibly attributed to an ongoing merging. The other six spiral galaxies show no statistically significant offset in SFR or metallicity, consistent with dynamic spiral theory. We also compare the behaviour of metallicity inside and outside the corotation radius (CR) of NGC 1365 and NGC 1566. We find comparable metallicity fluctuations near and beyond the CR of NGC 1365, indicating gravitational perturbation. NGC 1566 shows the greatest fluctuation near the CR, in line with the analytic spiral arms. Our work highlights that a combination of mechanisms explains the origin of spiral features in the local Universe. [ABSTRACT FROM AUTHOR]

Using several variants of the cosmological simba simulations, we investigate the impact of different feedback prescriptions on the cosmic star formation history. Adopting a global-to-local approach, we link signatures seen in global observables, such as the star formation rate density (SFRD) and the galaxy stellar mass function (GSMF), to feedback effects in individual galaxies. We find a consistent picture: stellar feedback mainly suppresses star formation below halo masses of |$M_{\rm H} = 10^{12} \rm \, {\rm M}_{\odot }$| and before |$z = 2$|⁠ , whereas AGN feedback quenches the more massive systems after |$z = 2$|⁠. Among simba 's AGN feedback modes, AGN jets are the dominant quenching mechanism and set the shape of the SFRD and the GSMF at late times. AGN-powered winds only suppress the star formation rate in intermediate-mass galaxies (⁠|$M_{\rm \star } = 10^{9.5 - 10} \rm \, {\rm M}_{\odot }$|⁠), without affecting the overall stellar mass-assembly significantly. At late times, the AGN X-ray feedback mode mainly quenches residual star formation in massive galaxies. Our analysis reveals that this mode is also necessary to produce the first fully quenched galaxies before |$z=2$|⁠ , where the jets alone are inefficient. These initially highly star-forming galaxies contain relatively large black holes, likely strengthening the X-ray-powered heating and ejection of gas from the dense, central region of galaxies. Such extra heating source quenches the local star formation and produces a more variable accretion rate. More generally, this effect also causes the break down of correlations between the specific star formation rate, the accretion rate and the black hole mass. [ABSTRACT FROM AUTHOR]

We report ultra-deep, medium-resolution spectroscopic observations for four quiescent galaxies with log |$_{10}(M_*/\mathrm{M_\odot })\gt 11$| at |$3 \lt z \lt 5$|⁠. These data were obtained with JWST NIRSpec as part of the Early eXtragalactic Continuum and Emission Line Science (EXCELS) survey, which we introduce in this work. The first two galaxies are newly selected from PRIMER UDS imaging, both at |$z=4.62$| and separated by 860 pkpc on the sky, within a larger structure for which we confirm several other members. Both formed at |$z\simeq 8-10$|⁠. These systems could plausibly merge by the present day to produce a local massive elliptical galaxy. The other two ultra-massive quiescent galaxies are previously known at |$z=3.99$| and 3.19, with the latter (ZF-UDS-7329) having been the subject of debate as potentially too old and too massive to be accommodated by the |$\Lambda$| -CDM halo-mass function. Both exhibit high stellar metallicities, and for ZF-UDS-7329 we are able to measure the |$\alpha -$| enhancement, obtaining [Mg/Fe] = |$0.42^{+0.19}_{-0.17}$|⁠. We finally evaluate whether these four galaxies are consistent with the |$\Lambda$| -CDM halo-mass function using an extreme value statistics approach. We find that the |$z=4.62$| objects and the |$z=3.19$| object are unlikely within our area under the assumption of standard stellar fractions (⁠|$f_*\simeq 0.1-0.2$|⁠). However, these objects roughly align with the most massive galaxies expected under the assumption of 100 per cent conversion of baryons to stars (⁠|$f_*$| =1). Our results suggest extreme galaxy formation physics during the first billion years, but no conflict with |$\Lambda$| -CDM cosmology. [ABSTRACT FROM AUTHOR]

The diffuse stellar component of galaxy clusters made up of intergalactic stars is termed the intracluster light (ICL). Although there is a developing understanding of the mechanisms by which the ICL is formed, no strong consensus has yet been reached on which objects the stars of the ICL are primarily sourced from. We investigate the assembly of the ICL starting approximately 10 Gyr before |$z=0$| in 11 galaxy clusters (halo masses between |$\sim 1\times 10^{14}$| and |$\sim 7\times 10^{14}$|  M |$_{\odot }$| at |$z\approx 0$|⁠) in the Horizon-AGN simulation. By tracking the stars of galaxies that fall into these clusters past cluster infall, we are able to link almost all of the |$z\approx 0$| ICL back to progenitor objects. Satellite stripping, mergers, and pre-processing are all found to make significant contributions to the ICL, but any contribution from in situ star formation directly into the ICL appears negligible. Even after compensating for resolution effects, we find that approximately 90 per cent of the stacked ICL of the 11 clusters that is not pre-processed should come from galaxies infalling with stellar masses above |$10^{9}$|  M |$_{\odot }$|⁠ , with roughly half coming from infalling galaxies with stellar masses within half a dex of |$10^{11}$|  M |$_{\odot }$|⁠. The fact that the ICL appears largely sourced from such massive objects suggests that the ICL assembly of any individual cluster may be principally stochastic. [ABSTRACT FROM AUTHOR]

We present an analysis of the cold gas phase in a low-metallicity starburst generated in a high-resolution hydrodynamical simulation of a gas-rich dwarf galaxy merger as part of the griffin project. The simulations resolve (4 M |$_\odot$| gas phase mass resolution, |$\sim$| 0.1 pc spatial resolution) the multiphase interstellar medium with a non-equilibrium chemical heating/cooling network at temperatures below 10 |$^4$|  K. Massive stars are sampled individually and interact with the interstellar medium (ISM) through the formation of H  ii regions and supernova explosions. In the extended starburst phase, the ISM is dominated by cold (⁠|$T_\mathrm{gas} < 300$|  K) filamentary clouds with self-similar internal structures. The clouds have masses of |$10^{2.6}$| – |$10^{5.6}$|  M |$_\odot$| with a power-law mass function, |$\mathrm{ d}N/\mathrm{ d}M \propto M^\alpha$| with |$\alpha = -1.78 (\,\pm \,0.08)$|⁠. They also follow the Larson relations, in good agreement with observations. We trace the lifecycle of the cold clouds and find that they follow an exponential lifetime distribution and an e-folding time of |$\sim$| 3.5 Myr. Clouds with peak masses below |$10^4$|  M |$_\odot$| follow a power-law relation with their average lifetime |$\tau _\mathrm{life} \propto M^{0.3}_\mathrm{max}$| which flattens out for higher cloud masses at |$< 10$|  Myr. A similar relation exists between cloud size at peak mass and lifetime. This simulation of the evolution of a realistic galactic cold cloud population supports the rapid formation and disruption of star-forming clouds by stellar radiation and supernovae on a time-scale less than 10 Myr. [ABSTRACT FROM AUTHOR]