The Stellar Chemical Abundances of Simulated Massive Galaxies at $z=2$

Abstract

We analyze the stellar abundances of massive galaxies ($\log M_{\ast }/M_{\odot }>10.5$) at $z=2$ in the IllustrisTNG simulation with the goal of guiding the interpretation of current and future observations, particularly from the James Webb Space Telescope. We find that the effective size, $R_e$, of galaxies strongly affects the abundance measurements: both [Mg/H] and [Fe/H] are anti-correlated with $R_e$, while the relative abundance [Mg/Fe] slightly increases with $R_e$. The $\alpha$ enhancement as tracked by [Mg/Fe] traces the formation timescale of a galaxy weakly, and mostly depends on $R_e$. Aperture effects are important: measuring the stellar abundances within 1~kpc instead of within $R_e$ can make a large difference. These results are all due to a nearly universal, steeply declining stellar abundance profile that does not scale with galaxy size -- small galaxies appear metal-rich because their stars live in the inner part of the profile where abundances are high. The slope of this profile is mostly set by the gas-phase abundance profile and not substantially modified by stellar age gradients. The gas-phase abundance profile, in turn, is determined by the strong radial dependence of the gas fraction and star formation efficiency. We develop a simple model to describe the chemical enrichment, in which each radial bin of a galaxy is treated as an independent closed-box system. This model reproduces the gas-phase abundance profile of simulated galaxies, but not the detailed distribution of their stellar abundances, for which gas and/or metal transport are likely needed.

16 pages, 12+2 figures, accepted for publication in MNRAS

References in corpus (27)

• Introducing the Illustris Project: Simulating the coevolution of dark and visible matter in the Universe
• Properties of galaxies reproduced by a hydrodynamic simulation
• Simulating galaxy formation with black hole driven thermal and kinetic feedback
• Introducing the Illustris Project: the evolution of galaxy populations across cosmic time
• Strangulation as the primary mechanism for shutting down star formation in galaxies
• The Origin of the Galaxy Mass-Metallicity Relation and Implications for Galactic Outflows
• The Atlas3D Project - XXX. Star formation histories and stellar population scaling relations of early-type galaxies
• The Metallicity of Galaxy Disks: Infall versus Outflow
• Origin of chemically distinct discs in the Auriga cosmological simulations
• A massive, quiescent, population II galaxy at a redshift of 2.1
• Gas accretion and galactic fountain flows in the Auriga cosmological simulations: angular momentum and metal re-distribution
• Gas-phase metallicity gradients of TNG50 star-forming galaxies
• From 'bathtub' galaxy evolution models to metallicity gradients
• Resolved galaxy scaling relations in the EAGLE simulation: star formation, metallicity and stellar mass on kpc scales
• The origin of the enhanced metallicity of satellite galaxies
• Toward a Better Understanding of Cosmic Chronometers: Stellar Population Properties of Passive Galaxies at Intermediate Redshift
• Elemental Abundances and Ages of $z\sim 0.7$ Quiescent Galaxies on the Mass-Size Plane: Implication for Chemical Enrichment and Star-Formation Quenching
• The mass-metallicity relation at z~1-2 and its dependence on star formation rate
• Resolved Multi-element Stellar Chemical Abundances in the Brightest Quiescent Galaxy at z $\sim$ 2
• The stellar metallicities of massive quiescent galaxies at 1.0 < z < 1.3 from KMOS+VANDELS
• Time Evolution of Galaxy Scaling Relations in Cosmological Simulations
• The evolution of galaxy metallicity scaling relations in cosmological hydrodynamical simulations
• Explaining the scatter in the galaxy mass-metallicity relation with gas flows
• Stellar population properties of individual massive early-type galaxies at 1.4 < z < 2
• The Impact of Outflows driven by Active Galactic Nuclei on Metals in and around Galaxies
• Stellar mass as the "glocal" driver of galaxies' stellar population properties
• On the variation in stellar $\alpha$-enhancements of star-forming galaxies in the EAGLE simulation

Cited by in corpus (1)

• Growing in number, passive in nature: tracing the evolution of the most massive quiescent galaxies since z ~ 0.8 with BOSS and DESI