The Redshift Distribution of the TOUGH Survey

Author: Palli Jakobsson

Abstract: We present the redshift results from a VLT FORS/X-shooter program aimed at optimizing the legacy value of the Swift mission: to characterize a homogeneous, X-ray selected, sample of 69 GRB host galaxies. At least 17 new redshifts have been secured, resulting in an approximately 80% (55/69) redshift completion of the sample, making it the most comprehensive in terms of redshift completeness to date. We show the cumulative redshift distribution and derive a conservative, yet small, associated uncertainty. Finally, the fraction of Swift GRBs at high redshift is constrained.