Properties of long gamma-ray burst host galaxies in cosmological simulations

We use galaxy catalogues constructed by combining high-resolution N-body simulations with semi-analytic models of galaxy formation to study the properties of long gamma-ray burst (LGRB) host galaxies. We assume that LGRBs originate from the death of massive young stars and analyse how results are affected by different metallicity constraints on the progenitor stars. As expected, the host sample with no metallicity restriction on the progenitor stars provides a perfect tracer of the cosmic star formation history. When LGRBs are required to be generated by low-metallicity stars, they trace a decreasing fraction of the cosmic star formation rate at lower redshift, as a consequence of the global increase in metallicity. We study the properties of host galaxies up to high redshift (similar to 9), finding that they typically have low metallicity (Z < 0.5 Z(circle dot)) and that they are small (M < 109 M(circle dot)), bluer and younger than the average galaxy population, in agreement with observational data. They are also less clustered than typical L(*) galaxies in the Universe, and their descendents are massive, red and reside in groups of galaxies with halo mass between 1013 and 1014 M(circle dot).