High redshift gamma-ray bursts

Abstract

The brightest gamma-ray bursts (GRBs) can be seen at very high redshifts, offering a probe of star-formation and galaxy evolution, into the reionization era and beyond. Their bright afterglows pinpoint their host galaxies, however faint, and can give redshifts, metallicity estimates, information on the presence of dust and molecules, and HI column densities. Statistical samples of well-observed GRBs at high redshift may therefore tell us about the evolution of the global star formation rate, chemical enrichment, UV escape fraction and the galaxy luminosity function; all of which are very difficult to establish by conventional searches for galaxies. To date, only a handful of z > 6 GRBs have been discovered, but their presence at z > 8 begins to realise their potential as searchlights to illuminate the early Universe.