Young, Star-forming Galaxies and their local Counterparts: the Evolving Relationship of Mass-SFR-Metallicity since z ~ 2.1

TL;DR

This study investigates how the relationship between stellar mass, star formation rate, and metallicity in galaxies has evolved from redshift ~2.1 to the present, revealing mass-dependent differences in chemical enrichment.

Contribution

It provides the first detailed comparison of the mass-SFR-metallicity relation at z ~ 2.1 with local galaxies, highlighting evolutionary differences across galaxy masses.

Findings

High-mass, high-SFR galaxies at z ~ 2.1 have higher metallicity than local counterparts.

Low-mass, low-SFR galaxies at z ~ 2.1 have lower metallicity than local counterparts.

The evolution of the relation is mass-dependent, indicating different growth histories.

Abstract

We explore the evolution of the Stellar Mass-Star Formation Rate-Metallicity Relation using a set of 256 COSMOS and GOODS galaxies in the redshift range 1.90 < z < 2.35. We present the galaxies' rest-frame optical emission-line fluxes derived from IR-grism spectroscopy with the Hubble Space Telescope and combine these data with star formation rates and stellar masses obtained from deep, multi-wavelength (rest-frame UV to IR) photometry. We then compare these measurements to those for a local sample of galaxies carefully matched in stellar mass (7.5 < log(M*/Msol) < 10.5) and star formation rate (-0.5 < log(SFR) < 2.5 in Msol yr^-1). We find that the distribution of z ~ 2.1 galaxies in stellar mass-SFR-metallicity space is clearly different from that derived for our sample of similarly bright (L_H\b{eta} > 3 . 10^40 ergs s^-1) local galaxies, and this offset cannot be explained by simple systematic offsets in the derived quantities. At stellar masses above ~10^9 Msol and star formation rates above ~10 Msol yr^-1, the z ~ 2.1 galaxies have higher oxygen abundances than their local counterparts, while the opposite is true for lower-mass, lower-SFR systems.