Host Galaxies of Long Gamma-Ray Bursts

摘要

We describe the current status and recent results from our Swift/VLT legacy survey, a VLT Large Programme aimed at characterizing the host galaxies of a homogeneously selected sub-sample of Swift gamma-ray bursts (GRBs). The immediate goals are to determine the host luminosity function, study the effects of reddening, determine the fraction of Ly(alpha) emitters in the hosts, and obtain redshifts for targets without a reported one. We have defined a very carefully selected sample, obeying strict and well-defined criteria: 68 targets in total. Among the preliminary results is a large optical detection rate, the lack of extremely red objects (only one possible case in the sample), and 10 new GRB redshifts with the mean redshift of the host sample assessed to be approx.> 2.