Extreme Metallicity Dwarf Galaxies in IllustrisTNG

Abstract

The use of extremely metal-deficient dwarf galaxies (XMDs) as nearby analogs for high-redshift protogalaxies is generating renewed interest due to recent JWST observations studying these protogalaxies. However, the existence of a population of unenriched galaxies at $z\sim 0$ raises fundamental questions about how galaxies with such pristine gas reservoirs could be formed. To address these questions we study XMDs in the IllustrisTNG simulation. We find that XMDs at $z=0$ are not relics of the first galaxies, but dwarf galaxies that experience a dramatic $\sim 0.3$ dex drop in their gas-phase metallicity in the past few Gyr. We investigate possible causes of this drop in metallicity including high gas fractions, outflow efficiency or inflow/outflow rates, unique environments, pristine inflow metallicity, and inflow/SFR interactions. Of these, we find that inflow/outflow interactions, parameterized by the cumulative regional SFR experienced by inflows, has the strongest correlation with dwarf galaxy metallicity and XMD formation. In other words, inefficient gas enrichment during the short time between its accretion from the CGM and the initiation of star formation is the most important cause of XMD formation in the simulation. Observationally, we identify differences in star formation history between XMDs and non-XMDs (with XMDs having significantly decreased star formation rates on $1-5$ Gyr timescales) and differences in galaxy size (with XMDs having a more extended young stellar population) as the primary differences between the two populations. These results highlight the importance of inflow enrichment efficiency as a possible driver of dwarf galaxy metallicities.

18 pages, 28 figures. Accepted by MNRAS

References in corpus (71)

• Galactic Stellar and Substellar Initial Mass Function
• The Origin of the Mass--Metallicity Relation: Insights from 53,000 Star-Forming Galaxies in the SDSS
• Star Formation in the Milky Way and Nearby Galaxies
• E pur si muove: Galiliean-invariant cosmological hydrodynamical simulations on a moving mesh
• Cosmological SPH simulations: A hybrid multi-phase model for star formation
• Simulating Galaxy Formation with the IllustrisTNG Model
• First results from the IllustrisTNG simulations: matter and galaxy clustering
• First results from the IllustrisTNG simulations: the stellar mass content of groups and clusters of galaxies
• First results from the IllustrisTNG simulations: the galaxy color bimodality
• First results from the IllustrisTNG simulations: A tale of two elements -- chemical evolution of magnesium and europium
• Simulating galaxy formation with black hole driven thermal and kinetic feedback
• A fundamental relation between mass, SFR and metallicity in local and high redshift galaxies
• First results from the IllustrisTNG simulations: radio haloes and magnetic fields
• First Results from the TNG50 Simulation: Galactic outflows driven by supernovae and black hole feedback
• A model for cosmological simulations of galaxy formation physics
• First Results from the TNG50 Simulation: The evolution of stellar and gaseous disks across cosmic time
• Gas-regulation of galaxies: the evolution of the cosmic sSFR, the metallicity-mass-SFR relation and the stellar content of haloes
• The merger rate of galaxies in the Illustris Simulation: a comparison with observations and semi-empirical models
• Updated stellar yields from Asymptotic Giant Branch models
• Cosmological Simulations of Intergalactic Medium Enrichment from Galactic Outflows
• Galaxy Zoo Green Peas: Discovery of A Class of Compact Extremely Star-Forming Galaxies
• The Origin and Evolution of the Galaxy Mass-Metallicity Relation
• Galaxy Evolution in Cosmological Simulations with Outflows II: Metallicities and Gas Fractions
• Multi-Element Abundance Measurements from Medium-Resolution Spectra. III. Metallicity Distributions of Milky Way Dwarf Satellite Galaxies
• The Universal Relation of Galactic Chemical Evolution: The Origin of the Mass-Metallicity Relation
• The Role of Stellar Feedback and Dark Matter in the Evolution of Dwarf Galaxies
• The Metallicity of Galaxy Disks: Infall versus Outflow
• Nucleosynthesis in multi-dimensional SNIa explosions
• The Metallicity Evolution of Interacting Galaxies
• The evolution of the mass-metallicity relation in IllustrisTNG
• Gas-Phase Oxygen Gradients in Strongly Interacting Galaxies: I. Early-Stage Interactions
• Ly$\alpha$ profile, dust, and prediction of Ly$\alpha$ escape fraction in Green Pea Galaxies
• A fundamental relation between the metallicity, gas content, and stellar mass of local galaxies
• The role of cold gas and environment on the stellar mass - metallicity relation of nearby galaxies
• First look with JWST spectroscopy: $z\sim 8$ galaxies resemble local analogues
• Metal flows of the circumgalactic medium, and the metal budget in galactic halos
• Following the flow: tracer particles in astrophysical fluid simulations
• The physics of the fundamental metallicity relation
• Taking Care of Business in a Flash: Constraining the Timescale for Low-Mass Satellite Quenching with ELVIS
• The Role of Environment in the Mass-Metallicity Relation
• Deep Hubble Space Telescope/ACS Observations of I Zw 18: a Young Galaxy in Formation
• The mass-metallicity relation in galaxy clusters: the relative importance of cluster membership versus local environment
• Similar star formation rate and metallicity evolution timescales drive the fundamental metallicity relation
• Extremely metal-poor star-forming galaxies. New detections and general morphological and photometric properties
• Galactic Winds in Low-Mass Galaxies
• On the origin of the fundamental metallicity relation and the scatter in galaxy scaling relations
• Systematic search for extremely metal poor galaxies in the Sloan Digital Sky Survey
• The dependence of the galaxy mass-metallicity relation on environment and the implied metallicity of the IGM
• I ZW 18 -- a New Wolf-Rayet Galaxy
• Intense CIV and HeII Emission in z~0 Galaxies: Probing High-Energy Ionizing Photons
• Metallicity inhomogeneities in local star-forming galaxies as sign of recent metal-poor gas accretion
• Extremely Metal-Poor Representatives Explored by the Subaru Survey (EMPRESS). I. A Successful Machine Learning Selection of Metal-Poor Galaxies and the Discovery of a Galaxy with M*<10^6 M_sun and 0.016 Z_sun
• When are extremely metal-deficient galaxies extremely metal-deficient?
• The role of atomic hydrogen in regulating the scatter of the mass-metallicity relation
• I Zw 18 as morphological paradigm for rapidly assembling high-z galaxies
• The Leoncino Dwarf Galaxy: Exploring the Low-Metallicity End of the Luminosity-Metallicity and Mass-Metallcity Relations
• Galactic chemical enrichment with new metallicity dependent yields
• The evolution of galaxy metallicity scaling relations in cosmological hydrodynamical simulations
• A Preview of JWST Metallicity Studies at Cosmic Noon: The First Detection of Auroral [O II] Emission at High Redshift
• How Environment Affects Galaxy Metallicity through Stripping and Formation History: Lessons from the Illustris Simulation
• Chemodynamic evolution of dwarf galaxies in tidal fields
• Local anti-correlation between star-formation rate and gas-phase metallicity in disk galaxies
• Exploring Chemical Homogeneity in Dwarf Galaxies: A VLT-MUSE study of JKB 18
• EMPRESS. VI. Outflows Investigated in Low-Mass Galaxies with $M_{\ast }=10^4-10^7{M}_{\odot }$: Weak Feedback in Low-Mass Galaxies?
• Gas-phase metallicity break radii of star-forming galaxies in IllustrisTNG
• EMPRESS. III. Morphology, Stellar Population, and Dynamics of Extremely Metal Poor Galaxies (EMPGs): Are EMPGs Local Analogs of High-$z$ Young Galaxies?
• HI gas content of SDSS galaxies revealed by ALFALFA: implications for the mass-metallicity relation and the environmental dependence of HI in the local Universe
• The Role of Inner HI Mass in Regulating the Scatter of the Mass-Metallicity Relation
• The influence of the void environment on the ratio of dark matter halo mass to stellar mass in SDSS MaNGA galaxies
• Spatially-resolved properties of the ionized gas in the HII galaxy J084220+115000
• Figuring Out Gas & Galaxies In Enzo (FOGGIE) VIII: Complex and Stochastic Metallicity Gradients at z > 2