Reconciling the Metallicity Distributions of Gamma-ray Burst, Damped Lyman-alpha, and Lyman-break Galaxies at z=3

TL;DR

This study compares the metallicity distributions of gamma-ray burst host galaxies, Damped Lyman-alpha systems, and Lyman-break galaxies at z=3, suggesting they originate from similar star-forming galaxy populations and can be modeled with simple relations.

Contribution

It demonstrates that the metallicity distributions of GRB and DLA host galaxies can be explained by simple models linking luminosity, metallicity, and HI sizes, supporting their representativeness of high-z star-forming galaxies.

Findings

GRB and DLA metallicity distributions can be matched with simple models.

These galaxy populations likely provide an unbiased view of z=3 star-forming galaxies.

The models can be tested through luminosity and impact parameter observations.

Abstract

We test the hypothesis that the host galaxies of long-duration gamma-ray bursts (GRBs) as well as quasar-selected damped Lyman-alpha (DLA) systems are drawn from the population of UV-selected star-forming, high-z galaxies (generally referred to as Lyman-break galaxies). Specifically, we compare the metallicity distributions of the GRB and DLA populations to simple models where these galaxies are drawn randomly from the distribution of star-forming galaxies according to their star-formation rate and HI cross-section respectively. We find that it is possible to match both observational distributions assuming very simple and constrained relations between luminosity, metallicity and HI sizes. The simple model can be tested by observing the luminosity distribution of GRB host galaxies and by measuring the luminosity and impact parameters of DLA selected galaxies as a function of metallicity. Our results support the expectation that GRB and DLA samples, in contrast to magnitude limited surveys, provide an almost complete census of z=3 star-forming galaxies that are not heavily dust-obscured.