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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]

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]

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]

We present a novel method to characterize dust depletion, namely, the depletion of metals into dust grains. We used observed correlations among relative abundances combining a total of 17 metals in diverse galactic environments, including the Milky Way (MW), Large Magellanic Cloud (LMC), Small Magellanic Cloud (SMC), and damped Lyman-α absorbers (DLAs) towards quasars and gamma-ray bursts (GRBs). We only considered the relative abundances of metals that qualify as tracers of dust and we used all available dust tracers. We find linear correlations among all studied dust tracers in a multidimensional space, where each dimension corresponds to an individual dust tracer. The fit to the linear correlations among the dust tracers describes the tendencies of different elements when depleting into dust grains. We determined the overall strength of dust depletion, ∆, along individual lines of sight, based on the correlations among different dust tracers. We avoided any preference for specific dust tracers or any other assumptions by including all available dust tracers in this multidimensional space. We also determined the dust depletion of Kr, C, O, Cl, P, Zn, Ge, Mg, Cu, Si, Fe, Ni, and Ti. Finally, we offer simple guidelines for the application of the method to the study of the observed patterns of abundances and relative abundances. This has allowed for a straightforward determination of the overall strength of depletion and the dust depletion of individual elements. We also obtained an estimate for the gas-phase metallicity and identified any additional deviations due to the nucleosynthesis of specific stellar populations. Thus, we have established a unified methodology for characterizing dust depletion across cosmic time and diverse galactic environments, offering a valuable new approach to the study of dust depletion in studies of the chemical evolution of galaxies. [ABSTRACT FROM AUTHOR]

The well-known bimodal distribution of Milky Way disk stars in the [α/Fe]–metallicity plane is often used to define thick and thin disks. In external edge-on galaxies, there have been attempts to identify this type of bimodality using integral field spectroscopy (IFS) data. However, for unresolved stellar populations, observations only contain integrated information, making these studies challenging. We assessed the ability to recover chemical bimodalities in IFS observations of edge-on galaxies, using 24 Milky Way-mass galaxies from the AURIGA zoom-in cosmological simulations. We first analyzed the distribution of single stellar particles in the [Mg/Fe]–[Fe/H] plane, finding that bimodality is frequent but not ubiquitous and often unclear. Then we produced mock IFS [Mg/Fe] and [Fe/H] maps of galaxies seen edge on, and considered integrated stellar-population properties (projected and spatially binned). We investigated how the distribution of stars in the [Mg/Fe]–[Fe/H] plane is affected by edge-on projection and spatial binning. Bimodality is preserved, while distributions change their shapes. Naturally, broad distributions of individual star particles are narrowed into smaller [Mg/Fe] and [Fe/H] ranges for spatial bins. We observe continuous distributions from high [Mg/Fe] and low [Fe/H], to lower [Mg/Fe] values and higher [Fe/H]. Despite being continuous, these distributions are bimodal in most cases. The overlap in [Fe/H] is small, and different [Mg/Fe] components show up as peaks instead of sequences (even when the latter are present for individual particles). The larger the spatial bins, the narrower the [Mg/Fe]–[Fe/H] distribution. This narrowing helps amplify the density of different [Mg/Fe] peaks, often leading to a clearer bimodality in mock IFS observations than for original star particles. We also assessed the correspondence of chemical bimodalities with the distinction between geometric thick and thin disks. Their individual particles have different distributions, but mostly overlap in [Mg/Fe] and [Fe/H]. However, integrated properties of geometric thick and thin disks in mock maps do mostly segregate into different regions of the [Mg/Fe]–[Fe/H] plane. In bimodal distributions, they correspond to the two distinct peaks. Our results show that this approach can be used for bimodality studies in future IFS observations of edge-on external galaxies. [ABSTRACT FROM AUTHOR]

We present a chemical analysis of selected H II regions from the PHANGS-MUSE nebular catalogue. Our intent is to empirically re-calibrate strong-line diagnostics of gas-phase metallicity, applicable across a wide range of metallicities within nearby star-forming galaxies. To ensure reliable measurements of auroral line fluxes, we carried out a new spectral fitting procedure whereby only restricted wavelength regions around the emission lines of interest are taken into account: this assures a better fit for the stellar continuum. No prior cuts to nebulae luminosity were applied to limit biases in auroral line detections. Ionic abundances of O+, O2+, N+, S+, and S2+ were estimated by applying the direct method. We integrated the selected PHANGS-MUSE sample with other existing auroral line catalogues, appropriately re-analysed to obtain a homogeneous dataset. This was used to derive strong-line diagnostic calibrations that span from 12 + log(O/H) = 7.5 to 8.8. We investigate their dependence on the ionisation parameter and conclude that it is likely the primary cause of the significant scatter observed in these diagnostics. We apply our newly calibrated strong-line diagnostics to the total sample of H II regions from the PHANGS-MUSE nebular catalogue, and we exploit these indirect metallicity estimates to study the radial metallicity gradient within each of the 19 galaxies of the sample. We compare our results with the literature and find good agreement, validating our procedure and findings. With this paper, we release the full catalogue of auroral and nebular line fluxes for the selected H II regions from the PHANGS-MUSE nebular catalogue. This is the first catalogue of direct chemical abundance measurements carried out with PHANGS-MUSE data. [ABSTRACT FROM AUTHOR]

The study of gas-phase metallicity and its spatial distribution at high redshift is crucial to understand the processes that shaped the growth and evolution of galaxies in the early Universe. Here we study the spatially resolved metallicity in three systems at z ∼ 6 − 8, namely A2744-YD4, BDF-3299, and COSMOS24108, with JWST NIRSpec IFU low-resolution (R ∼ 100) spectroscopic observations. These are among the highest-z sources in which metallicity gradients have been probed so far. Each of these systems hosts several spatial components in the process of merging within a few kiloparsecs, identified from the rest-frame UV and optical stellar continuum and ionised gas emission line maps. The sources have heterogeneous properties, with stellar masses log(M*/M⊙) ∼7.6–9.3, star formation rates (SFRs) ∼1–15 M⊙ yr−1, and gas-phase metallicities 12+log(O/H) ∼7.7–8.3, which exhibit a large scatter within each system. Their properties are generally consistent with those of the highest-redshift samples to date (z ∼ 3 − 10), though the sources in A2744-YD4 and COSMOS24108 are at the high end of the mass-metallicity relation (MZR) defined by the z ∼ 3 − 10 sources. Moreover, the targets in this work follow the predicted slope of the MZR at z ∼ 6 − 8 from most cosmological simulations. The gas-phase metallicity gradients are consistent with being flat in the main sources of each system. Flat metallicity gradients are thought to arise from gas mixing processes on galaxy scales, such as mergers or galactic outflows and supernova winds driven by intense stellar feedback, which wash out any gradient formed in the galaxy. The existence of flat gradients at z ∼ 6 − 8 sets also important constraints on future cosmological simulations and chemical evolution models, whose predictions on the cosmic evolution of metallicity gradients often differ significantly, especially at high redshift, but are mostly limited to z ≲ 3 so far. [ABSTRACT FROM AUTHOR]

Self-enrichment is one of the leading explanations for chemical anomalies in globular clusters. In this scenario, various candidate polluter stars have been proposed to eject gas with altered chemical composition during the self-enrichment process. Most of the proposed polluters will also eject radioactive |$^{26}$| Al into the surroundings. Hence, any detection of |$^{26}$| Al in young massive star clusters (YMCs) would support the self-enrichment scenario if YMCs were indeed the progenitors of globular clusters. Observations of gamma-ray data from COMPTEL and INTEGRAL, as well as detections of |$^{26}$| AlF molecules by the Atacama Large Millimeter-submillimeter Array (ALMA), indicate the maturing of |$^{26}$| Al detection methods. Detection possibilities will be enhanced in the short- to mid-term by the upcoming launch of the Compton Spectrometer and Imager (COSI). The Square Kilometre Array (SKA) could in principle also detect radio recombination lines of the positronium formed from the decay products of |$^{26}$| Al. Here, we show for a sample of YMCs in the nearby Universe, where self-enrichment could plausibly take place. For some nearby galaxies, this could enhance |$^{26}$| Al by an order of one magnitude. Detecting |$^{26}$| AlF with ALMA appears feasible for many candidate self-enrichment clusters, although significant challenges remain with other detection methods. The Large Magellanic Cloud, with its YMC R136, stands out as the most promising candidate. Detecting a 1.8 MeV radioactive decay line of |$^{26}$| Al here would require at least 15 months of targeted observation with COSI, assuming ongoing self-enrichment in R136. [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]

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]

Recent observations of high-redshift galaxies have revealed starburst galaxies with excessive amounts of nitrogen, well above that expected in standard evolutionary models. The Sunburst Arc galaxy, particularly its young and massive star cluster, represents the closest (⁠|$z=2.4$|⁠) and brightest of these as a strongly lensed object. In this work, we study the chemical history of this star cluster to determine the origin of the elevated gas-phase nitrogen using a chemical evolution model. Our model includes the enrichment of OB stars through stellar winds and core-collapse supernovae assuming that massive stars (⁠|$M\gt 25$|   |$\mathrm{ M}_\odot$|⁠) collapse directly into black holes at the end of their lives. We fit the model parameters to the observed chemical abundances of the Sunburst Arc cluster: O/H, C/O, and N/O. We find that the observed chemical abundances can be explained by models featuring intense star formation events, characterized by rapid gas accretion and high star formation efficiencies. Additionally, the stellar population contributing to the gas enrichment must exclude Wolf–Rayet stars. These conditions might be present in other nitrogen-rich objects as their similar chemical abundances suggest a common history. As previous studies have proposed the presence of Wolf–Rayet stars in the new nitrogen-rich objects, further research using chemodynamic modeling is necessary to ascertain the true nature of these objects. [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]

One of the most important questions in astrophysics is what causes galaxies to stop forming stars. Previous studies have shown a tight link between quiescence and black hole mass. Other studies have revealed that quiescence is also associated with 'starvation', the halting of gas inflows, which results in the remaining gas being used up by star formation and in rapid chemical enrichment. In this work, we find the missing link between these two findings. Using a large sample of galaxies, we uncover the intrinsic dependences of the stellar metallicity on galaxy properties. In the case of star-forming galaxies, stellar metallicity is primarily driven by stellar mass. However, for passive galaxies, the stellar metallicity is primarily driven by the stellar velocity dispersion. The latter is known to be tightly correlated with black hole mass. This result can be seen as connecting previous studies, where the integrated effect of black hole feedback (i.e. black hole mass, traced by the velocity dispersion) prevents gas inflows, starving the galaxy, which is seen by the rapid increase in the stellar metallicity, and leading to the galaxy becoming passive. [ABSTRACT FROM AUTHOR]

Chemical evolution models predict a gradual build-up of 13C in the Universe, based on empirical nuclear reaction rates and assumptions on the properties of stellar populations. However, old metal-poor stars within the Galaxy contain more 13C than is predicted, suggesting that further refinements to the models are necessary. Gas at high-redshift provides important supplementary information at metallicities |$-2\lesssim \left[{\rm Fe/H}\right]\lesssim -1$|⁠ , for which there are only a few measurements in the Galaxy. We obtained new, high-quality, VLT/ESPRESSO observations of the QSO B1331 |$+$| 170 and used them to measure 12C/13C in the damped Lyman- |$\alpha$| system (DLA) at |$z_{\rm abs}=1.776$|⁠ , with |$\left[{\rm Fe/H}\right]$| = −1.27. ai-vpfit , an artificial intelligence tool based on genetic algorithms and guided by a spectroscopic information criterion, was used to explore different possible kinematic structures of the carbon gas. Three hundred independent ai-vpfit models of the absorption system were produced using pre-set 12C/13C values, ranging from 4 to 500. Our results show that |${\rm ^{12}C / ^{13}C}=28.5^{+51.5}_{-10.4}$|⁠ , suggesting a possibility of 13C production at low metallicity. [ABSTRACT FROM AUTHOR]

We report a significantly tighter trend between gaseous N/O and |$M_*/R_\mathrm{ e}$| (a proxy for gravitational potential) than has previously been reported between gaseous metallicity and |$M_*/R_\mathrm{ e}$|⁠ , for star-forming galaxies in the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey. We argue this result to be a consequence of deeper potential wells conferring greater resistance to metal outflows while also being associated with earlier star-formation histories, combined with N/O being comparatively unaffected by metal-poor inflows. The potential–N/O relation thus appears to be both more resistant to short time-scale baryonic processes and also more reflective of a galaxy's chemical evolution state, when compared to previously considered relations. [ABSTRACT FROM AUTHOR]

Pair-instability supernovae (PISNe) have long been predicted to be the final fates of near-zero-metallicity very massive stars (⁠|$Z \lt Z_\odot /3$|⁠ , M |$_\mathrm{ZAMS} \gtrsim 140\, \text{M}_\odot$|⁠). However, no definite PISN has been observed to date, leaving theoretical modelling validation open. To investigate the observability of these explosive transients, we combine detailed stellar evolution models for PISNe formation, computed from the binary population and spectral synthesis code suite, bpass , with the star formation history of all individual computational elements in the Illustris-TNG simulation. This allows us to compute comic PISN rates and predict their host galaxy properties. Of particular importance is that IllustrisTNG galaxies do not have uniform metallicities throughout, with metal-enriched galaxies often harbouring metal-poor pockets of gas where PISN progenitors may form. Accounting for the chemical inhomogeneities within these galaxies, we find that the peak redshift of PISNe formation is |$z=3.5$| instead of the value of |$z=6$| when ignoring chemical inhomogeneities within galaxies. Furthermore, the rate increases by an order of magnitude from 1.9 to 29 PISN Gpc |$^{-3}$| yr |$^{-1}$| at |$z=0$|⁠ , if the chemical inhomogeneities are considered. Using state-of-the-art theoretical PISN light curves, we find an observed rate of 13.8 (1.2) visible PISNe per year for the Euclid-Deep survey, or 83 (7.3) over the 6-yr lifetime of the mission when considering chemically inhomogeneous (homogenous) systems. Interestingly, only 12 per cent of helium PISN progenitors are sufficiently massive to power a superluminous supernova event, which can potentially explain why PISN identification in time-domain surveys remains elusive and progress requires dedicated strategies. [ABSTRACT FROM AUTHOR]

Context. Accurate mock halo catalogues are indispensable data products for developing and validating cosmological inference pipelines. A major challenge in generating mock catalogues is modelling the halo or galaxy bias, which is the mapping from matter density to dark matter halos or observable galaxies. To this end, N-body codes produce state-of-the-art catalogues. However, generating large numbers of these N-body simulations for big volumes, especially if magnetohydrodynamics are included, requires significant computational time. Aims. We introduce and benchmark a differentiable and physics-informed neural network that can generate mock halo catalogues of comparable quality to those obtained from full N-body codes. The model design is computationally efficient for the training procedure and the production of large mock catalogue suites. Methods. We present a neural network, relying only on 18 to 34 trainable parameters, that produces halo catalogues from dark matter overdensity fields. The reduction in network weights was realised through incorporating symmetries motivated by first principles into our model architecture. We trained our model using dark-matter-only N-body simulations across different resolutions, redshifts, and mass bins. We validated the final mock catalogues by comparing them to N-body halo catalogues using different N-point correlation functions. Results. Our model produces mock halo catalogues consistent with the reference simulations, showing that this novel network is a promising way to generate mock data for upcoming wide-field surveys due to its computational efficiency. Moreover, we find that the network can be trained on approximate overdensity fields to reduce the computational cost further. We also present how the trained network parameters can be interpreted to give insights into the physics of structure formation. Finally, we discuss the current limitations of our model as well as more general requirements and pitfalls of approximate halo mock generation that became evident from this study. [ABSTRACT FROM AUTHOR]

We aim to constrain the chemo-dynamical properties of the Sagittarius (Sgr) dwarf galaxy using carbon abundances. At low metal- licities in particular, these properties reveal the early chemical evolution of a system, tracing the contributing supernovae (SNe) and how much of their ejecta eventually made it into the next stellar generation. Our sample from the Pristine Inner Galaxy Survey (PIGS) includes ~350 metal-poor ([Fe/H] < −1.5) stars in the main body of Sgr with good quality spectroscopic observations. Our metal-poor Sgr population has a larger velocity dispersion than metal-rich Sgr from the literature, which could be explained by outside-in star formation, extreme Galactic tidal perturbations, and/or the presence of a metal-rich disc and bar + metal-poor halo. The average carbon abundance [C/Fe] in Sgr is similar to that of other classical dwarf galaxies (DGs) and consistently lower than in the Milky Way by ~0.2–0.3 dex at low metallicities. The interstellar medium in DGs, including Sgr, may have retained yields from more energetic Population III and II supernovae (SNe), thereby reducing the average [C/Fe]. Additionally, SNe Ia producing more Fe than C would start to contribute at lower metallicity in DGs/Sgr than in the Galaxy. The presence of a [C/Fe] gradient for Sgr stars with [Fe/H] ≳ −2.0 (~6.8 × 10−4 dex arcmin−1) suggests that SNe la contributed to the system at those metallicities, especially in its inner regions. There is a low frequency of carbon-enhanced metal-poor (CEMP) stars in our Sgr sample. At higher metallicities and carbon abundances (i.e. mostly CEMPs), this may be due to photometric selection effects, but those are less likely to affect non-CEMP stars. Given the lower average [C/Fe] in DGs, we propose using the same CEMP definition ([C/Fe] > +0.7) as that applied to the Galaxy at large ends up underpredicting the number of CEMP stars in DGs. Burthermore, for Sgr, a cut at [C/Fe] ∽ +0.35 may be more appropriate, which brings the frequency of CEMP stars in agreement with that of the whole Galaxy. [ABSTRACT FROM AUTHOR]

Context. In stars, metallicity is usually traced using Fe, while in nebulae, O serves as the preferred proxy. Both elements have different nucleosynthetic origins and are not directly comparable. Additionally, in ionized nebulae, Fe is heavily depleted onto dust grains. Aims. We investigate the distribution of Fe gas abundances in a sample of 452 star-forming nebulae with [Fe III] λ4658 detections and their relationship with O and N abundances. Additionally, we analyze the depletion of Fe onto dust grains in photoionized environments. Methods. We homogeneously determined the chemical abundances with direct determinations of electron temperature (Te), considering the effect of possible internal variations of this parameter. We adopted a sample of 300 Galactic stars to interpret the nebular findings. Results. We find a moderate linear correlation (r = −0.59) between Fe/O and O/H. In turn, we report a stronger correlation (r = −0.80) between Fe/N and N/H. We interpret the tighter correlation as evidence that Fe and N are produced on similar timescales while Fe- dust depletion scales with the Fe availability. The apparently flat distribution between Fe/N and N/H in Milky Way stars supports this interpretation. We find that when 12+log(O/H)<7.6, the nebulae seem to reach a plateau value around log(Fe/O) ≈ −1.7. If this trend were confirmed, it would be consistent with a very small amount of Fe dust in these systems, similar to what is observed in high-z galaxies discovered by the James Webb Space Telescope (JWST). We derive a relationship that allows us to approximate the fraction of Fe trapped into dust in ionized nebulae. If the O-dust scales in the same way, its possible contribution in low-metallicity nebulae would be negligible. After analyzing the Fe/O abundances in J0811+4730 and J1631+4426, we do not see evidence of the presence of very massive stars with Minit > 300 M⊙ in these systems. Conclusions. The close relation observed between the N and Fe abundances has the potential to serve as a link between stellar and nebular chemical studies. This requires an expansion of the number of abundance determinations for these elements in both stars and star-forming nebulae, especially at low metallicities. [ABSTRACT FROM AUTHOR]

We quantified the disparity between gas-phase and stellar metallicity in a large galaxy sample obtained from the MaNGA DR17 survey. We found that the gas metallicity is on average closely aligned with the stellar metallicity in the centers of intermediate-mass galaxies. Conversely, the difference is notably larger within the center of massive galaxies. It reaches about −0.18 dex on average for the most massive galaxies, while for low-mass galaxies, the gas metallicity exhibits a slightly lower value than the stellar metallicity. Moreover, the most prominent instances of a reduced gas-phase metallicity in relation to stellar metallicity were observed within the centers of massive red galaxies with low specific star formation rates. Because of the absence of a correlation between the integral mass fraction of neutral gas and the disparity between gas and stellar metallicity, we suggest that the diminished gas-phase metallicity in the centers of massive galaxies might be attributed to the replenishment of gas-depleted central regions through processes such as radial gas flows or accretion from the circumgalactic medium rather than gas infall from the intergalactic medium. [ABSTRACT FROM AUTHOR]

We present a search for galaxies in the local Universe with extremely low oxygen abundance, that is, more than 25 times lower than solar, which corresponds to 12 + log(O/H) < 7.3. To determine the oxygen abundance, we apply the direct Te method for objects where the [O III]λ4363 line is detected. We identified 21 extremely metal-poor galaxies in the early data release of the Dark Energy Spectroscopic Instrument (DESI EDR), for some of which we also derived N/O, Ne/O, Ar/O, and S/O ratios. We find that many DESI galaxies with extremely low oxygen abundance exhibit a higher N/O ratio in comparison to the reference low-metallicity sample collected from the literature. We suggest that the elevation in N/O ratio may be explained by a contamination with metal-rich gas caused by gas inflow or a merger event. Moreover, contrary to some recent studies, we find that Ar/O and S/O ratios are enhanced as well, while the Ne/O ratio does not show such elevation. One of the galaxies, J0713+5608, has a remarkably low oxygen abundance of 6.978 ± 0.095 dex. This measurement aligns with the lowest known oxygen abundances in galaxies to date. Given the relatively high uncertainty, this galaxy may have the lowest oxygen abundance ever found. Additionally, J0713+5608 exhibited an enhanced N/O ratio compared to the typical N/O ratio observed in metal-poor galaxies within the local Universe. [ABSTRACT FROM AUTHOR]

Context. Giant (> 100 kpc) nebulae associated with active galaxies provide rich information about the circumgalactic medium around galaxies, its link with the interstellar medium of the hosts, and the mechanisms involved in their evolution. Aims. We have studied the giant nebula associated with the Teacup (z = 0.085) quasar based on VLT MUSE integral field spectroscopy to investigate whether the well-known giant (∼10 kpc) active galactic nucleus (AGN) -induced outflow has an impact on the distribution of heavy elements in and outside the host galaxy. Methods. We have mapped the oxygen and nitrogen gas relative abundances (O/H and N/O) in two spatial dimensions across the giant nebula and within the galaxy by means of comparing emission line ratios with photoionisation model predictions. Results. The widely studied AGN-driven outflow responsible for the ∼10 kpc ionised bubble is enhancing the gas metal abundance up to ∼10 kpc from the AGN. O/H is solar or slightly higher at the edges of the bubble, in comparison with the subsolar abundances across the rest of the nebula median (O/H ∼0.63 (O/H)⊙). Conclusions. AGN feedback can produce metal enrichment at large extranuclear distances in galaxies (≥10 kpc). [ABSTRACT FROM AUTHOR]

Aims. The line of sight toward Sk 143 (AzV 456), an O9.5 Ib star in the Small Magellanic Cloud (SMC), shows significant absorption from neutral atoms and molecules. We report a new study of this line of sight by means of high-resolution spectra obtained with the ESPRESSO spectrograph at the VLT of ESO. Methods. The absorption from neutral and ionized species is well characterized by a single component at vhel ≈ +132 km s−1 that was modeled with the ASTROCOOK code. Results. The rubidium Rb I 780.0 nm line is detected for the first time outside the Galaxy, and we derive [Rb/H] = −1.86 ± 0.09. As a result of the high resolution, the 85Rb and 87Rb isotope lines are also exceptionally well resolved. The 85Rb/87Rb isotope ratio is 0.46, which is opposite of the meteoritic value of 2.43. This implies that Rb is made through a dominant contribution of the r-process, which is dominant for the 87Rb isotope. We also confirm the presence of 7Li I 670.7 nm and set a limit on the isotopic ratio of 6Li/7Li < 0.1. Conclusions. The dominance of the 87Rb isotope implies that Rb is made through a dominant contribution of the r-process. At the low metallicity of the cloud of [Zn/H] = −1.28 ± 0.09, neutron rich material may have occurred in rotating metal-poor massive stars. Moreover, the low metallicity of the cloud leads to an absolute Li abundance of A(7Li) ≈ 2.2, which differs from the expectation from big bang nucleosynthesis. Because the gas-phase abundance is not affected by stellar depletion, the burning of Li inside the halo stars is probably not the solution for the cosmological 7Li problem. [ABSTRACT FROM AUTHOR]

We investigated the stellar mass-metallicity relation (MZR) using a sample of 637 quiescent galaxies with 10.4 ≤ log(M*/M⊙) < 11.7 selected from the LEGA-C survey at 0.6 ≤ z ≤ 1. We derived mass-weighted stellar metallicities using full-spectral fitting. We find that while lower-mass galaxies are both metal-rich and metal-poor, there are no metal-poor galaxies at high masses, and that metallicity is bounded at low values by a mass-dependent lower limit. This lower limit increases with mass, empirically defining a MEtallicity-Mass Exclusion (MEME) zone. We find that the spectral index MgFe ≡ √Mgb × Fe4383, a proxy for the stellar metallicity, also shows a mass-dependent lower limit resembling the MEME relation. Crucially, MgFe is independent of stellar population models and fitting methods. By constructing the metallicity enrichment histories, we find that, after the first gigayear, the star formation history of galaxies has a mild impact on the observed metallicity distribution. Finally, from the average formation times, we find that galaxies populate differently the metallicity-mass plane at different cosmic times, and that the MEME limit is recovered by galaxies that formed at z ≥ 3. Our work suggests that the stellar metallicity of quiescent galaxies is bounded by a lower limit which increases with the stellar mass. On the other hand, low-mass galaxies can have metallicities as high as galaxies ∼1 dex more massive. This suggests that, at log(M*/M⊙)≥10.4, rather than lower-mass galaxies being systematically less metallic, the observed MZR might be a consequence of the lack of massive metal-poor galaxies. [ABSTRACT FROM AUTHOR]

Context. Gamma-ray bursts are the most energetic known explosions. Although they fade rapidly, they give us the opportunity to measure redshift and important properties of their host galaxies. We report the photometric and spectroscopic study of the Swift GRB 160203A at z = 3.518, and its host galaxy. Fine-structure absorption lines, detected in the afterglow at different epochs, allow us to investigate variability due to the strong fading background source. Aims. We obtained two optical to near-infrared spectra of the GRB afterglow with X-shooter on ESO/VLT, 18 minutes and 5.7 hours after the burst, allowing us to investigate temporal changes of fine-structure absorption lines. Methods. We measured H I column density log N(HI/cm–2) = 21.75 ± 0.10, and several heavy-element ions along the GRB sightline in the host galaxy, among which Si II, Al II, Al III, C II, Ni II, Si IV, C IV, Zn II and Fe II, and Fe II∗ and Si II∗ fine-structure transitions from energetic levels excited by the afterglow, at the common redshift z = 3.518. We measured [M/H]TOT = –0.78 ± 0.13 and a [Zn/Fe]FIT = 0.69 ± 0.15, representing the total (dust corrected) metallicity and dust depletion, respectively. We detected additional intervening systems along the line of sight at ɀ = 1.03, ɀ = 1.26, ɀ = 1.98, ɀ = 1.99, ɀ = 2.20, and ɀ = 2.83. We could not measure significant variability in the strength of the fine-structure lines throughout all the observations and determined an upper limit for the GRB distance from the absorber of d < 300 pc, adopting the canonical UV pumping scenario. However, we note that the quality of our data is not sufficient to conclusively rule out collisions as an alternative mechanism. Results. GRB 160203A belongs to a growing sample of GRBs with medium resolution spectroscopy, provided by the Swift/X-shooter legacy programme, which enables a detailed investigation of the interstellar medium in high-redshift GRB host galaxies. In particular, this host galaxy shows relatively high metal enrichment and dust depletion already in place when the universe was only 1.8 Gyr old. [ABSTRACT FROM AUTHOR]

We present JWST/NIRSpec integral-field spectroscopy observations of the z |$\sim$| 9.11 lensed galaxy MACS1149-JD1, as part of the GA-NIFS programme. The data were obtained with both the G395H grating (R |$\sim$| 2700) and the prism (R |$\sim$| 100). This target shows a main elongated UV-bright clump and a secondary component detected in continuum emission at a projected distance of 2 kpc. The R2700 data trace the ionized-gas morpho-kinematics in between the two components, showing an elongated emission mainly traced by [O  iii ]  |$\lambda$| 5007. We spatially resolve [O  ii ]  |$\lambda \lambda $| 3726,3729, [O  iii ]  |$\lambda \lambda$| 4959,5007, and [O  iii ]  |$\lambda$| 4363, which enable us to map the electron density (n |$_{\rm e} \sim 1.0 \times 10^3$|  cm |$^{-3}$|⁠), temperature (T |$_{\rm e} \sim 1.6 \times 10^4$|  K), and direct-method gas-phase metallicity (−1.2 to −0.7 dex solar). A spatially resolved full-spectrum modelling of the prism indicates a north-south gas metallicity and stellar age gradient between the two components. We found 3 |$\sigma$| evidence of a spatially resolved anticorrelation of the gas-phase metallicity and the star formation rate density, which is likely driven by gas inflows, enhancing the star formation in JD1. We employ high-z sensitive diagnostic diagrams to rule out the presence of a strong AGN in the main component. These findings show the unambiguous presence of two distinct stellar populations, with the majority of the mass ascribed to an old star formation burst, as suggested by previous works. We disfavour the possibility of a rotating-disc nature for MACS1149-JD1; we favour a merger event that has led to a recent burst of star formation in two separate regions, as supported by high values of [O  iii ]  |$\lambda$| 5007/ |$\mathrm{H}\,\beta$|⁠ , ionized gas velocity dispersion, and gas-phase metallicity. [ABSTRACT FROM AUTHOR]

Combining the public JWST /NIRCam imaging programs CEERS, PRIMER, and JADES, spanning a total area of |$\sim 500\, {\rm arcmin}^2$|⁠ , we obtain a sample of |$\gt $| 30 000 galaxies at |$z_{\rm phot}\sim 4\!-\!9$| that allows us to perform a complete, rest-optical-selected census of the galaxy population at |$z\gt 3$|⁠. Comparing the stellar mass |$M_*$| and the UV-slope |$\beta$| distributions between JWST - and HST -selected samples, we generally find very good agreement and no significant biases. Nevertheless, JWST enables us to probe a new population of UV-red galaxies that was missing from previous HST -based Lyman-break galaxy (LBG) samples. We measure galaxy stellar mass functions (SMFs) at |$z\sim 4\!-\!9$| down to limiting masses of |$10^{7.5}\!-\!10^{8.5}\, {\rm M_\odot }$|⁠ , finding steep low-mass slopes over the entire redshift range, reaching values of |$\alpha \approx -2$| at |$z\gtrsim 6$|⁠. At the high-mass end, UV-red galaxies dominate at least out to |$z\sim 6$|⁠. The implied redshift evolution of the SMF suggests a rapid build-up of massive dust-obscured or quiescent galaxies from |$z\sim 6$| to |$z\sim 4$| as well as an enhanced efficiency of star formation towards earlier times (⁠|$z\gtrsim 6$|⁠). Finally, we show that the galaxy mass density grows by a factor |$\sim 20\times$| from |$z\sim 9$| to |$z\sim 4$|⁠. Our results emphasize the importance of rest-frame optically selected samples in inferring accurate distributions of physical properties and studying the mass build-up of galaxies in the first 1.5 Gyr of cosmic history. [ABSTRACT FROM AUTHOR]

For the first time, a calibration between the He  i |$\lambda 5876$| /H  |$\beta$| emission line ratio and the helium abundance y = 12 + log(He/H) for Narrow line regions of Seyfert 2 Active Galactic Nuclei is proposed. In this context, observational data (taken from the SDSS-DR15 and from the literature) and direct abundance estimates (via the |$T_{\rm e}$| -method) for a sample of 65 local (⁠|$z \: \lt \: 0.2$|⁠) Seyfert 2 nuclei are considered. The resulting calibration estimates the y abundance with an average uncertainty of 0.02 dex. Applying our calibration to spectroscopic data containing only strong emission lines, it yields a helium abundance distribution similar to that obtained via the |$T_{\rm e}$| -method. Some cautions must be considered to apply our calibration for Seyfert 2 nuclei with high values of electron temperature (⁠|${\gtrsim} 20\, 000$|  K) or ionization parameter (⁠|$\log U \ \gt\ {-}2.0$|⁠). [ABSTRACT FROM AUTHOR]

In this study, we explore the impact of the galactic interaction/mergers on the central oxygen abundance. We analyse 234 star-forming galaxies included in the Calar Alto Legacy Integral Field Area survey with integrated molecular gas observations from the Atacama Pathfinder EXperiment millimeter telescope and the CARMA interferometer. This database has the most optical integral field spectroscopy data with CO data for yet, with integrated measurements within |$\sim 1~{R_{\rm{eff}}}$|⁠. Our sample includes 125 isolated galaxies (control sample) and 109 galaxies in different merging stages. We find that despite whether the merging galaxies show an increase or decrease in their molecular gas fraction, the oxygen abundance does not vary significantly, in comparison to our control sample. Therefore, the enhancement and suppression of oxygen abundance are similar in both isolated galaxies and interacting/merging galaxies. On the contrary, regardless of the merger stage (including isolated sample), galaxies that present an increase in their specific star formation rate present a metallicity dilution. We suggest that both internal and external events affect the chemical composition of merging galaxies. [ABSTRACT FROM AUTHOR]

The analysis of the cosmic microwave background data acquired by the Atacama Cosmology Telescope and the large-scale (⁠|$\ell \lesssim 1300$|⁠) Planck Telescope show a preference for the early dark energy (EDE) theory, which was set to alleviate the Hubble tension of the |$\Lambda$| cold dark matter (⁠|$\Lambda$| CDM) model by decreasing the sound horizon |$r_{s}$|⁠ , and gives |$H_{0} \approx 72$| km s |$^{-1}$| Mpc |$^{-1}$|⁠. However, the EDE model is commonly questioned for exacerbating the |$\sigma _8$| tension on top of the |$\Lambda$| CDM model, and its lack of preference from the late-time matter power spectrum observations, e.g. Baryon Oscillation Spectroscopic Survey. In light of the current obscurities, we inspect if the high redshift galaxy abundance, i.e. stellar mass function/density and luminosity function, can independently probe the EDE model. Our result shows that, compared to |$\Lambda$| CDM, the EDE model prediction at |$z\gt 10$| displays better consistency with the unexpectedly high results observed by the JWST. At lower redshift, the EDE model only fits the most luminous/massive end, with the majority of the data presenting better consistency with |$\Lambda$| CDM, implying that adding an extra luminosity/mass-sensitive suppression mechanism of the galaxy formation is required for EDE to explain all data around |$z\sim 7-10$|⁠. [ABSTRACT FROM AUTHOR]

The 21-cm spectral line widths, |$w_{50}$|⁠ , of galaxies are an approximate tracer of their dynamical masses, such that the dark matter halo mass function is imprinted in the number density of galaxies as a function of |$w_{50}$|⁠. Correcting observed number counts for survey incompleteness at the level of accuracy needed to place competitive constraints on warm dark matter (WDM) cosmological models is very challenging, but forward-modelling the results of cosmological hydrodynamical galaxy formation simulations into observational data space is more straightforward. We take this approach to make predictions for an ALFALFA-like survey from simulations using the EAGLE galaxy formation model in both cold (CDM) and WDM cosmogonies. We find that for WDM cosmogonies more galaxies are detected at the low- |$w_{50}$| end of the 21-cm velocity width function than in the CDM cosmogony, contrary to what might naïvely be expected from the suppression of power on small scales in such models. This is because low-mass galaxies form later and retain more gas in WDM cosmogonies (with EAGLE). While some shortcomings in the treatment of cold gas in the EAGLE model preclude placing definitive constraints on WDM scenarios, our analysis illustrates that near-future simulations with more accurate modelling of cold gas will likely make strong constraints possible, especially in conjunction with new 21-cm surveys such as WALLABY. [ABSTRACT FROM AUTHOR]

This document is a correction to a previous article on gas-phase metallicities in MaNGA. The correction addresses an error in the calculation of O3N2-based calibrations, resulting in incorrect metallicity values. The correction decreases the raw metallicity values for these calibrations and slightly increases the number of overall spaxels with metallicities. The document also includes additional tables showing the number of metallicity values per calibration and the scatter of emission-line permutations between calibrations. The update on the polynomial fits used in the study shows a shift in the fits when converting between different calibrations, with a median magnitude of 0.032 dex. Some figures in the original study are affected, but most are not visibly different. The emission-line data used in the study is publicly available, and metallicity values can be obtained upon request. [Extracted from the article]

We examine the stellar [ |$\alpha$| /Fe]–[Fe/H] distribution of |$\simeq 1000$| present-day galaxies in a high-resolution EAGLE simulation. Roughly half of the galaxies exhibit the canonical distribution, characterized by a sequence of low-metallicity stars with high [ |$\alpha$| /Fe] that transitions at a 'knee' to a sequence of declining [ |$\alpha$| /Fe] with increasing metallicity. This population yields a knee metallicity–galaxy–mass relation similar to that observed in Local Group galaxies, both in slope and scatter. However, many simulated galaxies lack a knee or exhibit more complicated distributions. Knees are found only in galaxies with star formation histories (SFHs) featuring a sustained decline from an early peak (⁠|$t\simeq 7~{\rm Gyr}$|⁠), which enables enrichment by Type Ia supernovae to dominate that due to Type II supernovae (SN II), reducing [ |$\alpha$| /Fe] in the interstellar gas. The simulation thus indicates that, contrary to the common interpretation implied by analytic galactic chemical evolution (GCE) models, knee formation is not a consequence of the onset of enrichment by SN Ia. We use the SFH of a simulated galaxy exhibiting a knee as input to the vice GCE model, finding it yields an |$\alpha$| -rich plateau enriched only by SN II, but the plateau comprises little stellar mass and the galaxy forms few metal-poor ([Fe/H] |$\lesssim$| |$-$| 1) stars. This follows from the short constant gas consumption time-scale typically assumed by GCEs, which implies the presence of a readily enriched low-mass gas reservoir. When an initially longer, evolving consumption time-scale is adopted, vice reproduces the simulated galaxy's track through the [ |$\alpha$| /Fe]–[Fe/H] plane and its metallicity distribution function. [ABSTRACT FROM AUTHOR]

We present spatially resolved, simple stellar population equivalent ages, stellar metallicities, and abundance ratios for 456 massive (⁠|$10.3\lesssim \log (\mathrm{M}_*/\mathrm{M}_\odot)\lesssim 11.8$|⁠) quiescent galaxies at |$0.6\lesssim z\lesssim 1.0$| from the Large Early Galaxy Astrophysics Census, derived using full-spectrum models. Typically, we find flat age and [Mg/Fe] gradients, and negative [Fe/H] gradients, implying iron-rich cores. We also estimate intrinsic [Fe/H] gradients via forward modelling. We examine the observed gradients in three age bins. Younger quiescent galaxies typically have negative [Fe/H] gradients and positive age gradients, possibly indicating a recent central starburst. Additionally, this finding suggests that photometrically measured flat colour gradients in young quiescent galaxies are the result of the positive age and negative metallicity gradients cancelling each other. For older quiescent galaxies, the age gradients become flat and [Fe/H] gradients weaken, though remain negative. Thus, negative colour gradients at older ages are likely driven by metallicity gradients. The diminishing age gradient may result from the starburst fading. Furthermore, the persistence of the [Fe/H] gradients may suggest that the outskirts are simultaneously built up by mergers with lower metallicity satellites. On the other hand, the gradients could be inherited from the star-forming phase, in which case mergers may not be needed to explain our findings. This work illustrates the need for resolved spectroscopy, instead of just photometry, to measure stellar population gradients. Extending these measurements to higher redshift is imperative for understanding how stellar populations in quiescent galaxies are assembled over cosmic time. [ABSTRACT FROM AUTHOR]

We present determinations of the gas-phase and stellar metallicities of a sample of 65 star-forming galaxies at |$z \simeq 3.5$| using rest-frame far-ultraviolet (FUV) spectroscopy from the VANDELS survey in combination with follow-up rest-frame optical spectroscopy from VLT /KMOS and Keck/MOSFIRE. We infer gas-phase oxygen abundances (⁠|$Z_{\mathrm{g}}$|⁠ ; tracing O/H) via strong optical nebular lines and stellar iron abundances (⁠|$Z_{\star }$|⁠ ; tracing Fe/H) from full spectral fitting to the FUV continuum. Our sample spans the stellar mass range |$8.5 \lt \mathrm{log}(M_{\star }/\mathrm{M}_{\odot }) \lt 10.5$| and shows clear evidence for both a stellar and gas-phase mass-metallicity relation (MZR). We find that our O and Fe abundance estimates both exhibit a similar mass-dependence, such that |$\mathrm{Fe/H}\propto M_{\star }^{0.30\pm 0.11}$| and |$\mathrm{O/H}\propto M_{\star }^{0.32\pm 0.09}$|⁠. At fixed |$M_{\star }$| we find that, relative to their solar values, O abundances are systematically larger than Fe abundances (i.e. α-enhancement). We estimate an average enhancement of |$\mathrm{(O/Fe)} = 2.65 \pm 0.16 \times \mathrm{(O/Fe)_\odot }$| which appears to be independent of |$M_{\star }$|⁠. We employ analytic chemical evolution models to place a constraint on the strength of galactic-level outflows via the mass-outflow factor (⁠|$\eta$|⁠). We show that outflow efficiencies that scale as |$\eta \propto M_{\star }^{-0.32}$| can simultaneously explain the functional form of of the stellar and gas-phase MZR, as well as the degree of α-enhancement at fixed Fe/H. Our results add further evidence to support a picture in which α-enhanced abundance ratios are ubiquitous in high-redshift star-forming galaxies, as expected for young systems whose interstellar medium is primarily enriched by core-collapse supernovae. [ABSTRACT FROM AUTHOR]

Red Geysers are galaxies with low-star formation rates and galactic scale ionized outflows likely driven by low-luminosity active galactic nuclei (AGN). We investigated the impact of AGN winds on the oxygen abundance using integral field spectroscopic data from Mapping Nearby Galaxies for Red Geysers, control galaxies (quiescent galaxies without outflows), and AGN hosts within the inner 1.5 kpc radius. Red Geyser galaxies have higher W |$_{80}$| values compared to those of AGN and controls, with 64 per cent showing W |$_{80}\gt 500$|  km s |$^{-1}$| that is indicative of outflow. Only 40 per cent of controls and 31 per cent of AGNs reach this value. We found a small tendency of the oxygen abundance distribution of controls to be biased towards higher values than those of Red Geysers. However, Red Geysers do not show a correlation between H |$\alpha$| width (parametrized by the W |$_{\rm 80}$|⁠) and oxygen abundance, which indicates that AGN winds are not significantly impacting the chemical abundance of the nuclear region of these galaxies. The oxygen abundance distribution mean value for the tree samples is |$\rm 12+log(O/H)\sim$| 8.7 (⁠|$\mathit{Z}\sim \rm Z_{\odot })$|⁠. On the other hand, AGN hosts show a positive correlation between W |$_{80}$| and O/H which could be due to star formation that outflows from the active nuclei could induce; or to the reservoir of gas that makes the nucleus active, and its is also used in the star formation. [ABSTRACT FROM AUTHOR]

We have estimated the mass of metals in the molecular gas in 13 dusty star-forming galaxies at |$z \sim 4$| in which the gas, based on previous observations, lies in a cold rotating disc. We estimated the metal masses using either the submillimetre line or continuum emission from three tracers of the overall metal content – carbon atoms, carbon monoxide molecules, and dust grains – using the first simultaneous calibration of all three tracers. We obtain very similar mass estimates from the different tracers, which are similar to the entire metal content of a present-day massive early-type galaxy. We used the dynamical masses of these galaxies to estimate an upper limit on the mass of the molecular gas in each galaxy, allowing us to estimate a lower limit on the metal abundance of the gas, finding values for many of the galaxies well above the solar value. We show that the high metal masses and metal abundances are what is expected shortly after the formation of a galaxy for a top-heavy IMF. We suggest a scenario for galaxy evolution in which massive galaxies reach a high metal abundance during their formation phase, which is then gradually reduced by dry mergers with lower mass galaxies. We show that the metals in the outflows from high-redshift dusty star-forming galaxies can quantitatively explain the long-standing puzzle that such a large fraction of the metals in galaxy clusters (⁠|$\simeq$| 0.75) is in the intracluster gas rather than in the galaxies themselves. [ABSTRACT FROM AUTHOR]

We study the statistics of dwarf galaxy populations as a function of environment in cold dark matter (CDM) and warm dark matter (WDM; sterile neutrino model mass |$M_{{\rm s}}=7.1~{\rm keV}$|⁠ ; half-mode mass |$M_{{\rm hm}} = 6.3\times 10^8$|   |${\rm M}_\odot$|⁠ ; and thermal relic equivalent mass |$m_{{\rm th}} = 2.8~{\rm keV}$|⁠) cosmogonies, using the Evolution and Assembly of GaLaxies and their Environments (EAGLE) galaxy formation model in two counterpart simulations. We measure the abundance of dwarf galaxies within 3 Mpc of DM haloes with a present-day halo mass similar to the Milky Way, finding that the number of galaxies |$M_{*}\gt 10^7$|   |${\rm M}_\odot$|  is nearly identical for WDM and CDM. However, the cumulative mass function becomes shallower for WDM at lower masses, yielding 50 per cent fewer dwarf galaxies of |$M_{*}\gtrsim 10^{5}$|   |${\rm M}_\odot$|  than CDM. The suppression of low-mass halo counts in WDM increases significantly from high- to low-density regions for haloes in the |$[0.5,2] \times M_ {\rm hm}$| range. The fraction of haloes hosting resolvable galaxies (⁠|$M_*\gtrsim 10^{5}$|   |${\rm M}_\odot$|  ) also diverges from overdense to underdense regions for |$M\gt 2M_ {\rm hm}$|⁠ , as the increased collapse delay at small densities pushes the collapse to after the reionization threshold. However, the stellar mass of WDM haloes at |$[0.5,2]\times M_ {\rm hm}$| is 30 per cent higher per unit halo mass than CDM haloes in underdense regions. We conclude that the suppression of galaxies with |$M_{*}\gtrsim 10^5$|   |${\rm M}_\odot$|  between WDM and CDM is independent of density: the suppression of halo counts and fraction of luminous haloes is balanced by an enhancement in stellar mass–halo mass relation. [ABSTRACT FROM AUTHOR]

Active star formation in dwarf galaxies shapes the morphology of the surrounding nebular environment and ensures the non-uniformity of the chemical elements spatial distribution in it due to the superwind region expansion. Ionizing radiation within the nebular gas produces observed emission lines used for modelling and diagnostics. We introduce a multicomponent photoionization modelling (MPhM) approach that incorporates detailed calculation of diffuse ionizing radiation (DCDIR) based on chemodynamical simulations (ChDSs). Our models aim to replicate crucial emission line intensity ratios within the observed range, employing a thin dense shell between the superwind region and the outer nebular environment to address ChDSs resolution limitations, which render them insensitive to the presence of a superwind shock. MPhM-generated emission line spectra within a small central synthetic aperture and a thin long-slit exhibit excellent agreement with observations, confirming the accuracy of the ionization structure of the nebular environment obtained using the MPhM + DCDIR approach. However, the outward-only approximation fails to reproduce the dwarf galaxies ionization structure. We determined the oxygen abundance using the |$T_e$| - and |$R_{23}$| -methods based on emission lines from MPhM + DCDIR. The resulting abundances align well with values obtained by averaging over the 'observed' volume within synthetic apertures, weighted by mass. The escape fraction of ionizing photons from the dwarf galaxy was found to be larger than that obtained using the outward-only approximation. Employing Kennicutt's calibration corrected for near-UV data, the star formation rate (SFR) was calculated using the |${\rm H}\,\alpha$| luminosity from MPhM + DCDIR. The resulting SFR value is nearly 33 per cent higher than the true one. [ABSTRACT FROM AUTHOR]

It is well known that stars are subject to radial migration, i.e. over time, they move away from their birth location. This dynamical process tends to mix different stellar populations and hence hinders the determination of the true chemical evolution of a galaxy (e.g. metallicity gradients). One way to account for radial migration is to infer stellar birth radii for individual stars. Many attempts to do so have been performed over the last few years, but are limited to the Milky Way, as computing the birth position of stars requires precise measurements of stellar metallicity and age for individual stars that cover large Galactic radii. Fortunately, recent and future surveys will provide numerous opportunities for inferring birth radii for external galaxies such as the LMC. In this paper, we investigate the possibility of doing so using the NIHAO cosmological zoom-in simulations. We find that it is theoretically possible to infer birth radii with a ∼25 per cent median uncertainty for individual stars in galaxies with i) orderliness of the orbits, |$\langle v_\phi \rangle /\sigma _{v} > 2 $|⁠ , ii) a dark matter halo mass greater or equal to approximately the LMC mass (∼2 × 1011  |${\rm M}_\odot$|⁠), and iii) after the average azimuthal velocity of the stellar disc reaches ∼70 per cent of its maximum. From our analysis, we conclude that it is possible and useful to infer birth radii for the LMC and other external galaxies that satisfy the above criteria. [ABSTRACT FROM AUTHOR]

In a hierarchical, dark matter-dominated Universe, stellar mass functions (SMFs), galaxy merger rates, star formation histories (SFHs), satellite abundances, and intracluster light (ICL), should all be intimately connected observables. However, the systematics affecting observations still prevent universal and uniform measurements of, for example, the SMF and the SFHs, inevitably preventing theoretical models to compare with multiple data sets robustly and simultaneously. We here present our holistic semi-empirical model decode (Discrete statistical sEmi-empiriCal mODEl) that converts via abundance matching dark matter merger trees into galaxy assembly histories, using different SMFs in input and predicting all other observables in output in a fully data-driven and self-consistent fashion with minimal assumptions. We find that: (1) weakly evolving or nearly constant SMFs below the knee (⁠|$M_\star \lesssim 10^{11} \, \mathrm{M}_\odot$|⁠) are the best suited to generate SFHs aligned with those inferred from MaNGA, SDSS, GAMA, and, more recently, JWST; (2) the evolution of satellites after infall only affects the satellite abundances and SFHs of massive central galaxies but not their merger histories; (3) the resulting SFR– |$M_\star$| relation is lower in normalization by a factor of |$\sim 2$| with respect to observations, with a flattening at high masses more pronounced in the presence of mergers; (4) the latest data on ICL can be reproduced if mass-loss from mergers is included in the models. Our findings are pivotal in acting as pathfinder to test the self-consistency of the high-quality data from, e.g. JWST and Euclid. [ABSTRACT FROM AUTHOR]

The newly updated GIZMO and Simba based simulation, Simba-C , with its new stellar feedback, chemical enrichment, and recalibrated AGN feedback, allows for a detailed study of the intragroup medium X-ray properties. We discuss the impact of various physical mechanisms, e.g. stellar and AGN feedback, and chemical enrichment, on the composition and the global scaling relations of nearby galaxy groups. We also study the evolution (z = 2 to 0) of the global properties for the |$1\, \mathrm{keV}$| temperature groups. Simba-C shows improved consistent matching with the observations of all X-ray scaling relations compared to Simba. It is well known that AGN feedback has a significant influence on L X, 0.5–2.0– T spec, corr, S 500/2500– T spec, corr, and gas mass fractions, with our Simba-C results consistent with it. Our recalibrated AGN feedback strength also showed an additional improvement in gas entropy, which now aligns with CLoGS observations. The updated stellar feedback and chemical enrichment model is shown to play an important role in our understanding of the chemical abundance ratios and their evolution within galaxy groups. In particular, we find that Simba-C produces an increase in the amount of heavier elements (specifically Si and Fe) relative to O, compared to Simba. [ABSTRACT FROM AUTHOR]

In recent years, the study of the Milky Way has significantly advanced due to extensive spectroscopic surveys of its stars, complemented by astroseismic and astrometric data. However, it remains disjoint from recent advancements in understanding the physics of the Galactic interstellar medium (ISM). This paper introduces a new model for the chemical evolution of the Milky Way that can be constrained on stellar data, because it combines a state-of-the-art ISM model with a Milky Way stellar disc model. Utilizing a data set of red clump stars from APOGEE, known for their precise ages and metallicities, we concentrate on the last 6 billion years – a period marked by Milky Way's secular evolution. We examine the oxygen abundance in the low- |$\alpha$| disc stars relative to their ages and birth radii, validating or constraining critical ISM parameters that remain largely unexplored in extragalactic observations. The models that successfully reproduce the radius–metallicity distribution and the age–metallicity distribution of stars without violating existing ISM observations indicate a need for modest differential oxygen enrichment in Galactic outflows, meaning that the oxygen abundance of outflows is higher than the local ISM abundance, irrespective of outflow mass loading. The models also suggest somewhat elevated ISM gas velocity dispersion levels over the past 6 billion years compared to galaxies of similar mass. The extra turbulence necessary could result from energy from gas accretion onto the Galaxy, supernovae clustering in the ISM, or increased star formation efficiency per freefall time. This work provides a novel approach to constraining the Galactic ISM and outflows, leveraging the detailed insights available from contemporary Milky Way surveys. [ABSTRACT FROM AUTHOR]

Observations of nearby massive galaxies have revealed that they are older and richer in metals and magnesium than their low-mass counterparts. In particular, the overabundance of magnesium compared to iron, [Mg/Fe], is interpreted to reflect the short star formation history that the current massive galaxies underwent early in the Universe. We present a systematic revision of the [Mg/Fe] – velocity dispersion (σ) relation based on stacked spectra of early-type galaxies with a high signal-to-noise ratio from the Sloan Digital Sky Survey. Using the penalized pixel-fitting (pPXF) method and the MILES single stellar population models, we fit a wide optical wavelength range to measure the net α-abundance. The combination of pPXF and α-enhanced MILES models incorrectly leads to an apparently decreasing trend of [α/Fe] with velocity dispersion. We interpret this result as a consequence of variations in the individual abundances of the different α-elements. This warrants caution for a naive use of full spectral fitting algorithms paired with stellar population models that do not take individual elemental abundance variations into account, especially when deriving averaged quantities such as the mean [α/Fe] of a stellar population. In addition, and based on line-strength measurements, we quantify the impact of a non-universal initial mass function on the recovered abundance pattern of galaxies. In particular, we find that a simultaneous fit of the slope of the initial mass function and the [Mg/Fe] results in a shallower [Mg/Fe]–σ relation. Therefore, our results suggest that star formation in massive galaxies lasted longer than what has been reported previously, although it still occurred significantly faster than in the solar neighbourhood. [ABSTRACT FROM AUTHOR]

Edge-on galaxies act as the best laboratories to understand the origin of thin and thick discs in galaxies. Measurement of spatially resolved stellar population properties in such galaxies, particularly age, metallicity, and [α/Fe], are crucial to understanding the formation and evolution of disc galaxies. Such measurements are made possible from stellar population model fits to deep integral field spectroscopic (IFU) observations of resolved galaxies. We utilize archival MUSE IFU observations of the edge-on galaxy ESO 544-27 to uncover the formation history of its thin and thick discs through its stellar populations. We find the thin disc of the galaxy is dominated by an old (>9 Gyr) low [α/Fe] metal-rich stellar population. Its outer thick disc is dominated by an old (>9 Gyr) high [α/Fe] metal-rich component that should have formed with higher star formation efficiency than the Milky Way thick disc. We thus find [α/Fe] dichotomy in ESO 544-27 with its thin and thick discs dominated by low and high [α/Fe] stellar populations, respectively. However, we also find a metal-rich younger (<2 Gyr old) stellar population in ESO 544-27. The galaxy was nearly quenched until its star formation was reignited recently first in the outer and inner thick disc (∼1 Gyr ago) and then in the thin disc (∼600 Myr ago). We thus find that both the low [α/Fe] thin and high [α/Fe] thick discs of ESO 544-27 are inhabited primarily by similarly old metal-rich stellar populations, a contrast to that of other galaxies with known thin and thick disc stellar population properties. [ABSTRACT FROM AUTHOR]

We compare the l-galaxies semi-analytic model to deep observational data from the UKIDSS Ultra Deep Survey (UDS) across the redshift range 0.5 < z < 3. We find that the overabundance of low-mass, passive galaxies at high redshifts in the model can be attributed solely to the properties of 'orphan' galaxies, i.e. satellite galaxies where the simulation has lost track of the host dark matter sub-halo. We implement a simple model that boosts the star formation rates in orphan galaxies by matching them to non-orphaned satellite galaxies at a similar evolutionary stage. This straightforward change largely addresses the discrepancy in the low-mass passive fraction across all redshifts. We find that the orphan problem is somewhat alleviated by higher resolution simulations, but the preservation of a larger gas reservoir in orphans is still required to produce a better fit to the observed space density of low-mass passive galaxies. Our findings are also robust to the precise definition of the passive galaxy population. In general, considering the vastly different prescriptions used for orphans in semi-analytic models, we recommend that they are analysed separately from the resolved satellite galaxy population, particularly with JWST observations reigniting interest in the low-mass regime in which they dominate. [ABSTRACT FROM AUTHOR]

Blue compact galaxies, also known as H  ii galaxies, are dwarf, star-forming objects with relatively simple dynamics, which allows for the investigation of star formation mechanisms in a cleaner manner compared to late-type objects. In this study, we have examined various characteristics of the interstellar medium, in connection with the kinematics and dynamics of ionized gas, in Tol 1004-296 and Tol 0957-278. These two objects were observed using the SOAR Integral Field Spectrometer (SIFS) attached to the Southern Observatory for Astrophysical Research (SOAR). Both galaxies were observed with two gratings: one with medium resolution for monochromatic and abundance maps, and another with high resolution for kinematics and profile analysis. Additionally, we conducted an analysis on the velocity and velocity dispersion maps using intensity–velocity dispersion (I-σ) and velocity–velocity dispersion (Vr-σ) diagrams. Neither object exhibits a rotation pattern, and only Tol 1004-296 shows a velocity gradient between the two principal knots. However, the study reveals the significant role played by velocity dispersion in the star formation process. Specifically, we identified a relationship between monochromatic intensity, metallicity, and velocity dispersion, where high emission corresponds to low metallicity and low velocity dispersion. Tol 1004-296, in particular, exhibits a distinctive linear high velocity dispersion pattern between the two main knots, suggesting that both star formation sites are pushing the gas in opposite directions. [ABSTRACT FROM AUTHOR]

The scatter about the mass-metallicity relation (MZR) has a correlation with the star formation rate (SFR) of galaxies. The lack of evidence of evolution in correlated scatter at z ≲ 2.5 leads many to refer to the relationship between mass, metallicity, and SFR as the Fundamental Metallicity Relation (FMR). Yet, recent high-redshift (z > 3) JWST observations have challenged the fundamental (i.e. redshift-invariant) nature of the FMR. In this work, we show that the cosmological simulations Illustris, IllustrisTNG, and Evolution and Assembly of GaLaxies and their Environment (EAGLE) all predict MZRs that exhibit scatter with a secondary dependence on SFR up to z  = 8. We introduce the concept of a 'strong' FMR, where the strength of correlated scatter does not evolve with time, and a 'weak' FMR, where there is some time evolution. We find that each simulation analysed has a statistically significant weak FMR – there is non-negligible evolution in the strength of the correlation with SFR. Furthermore, we show that the scatter is reduced an additional ∼10–40 per cent at z ≳ 3 when using a weak FMR, compared to assuming a strong FMR. These results highlight the importance of avoiding coarse redshift binning when assessing the FMR. [ABSTRACT FROM AUTHOR]

In this work, we investigated the nitrogen and oxygen abundances in a sample of galaxies with Low Ionization Nuclear Emission Regions (LINERs) in their nucleus. Optical spectroscopic data (3600 – 10 000 Å) of 40 LINERs from the Mapping Nearby Galaxies (MaNGAs) survey were considered. Only objects classified as retired galaxies, that is, whose main ionization sources are post-Asymptotic Giant Branch (pAGB) stars, were selected. The abundance estimates were obtained through detailed photoionization models built with the cloudy code to reproduce a set of observational emission line intensities ratios of the sample. Our results show that LINERs have oxygen and nitrogen abundances in the ranges of |$\rm 8.0 \: \lesssim \: 12+\log (O/H) \: \lesssim \: 9.0$| (mean value 8.74 ± 0.27) and |$\rm 7.6 \: \lesssim \: 12+\log (N/H) \: \lesssim \: 8.5$| (mean value 8.05 ± 0.25), respectively. About 70 per cent of the sample have oversolar O/H and N/H abundances. Our abundance estimates are in consonance with those for Seyfert 2 nuclei and H  ii regions with the highest metallicity, indicating that these distinct object classes show similar enrichment of the interstellar medium (ISM). The LINERs in our sample are located in the higher N/O region of the N/O versus O/H diagram, showing an unexpected negative correlation between these two parameters. These results suggest that these LINERs mainly exhibit a secondary nitrogen production and could be acting some other mechanisms that deviate them from the usual theoretical secondary nitrogen production curve and the H  ii regions observations. However, we did not find any evidence in our data able to support the literature suggested mechanisms. Alternatively, our results show that LINERs do not present any correlation between the N/O abundances and the stellar masses of the hosting galaxies. [ABSTRACT FROM AUTHOR]

We present the results of direct-method metallicity measurements in the disc and outflow of the low-metallicity starburst galaxy NGC 1569. We use Keck Cosmic Web Imager observations to map the galaxy across 54″ (800 pc) along the major axis and 48″ (700 pc) along the minor axis with a spatial resolution of 1″ (∼15 pc). We detect common strong emission lines ([O  iii ] λ5007, H β, [O  ii ] λ3727) and the fainter [O  iii ] λ4363 auroral line, which allows us to measure electron temperature (Te) and metallicity. Theory suggests that outflows drive metals out of the disc driving observed trends between stellar mass and gas-phase metallicity. Our main result is that the metallicity in the outflow is similar to that of the disc, Z out/ Z ISM ≈ 1. This is consistent with previous absorption line studies in higher mass galaxies. Assumption of a mass-loading factor of |$\dot{M}_{\rm out}/{\rm SFR}\sim 3$| makes the metal-loading of NGC 1569 consistent with expectations derived from the mass–metallicity relationship. Our high spatial resolution metallicity maps reveal a region around a supermassive star cluster (SSC-B) with distinctly higher metallicity and higher electron density, compared to the disc. Given the known properties of SSC-B the higher metallicity and density of this region are likely the result of star formation-driven feedback acting on the local scale. Overall, our results are consistent with the picture in which metal-enriched winds pollute the circumgalactic medium surrounding galaxies, and thus connect the small-scale feedback processes to large-scale properties of galaxy haloes. [ABSTRACT FROM AUTHOR]