Galaxy metallicity scaling relations in the EAGLE simulations

Abstract

Citation for published item:he ossiD w r¡ % imili nd fowerD i h rd qF nd pontD endree F nd h yeD toop nd heunsD om @PHIUA 9q l xy met lli ity s ling rel tions in the ieqvi simul tionsF9D wonthly noti es of the oy l estronomi l o ietyFD RUP @QAF ppF QQSREQQUUF Further information on publisher's website: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. ABSTRACTWe quantify the correlations between gas-phase and stellar metallicities and global properties of galaxies, such as stellar mass, halo mass, age and gas fraction, in the Evolution and Assembly of GaLaxies and their Environments suite of cosmological hydrodynamical simulations. The slope of the correlation between stellar mass and metallicity of star-forming (SF) gas (M * -Z SF,gas relation) depends somewhat on resolution, with the higher resolution run reproducing a steeper slope. This simulation predicts a non-zero metallicity evolution, increasing by ≈0.5 dex at ∼10 9 M since z = 3. The simulated relation between stellar mass, metallicity and star formation rate at z 5 agrees remarkably well with the observed fundamental metallicity relation. At M * 10 10.3 M and fixed stellar mass, higher metallicities are associated with lower specific star formation rates, lower gas fractions and older stellar populations. On the other hand, at higher M * , there is a hint of an inversion of the dependence of metallicity on these parameters. The fundamental parameter that best correlates with the metal content, in the simulations, is the gas fraction. The simulated gas fraction-metallicity relation exhibits small scatter and does not evolve significantly since z = 3. In order to better understand the origin of these correlations, we analyse a set of lower resolution simulations in which feedback parameters are varied. We find that the slope of the simulated M * -Z SF,gas relation is mostly determined by stellar feedback at low stellar masses (M * 10 10 M ), and at high masses (M * 10 10 M ) by the feedback from active galactic nuclei.

The mass–metallicity relations for gas and stars in star-forming galaxies: strong outflow versus variable IMF

“…Using the semi-analytic model L-GALAXIES, combined with a state-of-the-art galactic chemical evolution model, Yates et al (2012) were able to reproduce the MZRgas of local star-forming galaxies but predicted a stellar metallicity significantly higher than the observation. De Rossi et al (2017) found similar results based on a high-resolution cosmological hydrodynamical simulation of EAGLE. Clearly, the challenge is to reproduce the relatively low average stellar metallicity at a given gas metallicity.…”

“…The trend of gas metallicity with stellar mass has been reproduced by semi-analytical galaxy evolution models (e.g., Calura et al 2009;Yates et al 2012) and hydrodynamical simulations (Guo et al 2016;De Rossi et al 2017). However, the MZRstar predicted by these models does not match the observed relation.…”

“…Several flavours of chemical evolution models have been used in the literature to study the origin of the observed MZRs, (such as Thomas et al 1998;Calura et al 2009;Spitoni et al 2017), including combinations with cosmological semianalytical models (Yates et al 2012) or cosmological hydrodynamic simulations (Guo et al 2016;De Rossi et al 2017). Most of the previous chemical evolution models focused on explaining either the gas metallicity or the stellar metallicity of galaxies.…”

Evolution of the Stellar Mass–Metallicity Relation. I. Galaxies in the z ∼ 0.4 Cluster Cl0024

“…These simulations suggest that the stellar MZR evolves monotonically, with an increase in stellar metallicity of ∼0.3 dex at fixed stellar mass from z=1 to z=0. De Rossi et al (2017) presented stellar MZRs at four redshifts derived from a different suite of cosmological hydrodynamical simulations, the Evolution and Assembly of Galaxies and their Environments (EAGLE). The derived stellar MZRs came from a larger number of galaxies than those in Ma et al's (2016) study but with coarser spatial resolution.…”

“…The derived stellar MZRs came from a larger number of galaxies than those in Ma et al's (2016) study but with coarser spatial resolution. De Rossi et al (2017) predicted that the evolution of the stellar MZR is 0.2 dex from z=1 to z=0 at a stellar mass of 10 9.5 M e , slightly smaller than predicted by Ma et al (2016). The classical approach to measuring ages and metallicities of stellar populations is to use spectrophotometric indices such as Lick indices (Faber 1973;Worthey 1994), where the equivalent widths of some spectral features expected to correlate with metal abundance or age are measured and compared to model predictions.…”