We use 789 disk-like, star-forming galaxies (with 596 HI detections) from HI follow-up observations for the SDSS-IV MaNGA survey to study the possible role of inner HI gas in causing secondary dependences in the mass-gas-phase metallicity relation. We use the gas-phase metallicity derived at the effective radii of the galaxies. We derive the inner HI mass witHIn the optical radius, but also use the total HI mass and star formation rate (SFR) for a comparison. We confirm the anticorrelation between the total HI mass and gas-phase metallicity at fixed stellar mass, but the anticorrelation is significantly strengthened when the total HI mass is replaced by the inner HI mass. Introducing a secondary relation with the inner HI mass can produce a small but noticeable decrease (16%) in the scatter of the mass-gas-phase metallicity relation, in contrast to the negligible effect with the SFR. The correlation with the inner HI mass is robust when using different diagnostics of metallicity, but the correlation with SFR is not. The correlation with the inner HI mass becomes much weaker when the gas-phase metallicity is derived in the central region instead of at the effective radius. These results support the idea that the scatter in the mass-metallicity relation is regulated by gas accretion, and not directly by the SFR, and stress the importance of deriving the gas mass and the metallicity from roughly the same region. The new relation between inner HI mass and gas-phase metallicity will provide new constraints for chemical and galaxy evolution models.
In this paper, we stack neutral atomic hydrogen (HI) spectra for 9,720 star forming galaxies along the mass-metallicity relation. The sample is selected according to stellar mass (10$^9 \leq$ M$_{\star}$/M$_{\odot}\leq$10$^{11}$) and redshift ($0.02 \leq z \leq 0.05$) from the overlap of the Sloan Digital Sky Survey and Arecibo Legacy Fast ALFA survey. We confirm and quantify the strong anti-correlation between HI mass and gas-phase metallicity at fixed stellar mass. Furthermore, we show for the first time that the relationship between gas content and metallicity is consistent between differen…
We study the metallicity dependence of the H/H$_2$ and C$^+$/C/CO distributions in a self-regulated interstellar medium (ISM) across a broad range of metallicities ($0.1 < Z/Z_\odot < 3$). To this end, we conduct high-resolution (particle mass of $1\ {\rm M_\odot}$) hydrodynamical simulations coupled with a time-dependent H$_2$ chemistry network. The results are then post-processed with an accurate chemistry network to model the associated C$^+$/C/CO abundances, based on the time-dependent non-steady-state (``non-equilibrium'') H$_2$ abundances. We find that the time-averaged star formation ra…
In this paper we present an exact general analytic expression $Z(sSFR)=y/Λ(sSFR)+I(sSFR)$ linking the gas metallicity Z to the specific star formation rate (sSFR), that validates and extends the approximate relation put forward by Lilly et al. (2013, L13), where $y$ is the yield per stellar generation, $Λ(sSFR)$ is the instantaneous ratio between inflow and star formation rate expressed as a function of the sSFR, and $I$ is the integral of the past enrichment history, respectively. We then demonstrate that the instantaneous metallicity of a self-regulating system, such that its sSFR decreases …
We present the integrated stellar mass-metallicity relation (MZR) for more than 1700 galaxies included in the integral field area SDSS-IV MaNGA survey. The spatially resolved data allow us to determine the metallicity at the same physical scale (effective radius in arcsecs, $\mathrm{R_{eff}}$ ) using a heterogeneous set of ten abundance calibrators. Besides scale factors, the shape of the MZR is similar for all calibrators, consistent with those reported previously using single-fiber and integral field spectroscopy. We compare the residuals of this relation against the star formation rate (SFR…
We examine the scatter of the relation between stellar mass and stellar metallicity for cluster dwarf galaxies in the cosmological simulation Illustris. The mass-metallicity relation exhibits the smallest intrinsic scatter at the galaxies' times of peak stellar mass, suggesting stellar mass stripping to be the primary effect responsible for the rather broad relation at present. However, for about 40% of galaxies in the high-metallicity tail of the relation, we find mass stripping to coincide with an increased enrichment of stellar metallicity, possibly caused by the stripping of low-metallicit…
Effective stellar feedback is used in models of galaxy formation to drive realistic galaxy evolution. Models typically include energy injection from supernovae as the dominant form of stellar feedback, often in some form of sub-grid recipe. However, it has been recently suggested that pre-SN feedback (stellar winds or radiation) is necessary in high-resolution simulations of galaxy evolution to properly regulate star formation and properties of the interstellar medium (ISM). Following these processes is computationally challenging, so many prescriptions model this feedback approximately, accou…
The existence of a spatially resolved Star-Forming Main Sequence (rSFMS) and a spatially resolved Mass-Metallicity Relation (rMZR) is now well established for local galaxies. Moreover, gradients with metallicity decreasing with radius seem to be common in local disc galaxies. These observations suggest that galaxy formation is a self-regulating process, and provide constraints for galaxy evolution models. Studying the evolution of these relations at higher redshifts is still however very challenging. In this paper, we analyse three gravitationally lensed galaxies at z = 0.6, 0.7 and 1, observe…
In this paper, we take advantage of the GAlaxy Evolution and Assembly (GAEA) semi-analytic model to analyse the origin of secondary dependencies in the local galaxy mass - gas metallicity relation. Our model reproduces quite well the trends observed in the local Universe as a function of galaxy star formation rate and different gas-mass phases. We show that the cold gas content (whose largest fraction is represented by the atomic gas phase) can be considered as the third parameter governing the scatter of the predicted mass-metallicity relation, in agreement with the most recent observational …
The physical origin of the scatter in the relation between galaxy stellar mass and the metallicity of the interstellar medium, i.e. the Mass-Metallicity Relation (MZR), reflects the relative importance of key processes in galaxy evolution. The \eagle cosmological hydrodynamical simulation is used to investigate the correlations between the residuals of the MZR and the residuals of the relations between stellar mass and, respectively, specific inflow, outflow and star formation rate as well as the gas fraction for central galaxies. At low redshift, all these residuals are found to be anti-corre…
Does the Fundamental Metallicity Relation Evolve with Redshift? I: The Correlation Between Offsets from the Mass-Metallicity Relation and Star Formation Rate
We present the stellar mass ($M_{*}$)--gas-phase metallicity relation (MZR) and its scatter at intermediate redshifts ($0.5\leq z\leq0.7$) for 1381 field galaxies collected from deep spectroscopic surveys. The star formation rate (SFR) and color at a given $M_{*}$ of this magnitude-limited ($R\lesssim24$ AB) sample are representative of normal star-forming galaxies. For masses below $10^9 M_\odot$, our sample of 237 galaxies is $\sim$10 times larger than those in previous studies beyond the local universe. This huge gain in sample size enables superior constraints on the MZR and its scatter in…
We train a deep residual convolutional neural network (CNN) to predict the gas-phase metallicity ($Z$) of galaxies derived from spectroscopic information ($Z \equiv 12 + \log(\rm O/H)$) using only three-band $gri$ images from the Sloan Digital Sky Survey. When trained and tested on $128 \times 128$-pixel images, the root mean squared error (RMSE) of $Z_{\rm pred} - Z_{\rm true}$ is only 0.085 dex, vastly outperforming a trained random forest algorithm on the same data set (RMSE $=0.130$ dex). The amount of scatter in $Z_{\rm pred} - Z_{\rm true}$ decreases with increasing image resolution in a…
Using cosmological galaxy simulations from the MaGICC project, we study the evolution of the stellar masses, star formation rates and gas phase abundances of star forming galaxies. We derive the stellar masses and star formation rates using observational relations based on spectral energy distributions by applying the new radiative transfer code GRASIL-3D to our simulated galaxies. The simulations match well the evolution of the stellar mass-halo mass relation, have a star forming main sequence that maintains a constant slope out to redshift z $\sim$ 2, and populate projections of the stellar …
The metallicity and its relationship with other galactic properties is a fundamental probe of the evolution of galaxies. In this work, we select about 750,000 star-forming spatial pixels from 1122 blue galaxies in the MaNGA survey to investigate the global stellar mass - local stellar mass surface density - gas-phase metallicity ($M_*$ - $Σ_*$ - $Z$ ) relation. At a fixed $M_*$, the metallicity increases steeply with increasing $Σ_*$. Similarly, at a fixed $Σ_*$, the metallicity increases strongly with increasing $M_*$ at low mass end, while this trend becomes less obvious at high mass end. We…
We investigate the mass-metallicity relation and its dependence on galaxy physical properties with a sample of 703 Lyman-break analogues (LBAs) in local Universe, which have similar properties to high redshift star-forming galaxies. The sample is selected according to $\ha$ luminosity, $L(\ha)>10^{41.8}\,{\rm erg\,s^{-1}}$, and surface brightness, $I(\ha)>10^{40.5}\,{\rm erg\,s^{-1}\,kpc^{-2}}$, criteria. The mass-metallicity relation of LBAs harmoniously agrees with that of star-forming galaxies at $z \sim$ 1.4-1.7 in stellar mass range of $10^{8.5}M_{\odot}<M_{*}<10^{11}M_{\odot}$. The relat…
In this work, we explore the diversity of ionised gas kinematics (rotational velocity $v_ϕ$ and velocity dispersion $σ_{\mathrm{g}}$) and gas-phase metallicity gradients at $0.1 \leq z \leq 2.5$ using a compiled data set of 74 galaxies resolved with ground-based integral field spectroscopy. We find that galaxies with the highest and the lowest $σ_{\mathrm{g}}$ have preferentially flat metallicity gradients, whereas those with intermediate values of $σ_{\mathrm{g}}$ show a large scatter in the metallicity gradients. Additionally, steep negative gradients appear almost only in rotation-dominated…
The relationships between stellar mass, gas-phase metallicity and star formation rate (i.e. the Mass-Metallicity, MZR, and the Fundamental Metallcity Relation, FMR) in the local Universe are revisited by fully anchoring the metallicity determination for SDSS galaxies on the Te abundance scale defined exploiting the strong-line metallicity calibrations presented in Curti et al. (2017). Self-consistent metallicity measurements allow a more unbiased assessment of the scaling relations involving M, Z and SFR, which provide powerful constraints for the chemical evolution models. We parametrise the …
The stellar metallicity gradients of disc galaxies provide information on the disc assembly, star formation processes and chemical evolution. They also might store information on dynamical processes which could affect the distribution of chemical elements in the gas-phase and the stellar components. We studied the stellar metallicity gradients of stellar discs in a cosmological simulation. We explored the dependence of the stellar metallicity gradients on stellar age and the size and mass of the stellar discs. We used galaxies selected from a cosmological hydrodynamical simulation performed in…
Auriga Streams III: the mass-metallicity relation does not rule out tidal mass loss in Local Group satellites
Durham University（杜伦大学）；Lund University（隆德大学）；University of Zurich（苏黎世大学）；University of Washington（华盛顿大学）；Argonne National Laboratory（阿贡国家实验室）；Universidad de La Serena（拉塞雷纳大学）；University of Bologna（博洛尼亚大学）；INAF, Astrophysics and Space Science Observatory Bologna（意大利国家天体物理研究所博洛尼亚天文与空间科学观测站）；Liverpool John Moores University（利物浦约翰摩尔斯大学）
Galaxies at low-redshift typically possess negative gas-phase metallicity gradients (centres more metal-rich than their outskirts). Whereas, it is not uncommon to observe positive metallicity gradients in higher-redshift galaxies ($z \gtrsim 0.6$). Bridging these epochs, we present gas-phase metallicity gradients of 84 star-forming galaxies between $0.08 < z < 0.84$. Using the galaxies with reliably determined metallicity gradients, we measure the median metallicity gradient to be negative ($-0.039^{+0.007}_{-0.009}$ dex/kpc). Underlying this, however, is significant scatter: $(8\pm3)\%\ [7]$ …
Revisiting the mass metallicity relation and the fundamental metallicity relation of dwarf galaxies at cosmic noon with NIRISS
School of Astronomy and Space Science, University of Chinese Academy of Sciences (UCAS)（中国科学院大学天文与空间科学学院）；Department of Astronomy, School of Physics and Technology, Wuhan University（武汉大学物理科学与技术学院天文学系）；Department of Physics and Astronomy, University of California, Los Angeles（加州大学洛杉矶分校物理与天文学系）；Cosmic Dawn Center (DAWN)（宇宙黎明中心）；Niels Bohr Institute, University of Copenhagen（哥本哈根大学尼尔斯·玻尔研究所）；Department of Astronomy, Tsinghua University（清华大学天文学系）；National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）；Institute for Frontiers in Astronomy and Astrophysics, Beijing Normal University（北京师范大学天文与前沿科学研究院）；Department of Physics and Astronomy, University of California Davis（加州大学戴维斯分校物理与天文学系）
Using a sample of dwarf galaxies observed using the VIMOS IFU on the VLT, we investigate the mass-metallicity relation (MZR) as a function of star formation rate (FMR$_{\text{SFR}}$) as well as HI-gas mass (FMR$_{\text{HI}}$). We combine our IFU data with a subsample of galaxies from the ALFALFA HI survey crossmatched to the Sloan Digital Sky Survey to study the FMR$_{\text{SFR}}$ and FMR$_{\text{HI}}$ across the stellar mass range 10$^{6.6}$ to 10$^{8.8}$ M$_\odot$, with metallicities as low as 12+log(O/H) = 7.67. We find the 1$σ$ mean scatter in the MZR to be 0.05 dex. The 1$σ$ mean scatter …
We use our integrated SDSS photometry for 96 globular clusters in $g$ and $z$, as well as $r$ and $i$ photometry for a subset of 56 clusters, to derive the integrated colour-metallicity relation (CMR) for Galactic globular clusters. We compare this relation to previous work, including extragalactic clusters, and examine the influence of age, present-day mass function variations, structural parameters and the morphology of the horizontal branch on the relation. Moreover, we scrutinise the scatter introduced by foreground extinction (including differential reddening) and show that the scatter in…
We present updated metallicity relations for the spectral database of star-forming galaxies (SFGs) found in the KPNO International Spectroscopic Survey (KISS). New spectral observations of emission-line galaxies (ELGs) obtained from a variety of telescope facilities provide oxygen abundance information. A nearly four-fold increase in the number of KISS objects with robust metallicities relative to our previous analysis provides for an empirical abundance calibration to compute self-consistent metallicity estimates for all SFGs in the sample with adequate spectral data. In addition, a sophistic…
The coevolution of galaxies and their metal content serves as an important test for galaxy feedback models. We analyze the distribution and evolution of metals within the IllustrisTNG simulation suite with a focus on the gas-phase mass-metallicity relation (MZR). We find that the IllustrisTNG model broadly reproduces the slope and normalization evolution of the MZR across the redshift range $0<z<2$ and mass range $10^9 < M_*/\mathrm{M}_\odot < 10^{10.5}$. We make predictions for the high redshift ($2<z<10$) metal content of galaxies which is described by a gradual decline in the normalization …
We use Milky Way-like chemodynamical simulations with a new treatment for dust destruction and growth to investigate how these two processes affect the properties of the interstellar medium in galaxies. We focus on the role of two specific parameters: f_des (a new parameter that determines the fraction of dust destroyed in a single gas particle surrounding supernova) and C_s (the probability that a metal atom or ion sticks to the dust grain after colliding, i.e., the sticking coefficient) in regulating the amount and distribution of dust, cold gas and metals in galaxies. We find that simulated…
Galaxy Metallicity Gradients in the Reionization Epoch from the FIRE-2 Simulations
University of Chinese Academy of Sciences (UCAS)（中国科学院大学）；National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）；Institute for Frontiers in Astronomy and Astrophysics, Beijing Normal University（北京师范大学前沿交叉科学研究院）；Kavli Institute for Astronomy and Astrophysics, Peking University（北京大学科维理天文与天体物理研究所）；Department of Astronomy, University of Massachusetts, Amherst（马萨诸塞大学阿默斯特分校天文学系）；Department of Astronomy, School of Physics, Peking University（北京大学物理学院天文学系）；Department of Astronomy and Theoretical Astrophysics Center, University of California Berkeley（加州大学伯克利分校天文学系和理论天体物理中心）；Department of Physics and Astronomy, University of California, Davis（加州大学戴维斯分校物理与天文学系）
Understanding the relationship between the cosmic web and the gas content of galaxies is a key step towards understanding galaxy evolution. However, the impact of the cosmic web on the growth of galaxies and dark matter halos is not yet properly understood. We report a detection of the effect of the cosmic web on the galaxy stellar mass - gas phase metallicity relation of low redshift star-forming galaxies, using SDSS data. The proximity of a galaxy to a node, independently of stellar mass and overdensity, influences its gas-phase metallicity, with galaxies closer to nodes displaying higher ch…
We present a comprehensive study of the relations between gas kinematics, metallicity, and stellar mass in a sample of 82 GRB-selected galaxies using absorption and emission methods. We find the velocity widths of both emission and absorption profiles to be a proxy of stellar mass. We also investigate the velocity-metallicity correlation and its evolution with redshift and find the correlation derived from emission lines to have a significantly smaller scatter compared to that found using absorption lines. Using 33 GRB hosts with measured stellar mass and metallicitiy, we study the mass-metall…
Observations of the Milky Way's low-$α$ disk show that at fixed metallicity, [Fe/H], several element abundance, [X/Fe], correlate with age, with unique slopes and small scatters around the age-[X/Fe] relations. In this study, we turn to simulations to explore the age-[X/Fe] relations for the elements C, N, O, Mg, Si, S, and Ca that are traced in a FIRE-2 cosmological zoom-in simulation of a Milky Way-like galaxy, m12i, and understand what physical conditions give rise to the observed age-[X/Fe] trends. We first explore the distributions of mono-age populations in their birth and current locati…
We present hitherto the largest sample of gas-phase metallicity radial gradients measured at sub-kiloparsec resolution in star-forming galaxies in the redshift range of $z\in[1.2, 2.3]$. These measurements are enabled by the synergy of slitless spectroscopy from the Hubble Space Telescope near-infrared channels and the lensing magnification from foreground galaxy clusters. Our sample consists of 76 galaxies with stellar mass ranging from 10$^7$ to 10$^{10}$ $M_\odot$, instantaneous star-formation rate in the range of [1, 100] $M_\odot$/yr, and global metallicity [$\frac{1}{12}$, 2] solar. At 2…
ALMA Chemical Evolution (ACE) survey: The gas fundamental metallicity relation at cosmic noon
Centro de Astrobiología (CAB), CSIC-INTA（西班牙国家研究委员会-国家航空航天技术研究所 天体生物学中心（CAB））；Leiden University（莱顿大学）；Australian National University（澳大利亚国立大学）；University of Florida（佛罗里达大学）；University of Copenhagen（哥本哈根大学）；Technical University of Denmark（丹麦技术大学）
Motivated by the observed bottom-light initial mass function (IMF) in faint dwarfs, we study how a metallicity-dependent IMF affects the feedback budget and observables of an ultra-faint dwarf galaxy. We model the evolution of a low-mass ($\approx 8 \, \times \, 10^{8} \, \rm M_{\odot}$) dark matter halo with cosmological, zoomed hydrodynamical simulations capable of resolving individual supernovae explosions, which we complement with an empirically motivated subgrid prescription for systematic IMF variations. In this framework, at the low gas metallicities typical of faint dwarfs, the IMF of …
We report on the gas-phase metallicity gradients of a sample of 264 star-forming galaxies at 0.6 < z < 2.6, measured through deep near-infrared Hubble Space Telescope slitless spectroscopy. The observations include 12-orbit depth Hubble/WFC3 G102 grism spectra taken as a part of the CANDELS Lya Emission at Reionization (CLEAR) survey, and archival WFC3 G102+G141 grism spectra overlapping the CLEAR footprint. The majority of galaxies (84%) in this sample are consistent with a zero or slightly positive metallicity gradient across the full mass range probed (8.5 < log M_*/M_sun < 10.5). We measur…
We present a newly observed relation between galaxy mass and radial metallicity gradients of early-type galaxies. Our sample of 51 early-type galaxies encompasses a comprehensive mass range from dwarf to brightest cluster galaxies. The metallicity gradients are measured out to one effective radius by comparing nearly all of the Lick absorption-line indices to recent models of single stellar populations. The relation shows very different behaviour at low and high masses, with a sharp transition being seen at a mass of ~ 3.5 x 10^10 M_sun (velocity dispersion of ~140 km/s, M_B ~ -19). Low-mass g…
We present observations of CO(3-2) in 13 main-sequence $z=2.0-2.5$ star-forming galaxies at $\log(M_*/M_{\odot})=10.2-10.6$ that span a wide range in metallicity (O/H) based on rest-optical spectroscopy. We find that CO(3-2)/SFR decreases with decreasing metallicity, implying that the CO luminosity per unit gas mass is lower in low-metallicity galaxies at $z\sim2$. We constrain the CO-to-H$_2$ conversion factor ($α_{\text{CO}}$) and find that $α_{\text{CO}}$ inversely correlates with metallicity at $z\sim2$. We derive molecular gas masses ($M_{\text{mol}}$) and characterize the relations among…
The metallicity of star-forming gas in galaxies from the EAGLE simulations increases with stellar mass. Here we investigate whether the scatter around this relation correlates with morphology and/or stellar kinematics. At redshift $z=0$, galaxies with more rotational support have lower metallicities on average when the stellar mass is below $M_\star\approx 10^{10}~{\rm M}_\odot$. This trend inverts at higher values of $M_\star$, when prolate galaxies show typically lower metallicity. At increasing redshifts, the trend between rotational support and metallicity becomes weaker at low stellar mas…
We have collected spectra of about 2000 red giant branch (RGB) stars in 19 Galactic globular clusters (GC) using FLAMES@VLT (about 100 star with GIRAFFE and about 10 with UVES, respectively, in each GC). These observations provide an unprecedented, precise, and homogeneous data-set of Fe abundances in GCs. We use it to study the cosmic scatter of iron and find that, as far as Fe is concerned, most GCs can still be considered mono-metallic, since the upper limit to the scatter in iron is less than 0.05 dex, meaning that the degree of homogeneity is better than 12%. The scatter in Fe we find see…
Chemical abundance variations in the ISM provide important information about the galactic evolution, star-formation and enrichment histories. Recent observations of disk galaxies suggest that if large-scale azimuthal metallicity variations appear in the ISM, they are linked to the spiral arms. In this work, using a set of chemodynamical simulations of the Milky Way-like spiral galaxies, we quantify the impact of gas radial motions~(migration) in the presence of a pre-existing radial metallicity gradient and the local ISM enrichment on both global and local variations of the mean ISM metallicit…
We develop a theoretical framework that extracts a deeper understanding of galaxy formation from empirically-derived relations among galaxy properties by extending the main-sequence integration method for computing galaxy star formation histories. We properly account for scatter in the stellar mass-star formation rate relation and the evolving fraction of passive systems and find that the latter effect is almost solely responsible for the age distributions among $z\sim0$ galaxies with stellar masses above $\sim 10^{10}\,{\rm M_{\odot}}$. However, while we qualitatively agree with the observed …
Current galaxy observations suggest that a roughly linear correlation exists between the [CII] emission and the star formation rate, either as spatially-resolved or integrated quantities. Observationally, this correlation seems to be independent of metallicity, but the very large scatter does not allow to properly assess whether this is true. On the other hand, theoretical models tend to suggest a metallicity dependence of the correlation. In this study, we investigate the metallicity evolution of the correlation via a high-resolution zoom-in cosmological simulation of a dwarf galaxy employing…
More fundamental than the fundamental metallicity relation: The effect of the stellar metallicity on the gas-phase mass-metallicity and gravitational potential-metallicity relations
Observed and simulated galaxies exhibit correlations between stellar mass, metallicity and morphology. We use the EAGLE cosmological simulation to examine the origin of these correlations for galaxies in the stellar mass range $10^9~\rm{M_\odot} \leqslant\ M_\star \leqslant 10^{10}~\rm{M_\odot}$, and the extent to which they contribute to the scatter in the mass-metallicity relation. We find that rotationally supported disc galaxies have lower metallicity than dispersion supported spheroidal galaxies at a given mass, in agreement with previous findings. In EAGLE, this correlation arises becaus…
We present the discovery and spectrophotometric characterization of a large sample of 164 faint ($i_{AB}$ $\sim$ $23$-$25$ mag) star-forming dwarf galaxies (SFDGs) at redshift $0.13$ $\leq z \leq$ $0.88$ selected by the presence of bright optical emission lines in the VIMOS Ultra Deep Survey (VUDS). We investigate their integrated physical properties and ionization conditions, which are used to discuss the low-mass end of the mass-metallicity relation (MZR) and other key scaling relations. We use optical VUDS spectra in the COSMOS, VVDS-02h, and ECDF-S fields, as well as deep multiwavelength p…
Star-forming galaxies display a close relation among stellar mass, metallicity and star-formation rate (or molecular-gas mass). This is known as the fundamental metallicity relation (FMR) (or molecular-gas FMR), and it has a profound implication on models of galaxy evolution. However, there still remains a significant residual scatter around the FMR. We show here that a fourth parameter, the surface density of stellar mass, reduces the dispersion around the molecular-gas FMR. In a principal component analysis of 29 physical parameters of 41,338 star-forming galaxies, the surface density of ste…
We present an analysis of spatially resolved gas-phase metallicity relations in five dwarf galaxies ($M_{halo} \approx 10^{11} M_\odot$, $M_\star \approx 10^{8.8}-10^{9.6} M_\odot$) from the FIRE-2 (Feedback in Realistic Environments) cosmological zoom-in simulation suite, which include an explicit model for sub-grid turbulent mixing of metals in gas, near $z\approx 0$, over a period of 1.4 Gyrs, and compare our findings with observations. While these dwarf galaxies represent a diverse sample, we find that all simulated galaxies match the observed mass-metallicity (MZR) and mass-metallicity gr…
We investigate the use of the [O II] $\lambda3727$ emission line as a star formation rate (SFR) estimator using Sloan Digital Sky Spectra for nearly 100,000 star-forming galaxies and 5,500 galaxies with narrow-line active galactic nuclei. Consistent with previous work, we find that the [O II]/H$α$ ratio in star-forming galaxies depends strongly on gas-phase metallicity. Using metallicities derived from the [N II] $λ6584$/[O II] $λ3727$ method, we refine a metallicity-dependent SFR estimator based on [O II] that is calibrated within a scatter of 0.056 dex against the more commonly used SFR indi…
Using the catalogues of galaxy clusters from The Three Hundred project, modelled with both hydrodynamic simulations, (Gadget-X and Gadget-MUSIC), and semi-analytic models (SAMs), we study the scatter and self-similarity of the profiles and distributions of the baryonic components of the clusters: the stellar and gas mass, metallicity, the stellar age, gas temperature, and the (specific) star formation rate. Through comparisons with observational results, we find that the shape and the scatter of the gas density profiles matches well the observed trends including the reduced scatter at large ra…
We investigate the star formation rate (SFR) dependence on the stellar mass and gas-phase metallicity relation at z=2 with MOSFIRE/Keck as part of the ZFIRE survey. We have identified 117 galaxies (1.98 < z < 2.56), with $8.9\leq$log(M/M$_{\odot}$)$\leq11.0$, for which we can measure gas-phase metallicities. For the first time, we show discernible difference between the mass-metallicity relation, using individual galaxies, when deviding the sample by low ($<10$~M$_{\odot}$yr$^{-1}$) and high ($>10$~M$_{\odot}$yr$^{-1}$) SFRs. At fixed mass, low star-forming galaxies tend to have higher metalli…
The distributions of a galaxy's gas and stars in chemical space encodes a tremendous amount of information about that galaxy's physical properties and assembly history. However, present methods for extracting information from chemical distributions are based either on coarse averages measured over galactic scales (e.g., metallicity gradients) or on searching for clusters in chemical space that can be identified with individual star clusters or gas clouds on $\sim 1$ pc scales. These approaches discard most of the information, because in galaxies gas and young stars are observed to be distribut…
Making use of both MUSE observations of 85 galaxies from the survey GASP (GAs Stripping Phenomena in galaxies with MUSE) and a large sample from MaNGA (Mapping Nearby Galaxies at Apache Point Observatory survey) we investigate the distribution of gas metallicity gradients as a function of stellar mass, for local cluster and field galaxies. Overall, metallicity profiles steepen with increasing stellar mass up to $10^{10.3}\,{\rm M_\odot}$ and flatten out at higher masses. Combining the results from the metallicity profiles and the stellar mass surface density gradients, we propose that the obse…
We use a sample of star-forming field and protocluster galaxies at z=2.0-2.5 with Keck/MOSFIRE K-band spectra, a wealth of rest-frame UV photometry, and Spitzer/MIPS and Herschel/PACS observations, to dissect the relation between the ratio of IR to UV luminosity (IRX) versus UV slope ($β$) as a function of gas-phase metallicity (12+log(O/H)~8.2-8.7). We find no significant dependence of the IRX-$β$ trend on environment. However, we find that at a given $β$, IRX is highly correlated with metallicity, and less correlated with mass, age, and sSFR. We conclude that, of the physical properties test…
