Using gamma-ray bursts to probe the faint, distant galaxy population

Anne Inkenhaag (University of Bath)

Gamma-ray bursts (GRBs) are the most energetic explosions in the universe, often outshining their host galaxies. They have been discovered out to z~9, revealing their host galaxies, which can go undetected in galaxy surveys due to their faintness. We can therefore use GRBs to probe the faintest, most distant galaxies in the universe, and use their imprint on the GRB afterglow to measure properties such as metallicity. Due to the connection between GRBs and massive stars, these measurements are used to expand the star forming galaxy population measured in emission to lower masses and metallicities. However, in this process, two assumptions are made that are highly uncertain: GRB host galaxies follow the same fundamental relations as general star forming galaxies and metallicities measured using GRB afterglows and metallicities measured from integrated galaxy spectra can be used interchangeably. In this talk I will discuss how I am testing the validity of both of these assumptions.