A High-Metallicity Host Environment for the Long-Duration GRB 020819

TL;DR

This study reports the highest metallicity measured for a long-duration gamma-ray burst host galaxy, challenging existing models of GRB progenitors and exploring its implications for dark burst characteristics.

Contribution

It provides the first detailed spectroscopic metallicity measurement of GRB 020819's host, the highest for such events, and discusses its impact on progenitor theories.

Findings

Host galaxy metallicity is log(O/H)+12=9.0 +/- 0.1.

GRB 020819's high metallicity contrasts with typical long-GRB hosts.

High metallicity may explain the burst's optical darkness.

Abstract

We present spectroscopic observations of the host galaxy and explosion site of the long-duration gamma-ray burst GRB 020819. We determine a metallicity for this host environment of log(O/H) + 12 = 9.0 +/- 0.1, by far the highest metallicity determined for a long-duration GRB to date. We compare the metallicity and other properties of the GRB 020819 host environment to existing observations of long-duration GRB host galaxies, and consider the implications that this metallicity has for our understanding of long-duration GRB progenitor scenarios. We also consider how this unusually high metallicity may relate to the status of GRB 020819 as a "dark" burst, with no detected optical afterglow.