Program: GS-2021B-Q-202

Fast X-ray Transients (FXRTs) are rare soft X-ray events with durations from seconds to hours whose origin is unknown. Of order, 30 have been detected to date. However, very few have secure redshifts and/or detected host galaxy. A decisive determination between the many mechanisms proposed for their origin (tidal disruptions, shock breakouts, neutron star mergers) requires the understanding of their energetics, environments, and rates. Here we propose to increase the sample of FXRTs with known redshift using GMOS spectroscopy observations of transients with identified host galaxies to measure redshifts, star formation rates, and metallicities for the hosts. Meanwhile, for FXRTs without underlying host galaxies, we request GMOS-imaging r-band observations to identify hosts and put photometric constraints in their redshift.