Observations of galaxies in the local Universe have shown that both the ionized gas and the stars of satellites are more metal-rich than of equally massive centrals. To gain insight into the connection between this metallicity enhancement and other differences between centrals and satellites, such as their star formation rates, gas content, and growth history, we study the metallicities of >3600 galaxies with M_star > 10^10 M_sun in the cosmological hydrodynamical EAGLE 100 Mpc `Reference' simulation, including ~1500 in the vicinity of galaxy groups and clusters (M_200 >= 10^13 M_sun). The simulation predicts excess gas and stellar metallicities in satellites consistent with observations, except for stellar metallicities at M_star <~ 10^10.2 M_sun where the predicted excess is smaller than observed. The exact magnitude of the effect depends on galaxy selection, aperture, and on whether the metallicity is weighted by stellar mass or luminosity. The stellar metallicity excess in clusters is also sensitive to the efficiency scaling of star formation feedback. We identify stripping of low-metallicity gas from the galaxy outskirts, as well as suppression of metal-poor inflows towards the galaxy centre, as key drivers of the enhancement of gas metallicity. Stellar metallicities in satellites are higher than in the field as a direct consequence of the more metal-rich star forming gas, whereas stripping of stars and suppressed stellar mass growth, as well as differences in accreted vs. in-situ star formation between satellites and the field, are of secondary importance.
We present global metallicity properties, metallicity distribution functions (MDFs) and radial metallicity profiles for the six most luminous M31 dwarf galaxy satellites: M32, NGC 205, NGC 185, NGC 147, Andromeda VII, and Andromeda II. The results presented are the first spectroscopic MDFs for dwarf systems surrounding a host galaxy other than the Milky Way. Our sample consists of individual metallicity measurements for 1243 red giant branch (RGB) member stars spread across these six systems. We determine metallicities based on the strength of the Ca II triplet lines using the empirical calibr…
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）
We study the role of environment in the evolution of central and satellite galaxies with the Sloan Digital Sky Survey. We begin by studying the size-mass relation, replicating previous studies, which showed no difference between the sizes of centrals and satellites at fixed stellar mass, before turning our attention to the size-core velocity dispersion ($σ_0$) and mass-$σ_0$ relations. By comparing the median size and mass of the galaxies at fixed velocity dispersion we find that the central galaxies are consistently larger and more massive than their satellite counterparts in the quiescent po…
The present-day Age-Metallicity Relation (AMR) is a record of the star formation history of the Galaxy, as this traces the chemical enrichment of the gas over time. We use a zoomed-in cosmological simulation that reproduces key signatures of the Milky Way (MW), g2.79e12 from the NIHAO-UHD project, to examine how stellar migration and satellite infall shape the AMR across the disk. We find in the simulation, similar to the MW, the AMR in small spatial regions (R, z) shows turning points that connect changes in the direction of the relations. The turning points in the AMR in the simulation, are …
We investigate the environmental dependence of the local gas-phase metallicity in a sample of star-forming galaxies from the MaNGA survey. Satellite galaxies with stellar masses in the range $9<\log(M_{*}/M_{\odot})<10$ are found to be $\sim 0.05 \, \mathrm{dex}$ higher in metallicity than centrals of similar stellar mass. Within the low-mass satellite population, we find that the interstellar medium (ISM) metallicity depends most strongly on the stellar mass of the galaxy that is central to the halo, though there is no obvious difference in the metallicity gradients. At fixed total stellar ma…
Recent studies have found higher galaxy metallicities in richer environments. It is not yet clear, however, whether metallicity-environment dependencies are merely an indirect consequence of environmentally dependent formation histories, or of environment related processes directly affecting metallicity. Here, we present a first detailed study of metallicity-environment correlations in a cosmological hydrodynamical simulation, in particular the Illustris simulation. Illustris galaxies display similar relations to those observed. Utilizing our knowledge of simulated formation histories, and lev…
Observations reveal a universal stellar mass-stellar metallicity relation (MZR) existing in Local Group dwarfs of different types, $Z_*\propto M_*^α$ with $α=0.30\pm0.02$. In this work, we investigate the "universality" of the MZRs for both satellites and central galaxies in a large number of different host dark matter halos covering a large mass range of $10^9$-$10^{15}h^{-1}M_\odot$, by using a semianalytical galaxy formation and evolution model. We obtain the following results. (1) The exponents ($α$) for the MZRs of the satellites in halos with the same mass as the Milky Way halo but diffe…
Satellite Metallicity Enhancement I: Suppressed Star Formation, Stellar Mass Loss, and Enriched Inflow of DESI and EAGLE Galaxies around Massive Clusters
State Key Laboratory of Dark Matter Physics & Tsung-Dao Lee Institute, Shanghai Jiao Tong University（暗物质物理国家重点实验室暨李政道研究所，上海交通大学）；Department of Astronomy, School of Physics and Astronomy, Shanghai Jiao Tong University（上海交大物理与天文学院天文学系）；Lawrence Berkeley National Laboratory（劳伦斯伯克利国家实验室）；Department of Physics, Boston University（波士顿大学物理系）；Department of Physics & Astronomy, University College London（伦敦大学学院物理与天文系）；Instituto de Física, Universidad Nacional Autónoma de México（墨西哥国立自治大学物理研究所）
Using LAMOST spectroscopic data, we find a strong signal of a comoving group of stars in the constellation of Draco. The group, observed near the apocenter of its orbit, is 2.6 kpc from the Sun with a metallicity of -0.64 dex. The system is observed as a streaming population of unknown provenance with mass of about 2.1E4 solar masses and an absolute V band magnitude of about -3.6. Its high metallicity, diffuse physical structure, and eccentric orbit may indicate that the progenitor satellite was a globular cluster rather than a dwarf galaxy or an open cluster.
We present an extensive study of the Sagittarius II (Sgr II) stellar system using MegaCam g and i photometry, narrow-band, metallicity-sensitive Calcium H&K doublet photometry, augmented with Keck II/DEIMOS multi-object spectroscopy. We are able to derive and refine the Sgr II structural and stellar properties: the colour-magnitude diagram implies Sgr II is old (12.0 +- 0.5 Gyr) and metal-poor. The CaHK photometry confirms the metal-poor nature of the satellite ([Fe/H]CaHK = -2.32 +- 0.04 dex) and suggests that Sgr II hosts more than one single stellar population (σ CaHK = 0.11+0.05-0.03 dex).…
A number of Local Group dwarf galaxies are known to have two spatially segregated stellar metallicity populations, a centrally concentrated metal-rich population and a more extended metal-poor population. In this work we discuss mechanisms that lead to the formation of two spatially segregated metallicity populations. Using a set of high-resolution hydrodynamical simulations of Local Group-like environments, we select a sample of satellite and field galaxies, spanning the stellar mass range $10^6-10^9$M$_{\odot}$, that exhibit bimodality in their metallicity distributions. Among those, we iden…
We develop a new analysis method that allows us to compare multi-dimensional observables to a theoretical model. The method is based on unsupervised clustering algorithms which assign the observational and simulated data to clusters in high dimensionality. From the clustering result, a goodness of fit (the p-value) is determined with the Fisher-Freeman-Halton test. We first show that this approach is robust for 2D Gaussian distributions. We then apply the method to the observed MW satellites and simulated satellites from the fiducial model of our semi-analytic code A-SLOTH. We use the followin…
We explore the chemical distribution of stars in a simulated galaxy. Using simulations of the same initial conditions but with two different feedback schemes (MUGS and MaGICC), we examine the features of the age-metallicity relation (AMR), and the three-dimensional age-metallicity-[O/Fe] distribution, both for the galaxy as a whole and decomposed into disc, bulge, halo, and satellites. The MUGS simulation, which uses traditional supernova feedback, is replete with chemical substructure. This sub- structure is absent from the MaGICC simulation, which includes early feedback from stellar winds, …
Observations and semianalytical galaxy formation and evolution models (SAMs) have suggested the existence of a stellar mass-stellar metallicity relation (MZR), which is shown to be universal for different types of galaxies over a large range of stellar masses ($M_*\sim 10^3$-$10^{11}M_\odot$) and dark matter (DM) halo masses ($M_{\rm halo}\sim 10^9$-$10^{15}h^{-1}M_\odot$). In this work, we construct a chemical evolution model to investigate the origin of the MZR, including both the effects of gas inflows and outflows in galaxies. We solve the MZR from the chemical evolution model, by assuming…
The chemical compositions of the stars in Milky Way (MW) satellite galaxies reveals the history of gas flows and star formation (SF) intensity. This talk presented a Keck/DEIMOS spectroscopic survey of the Fe, Mg, Si, Ca, and Ti abundances of nearly 3000 red giants in eight MW dwarf satellites. The metallicity and alpha-to-iron ratio distributions obey the following trends: (1) The more luminous galaxies are more metal-rich, indicating that they retained gas more efficiently than the less luminous galaxies. (2) The shapes of the metallicity distributions of the more luminous galaxies require g…
We study the mass spectrum of destroyed dwarfs that contribute to the accreted stellar mass of Milky Way (MW) mass M_vir ~ 10^12.1 M_sun) halos using a suite of 45 zoom-in, dissipationless simulations. Empirical models are employed to relate (peak) subhalo mass to dwarf stellar mass, and we use constraints from z=0 observations and hydrodynamical simulations to estimate the metallicity distribution of the accreted stellar material. The dominant contributors to the accreted stellar mass are relatively massive dwarfs with M_star ~ 10^8-10^10 M_sun. Halos with more quiescent accretion histories t…
In this paper, we study the chemical properties of the stars in the dwarf satellites around the MW-like host galaxies, and explore the possible effects of several baryonic processes, including supernova (SN) feedback, the reionization of the universe and H$_2$ cooling, on them and how current and future observations may put some constraints on these processes. We use a semi-analytical model to generate MW-like galaxies, for which a fiducial model can reproduce the luminosity function and the stellar metallicity--stellar mass correlation of the MW dwarfs. Using the simulated MW-like galaxies, w…
We present the results of a deep study of the isolated dwarf galaxies Andromeda XXVIII and Andromeda XXIX with Gemini/GMOS and Keck/DEIMOS. Both galaxies are shown to host old, metal-poor stellar populations with no detectable recent star formation, conclusively identifying both of them as dwarf spheroidal galaxies (dSphs). And XXVIII exhibits a complex horizontal branch morphology, which is suggestive of metallicity enrichment and thus an extended period of star formation in the past. Decomposing the horizontal branch into blue (metal poor, assumed to be older) and red (relatively more metal …
The Pristine Dwarf Galaxy Survey -- VII. The metallicity distributions of 12 Milky Way faint satellites
Ecole Polytechnique Fédérale de Lausanne (EPFL)（洛桑联邦理工学院）；Observatoire de Paris, Université PSL, Sorbonne Université, Université Paris Cité, CY Cergy Paris Université, CNRS（巴黎天文台，巴黎文理研究大学，索邦大学，巴黎西岱大学，塞吉-蓬图瓦兹大学，法国国家科学研究中心）；IFCA, Instituto de Física de Cantabria (UC-CSIC)（坎塔布里亚物理研究所（坎塔布里亚大学-西班牙国家研究委员会））；Observatoire astronomique de Strasbourg, Université de Strasbourg, CNRS（斯特拉斯堡天文台，斯特拉斯堡大学，法国国家科学研究中心）；Max-Planck-Institut für Astronomie（马克斯·普朗克天文学研究所）；School of Astronomy and Space Science, Nanjing University（南京大学天文与空间科学学院）；Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University), Ministry of Education（南京大学现代天文与天体物理教育部重点实验室）；Instituto de Astrofísica de Canarias（加那利天体物理学研究所）；Universidad de La Laguna（拉帕鲁纳大学）；Institute of Astronomy, Unive（天文学研究所）
Accreted stellar populations are comprised of the remnants of destroyed galaxies, and often dominate the `stellar haloes' of galaxies such as the Milky Way (MW). This ensemble of external contributors is a key indicator of the past assembly history of a galaxy. We introduce a novel statistical method that uses the unbinned metallicity distribution function (MDF) of a stellar population to estimate the mass spectrum of its progenitors. Our model makes use of the well-known mass-metallicity relation of galaxies and assumes Gaussian MDF distributions for individual progenitors: the overall MDF is…
We present metallicity distribution functions (MDFs) for the central regions of eight dwarf satellite galaxies of the Milky Way: Fornax, Leo I and II, Sculptor, Sextans, Draco, Canes Venatici I, and Ursa Minor. We use the published catalog of abundance measurements from the previous paper in this series. The measurements are based on spectral synthesis of iron absorption lines. For each MDF, we determine maximum likelihood fits for Leaky Box, Pre-Enriched, and Extra Gas (wherein the gas supply available for star formation increases before it decreases to zero) analytic models of chemical evolu…
The difference in stellar metallicity between red and blue galaxies with the same mass constrains the timescale over which red galaxies ceased to form stars. Here we investigate this constraint with the GalICS 2.0 semi-analytic model of galaxy formation. The advantage of this approach is that the time of pericentric passages for satellite galaxies and the mass-loading factor for galactic winds are not free parameters of the chemical evolution model. The former is determined by the N-body simulation used to construct the merger trees, the latter by the requirement that GalICS 2.0 should reprodu…
We present deep spectroscopy from Keck/DEIMOS of Andromeda I, III, V, VII, and X, all of which are dwarf spheroidal satellites of M31. The sample includes 256 spectroscopic members across all five dSphs. We confirm previous measurements of the velocity dispersions and dynamical masses, and we provide upper limits on bulk rotation. Our measurements confirm that M31 satellites obey the same relation between stellar mass and stellar metallicity as Milky Way (MW) satellites and other dwarf galaxies in the Local Group. The metallicity distributions show similar trends with stellar mass as MW satell…
A wealth of tiny galaxies populates the surroundings of the Milky Way. Some of these objects might have their origin as former satellites of the Large Magellanic Cloud. Examples of the importance of understanding how many systems are genuine satellites of the MW or the LMC are the implications that the number and mass function of satellites have for dark matter theories and the treatment of baryonic physics in simulations of structure formation. Here we aim at deriving the bulk motions and estimates of the internal velocity dispersion and metallicity properties in four recently discovered dist…
Metal Mayhem at z~7-10: Diversity and Evolution of Gas-Phase Metallicity Gradients
Kavli Institute for Cosmology, University of Cambridge（卡弗里宇宙学研究所，剑桥大学）；Cavendish Laboratory, University of Cambridge（卡文迪许实验室，剑桥大学）；Department of Physics and Astronomy, University College London（伦敦大学学院物理与天文学系）；Max-Planck-Institut für extraterrestrische Physik (MPE)（马普地外物理学研究所）；Centro de Astrobiología (CAB), CSIC–INTA（天体生物学中心（CAB），西班牙国家科学研究委员会-国家航空航天技术研究所）；DARK, Niels Bohr Institute, University of Copenhagen（DARK研究中心，尼尔斯·玻尔研究所，哥本哈根大学）
We examine the stellar population radial gradients (age, metallicity and [$α/$Fe]) of $\sim$ 100 passive central galaxies up to $\sim 2 R_e$. The targeted groups have a halo mass range spanning from $11 < \log(M_{200}/M_{\odot}) < 15$, in the SAMI Galaxy Survey. The main goal of this work is to determine whether central galaxies have different stellar population properties when compared to similarly massive satellite galaxies. We find negative metallicity radial gradients, which become shallower with increasing stellar mass. The age and [$α$/Fe] gradients are consistent with zero or slightly p…
We investigate the environmental dependence of the stellar populations of galaxies in SDSS DR7. Echoing earlier works, we find that satellites are both more metal-rich (<0.1 dex) and older (<2 Gyr) than centrals of the same stellar mass. However, after separating star-forming, green valley and passive galaxies, we find that the true environmental dependence of both stellar metallicity (<0.03 dex) and age (<0.5 Gyr) is in fact much weaker. We show that the strong environmental effects found when galaxies are not differentiated result from a combination of selection effects brought about by the …
Using a large SDSS galaxy group catalogue, we study how the stellar ages and metallicities of central and satellite galaxies depend on stellar mass and halo mass. We find that satellites are older and metal-richer than centrals of the same stellar mass. In addition, the slopes of the age-stellar mass and metallicity-stellar mass relations are found to become shallower in denser environments. This is due to the fact that the average age and metallicity of low mass satellite galaxies increase with the mass of the halo in which they reside. A comparison with the semi-analytical model of Wang et a…
The evolution of the metal content of galaxies and its relations to other global properties [such as total stellar mass (M*), circular velocity, star formation rate (SFR), halo mass, etc.] provides important constraints on models of galaxy formation. Here we examine the evolution of metallicity scaling relations of simulated galaxies in the Galaxies-Intergalactic Medium Interaction Calculation suite of cosmological simulations. We make comparisons to observations of the correlation of gas-phase abundances with M* (the mass-metallicity relation, MZR), as well as with both M* and SFR or gas mass…
The heartbeat of stellar halos: Insights from the stellar halo mass-metallicity relation
Pontificia Universidad Católica de Chile（智利天主教 Pontificia 大学）；Universidad de La Serena（拉塞雷纳大学）；CONICET-UBA（阿根廷国家科学研究委员会-布宜诺斯艾利斯大学）；Universidad Autónoma de Madrid（马德里自治大学）
We present a new spectroscopic study of the faint Milky Way satellite Sagittarius II. Using multi-object spectroscopy from the Fibre Large Array Multi Element Spectrograph, we supplement the dataset of Longeard et al. (2020) with 47 newly observed stars, 19 of which are identified as members of the satellite. These additional member stars are used to put tighter constraints on the dynamics and the metallicity properties of the system. We find a low velocity dispersion of SgrII v = 1.7 +/- 0.5 km s-1, in agreement with the dispersion of Milky Way globular clusters of similar luminosity. We conf…
The origin of nebular HeII emission, which is frequently observed in low-metallicity (O/H) star-forming galaxies, remains largely an unsolved question. Using the observed anticorrelation of the integrated X-ray luminosity per unit of star formation rate ($L_X/{\rm SFR}$) of an X-ray binary population with metallicity and other empirical data from the well-studied galaxy I Zw 18, we show that the observed HeII 4686 intensity and its trend with metallicity is naturally reproduced if the bulk of He$^+$ ionizing photons are emitted by the X-ray sources. We also show that a combination of X-ray bin…
Though S0 galaxies are usually thought to be `red and dead', they demonstrate often star formation organized in ring structures. We try to clarify the nature of this phenomenon and its difference from star formation in spiral galaxies. The luminous S0 galaxy with a large ring, UGC 5936, is studied here. By applying long-slit spectroscopy along the major axis of UGC 5936, we have measured gas and star kinematics, Lick indices for the main body of the galaxy, and strong emission-line flux ratios in the ring. After inspecting the gas excitation in the ring using line ratios diagnostic diagrams an…
Within the standard model of hierarchical galaxy formation in a ΛCDM Universe, the environment of galaxies is expected to play a key role in driving galaxy formation and evolution. In this paper we investigate whether and how the gas metallicity and the star formation surface density (Σ_SFR) depend on galaxy environment. To this end we analyse a sample of 1162 local, star-forming galaxies from the galaxy survey Mapping Nearby Galaxies at APO (MaNGA). Generally, both parameters do not show any significant dependence on environment. However, in agreement with previous studies, we find that low-m…
We explore how the star formation and metal enrichment histories of present-day galaxies have been affected by environment combining stellar population parameter estimates and group environment characterization for SDSS DR7. We compare stellar ages, stellar metallicities and element abundance ratios [alpha/Fe] of satellite and central galaxies, as a function of their stellar and host group halo mass, controlling for the current star formation rate and for the infall epoch. We confirm that below log(Mstar/Msun)=10.5 satellites are older and metal-richer than equally-massive central galaxies. On…
We examine the mass-metallicity relation for $z\lesssim 1.6$. The mass-metallicity relation follows a steep slope with a turnover or `knee' at stellar masses around $10^{10} M_\odot$. At stellar masses higher than the characteristic turnover mass, the mass-metallicity relation flattens as metallicities begin to saturate. We show that the redshift evolution of the mass-metallicity relation depends only on evolution of the characteristic turnover mass. The relationship between metallicity and the stellar mass normalized to the characteristic turnover mass is independent of redshift. We find that…
We explore the relative role of small-scale fragmentation and global collapse in low-metallicity clouds, pointing out that in such clouds the cooling time may be longer than the dynamical time, allowing the cloud to collapse globally before it can fragment. This, we suggest, may help to explain the formation of the low-metallicity globular cluster population, since such dense stellar systems need a large amount of gas to be collected in a small region (without significant feedback during the collapse). To explore this further, we carry out numerical simulations of low-metallicity Bonner-Ebert …
We present a detailed study of the faint Milky Way satellite Draco II (Dra II) from deep CFHT/MegaCam broadband $g$ and $i$ photometry and narrow-band metallicity-sensitive CaHK observations, along with follow-up Keck II/DEIMOS multi-object spectroscopy. Forward modeling of the deep photometry allows us to refine the structural and photometric properties of Dra II: the distribution of stars in colour-magnitude space implies Dra II is old (13.5 $ \pm 0.5 $ Gyr), very metal poor, very faint ($ L_V = 180 ^{+124}_{-72} L_\odot $), and at a distance $d = 21.5 \pm 0.4$ kpc. The narrow-band, metallic…
Using hydrodynamical $N$-body simulations, we show that the observed structure and kinematics of the extremely metal-poor, dwarf irregular galaxy DDO 68 is compatible with a merger event with at least two smaller satellite galaxies. We were able to obtain a self-consistent model that simultaneously reproduces several of its observed features, including: the very asymmetric and disturbed shape of the stellar component, the overall HI distribution and its velocity field, the arc-like stellar structure to the west, the low-surface brightness stellar stream to the north. The model implies the inte…
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 investigate how environment affects satellite galaxies using their location within the projected phase-space of their host haloes from the Wang et al.'s group catalogue. Using the Yonsei Zoom in Cluster Simulations, we derive zones of constant mean infall time T_inf in projected phase-space, and catalogue in which zone each observed galaxy falls. Within each zone we compute the mean observed galaxy properties including specific star formation rate, luminosity-weighted age, stellar metallicity and [alpha/Fe] abundance ratio. By comparing galaxies in different zones, we inspect how shifting t…
We investigate the properties of satellite galaxies in cosmological N-body/SPH simulations of galaxy formation in Milky Way-sized haloes. Because of their shallow potential wells, satellite galaxies are very sensitive to heating processes which affect their gas content. Their properties can therefore be used to constrain the nature of feedback processes that regulate galaxy formation. In our simulations, we assume that all the energy produced by supernovae is used as kinetic energy to drive galactic winds. Several of our simulations produce bright, disc-dominated galaxies. We find that wind mo…
We analyze the radial and vertical metallicity and [alpha/Fe] gradients of the disk stars of a disk galaxy simulated in a fully cosmological setting with the chemodynamical galaxy evolution code, GCD+. We study how the radial abundance gradients vary as a function of height above the plane and find that the metallicity ([alpha/Fe]) gradient becomes more positive (negative) with increasing height, changing sign around 1.5 kpc above the plane. At the largest vertical height (2 < |z| < 3 kpc), our simulated galaxy shows a positive radial metallicity gradient. We find that the positive metallicity…
Dynamical Origins of Azimuthal Metallicity Variations in the Galactic Disk: Insights from Kinematic Ridges with Gaia
The University of Texas at Austin（德克萨斯大学奥斯汀分校）；University of Surrey（萨里大学）；Flatiron Institute（平顿研究所）；University of Toronto（多伦多大学）；Princeton University（普林斯顿大学）
As galaxy simulations increase in resolution more attention is being paid towards the evolution of dwarf galaxies and how the simulations compare to observations. Despite this increasing resolution we are however, far away from resolving the interactions of satellite dwarf galaxies and the hot coronae which surround host galaxies. We describe a new method which focuses only on the local region surrounding an infalling dwarf in an effort to understand how the hot baryonic halo will alter the chemodynamical evolution of dwarf galaxies. Using this method we examine how a dwarf, similar to Sextans…
In the local Universe, globular clusters (GCs) with metallicities $[{\rm Fe}/{\rm H}]<-2.5$ are extremely rare. In this Letter, the close connection between GC formation and galaxy evolution is used to show that this GC metallicity `floor' results from the galaxy mass-metallicity relation of ultra low-luminosity galaxies (ULLGs) at high redshift, where the most metal-poor GCs must have formed. Galaxies with metallicities $[{\rm Fe}/{\rm H}]\lesssim-2.5$ have too low masses to form GCs with initial masses $M_{\rm i}\gtrsim10^5~{\rm M}_\odot$, needed to survive for a Hubble time. This translates…
