The metallicity properties of long-GRB hosts

TL;DR

This paper uses the Fundamental Metallicity Relation to analyze long-GRB host galaxies, revealing that their metallicity is consistent with their high star formation rates, challenging the idea they prefer low-metallicity environments.

Contribution

It demonstrates that long-GRB hosts follow the FMR, indicating their metallicity is linked to their mass and SFR, and not solely low metallicity.

Findings

GRB hosts have lower metallicity than typical galaxies of the same mass.

GRB hosts are consistent with the FMR, showing metallicity depends on SFR.

Optical afterglow GRBs do not prefer low-metallicity hosts.

Abstract

The recently-discovered Fundamental Metallicity Relation (FMR), which is the tight dependence of metallicity on both mass and SFR, proves to be a very useful tool to study the metallicity properties of various classes of galaxies. We have used the FMR to study the galaxies hosting long-GRBs. While the GRB hosts have lower metallicities than typical galaxies of the same mass, i.e., they are below the mass-metallicity relation, they are fully consistent with the FMR. This shows that the difference with the mass-metallicity relation is due to higher than average SFRs, and that GRBs with optical afterglows do not preferentially select low-metallicity hosts among the star-forming galaxies.