The Stellar-mass Function of Long Gamma-Ray Burst Host Galaxies

Abstract Long gamma-ray bursts (GRBs) have been discussed as a potential tool to probe the cosmic star formation rate (SFR) for long time. Some studies found an enhancement in GRB relative galaxy-inferred SFR at high redshifts, which indicates that GRBs may not be good tracers of formation. However, these studies, measured any redshift is average over all galaxies epoch. A deep understanding connection between production and environment also needs characterize population host directly. Based on complete sample hosts, we constrain stellar-mass function (SMF) examine evolution population. Our results confirm strong energy (with index ? = 2.47 ? 0.89 + 0.73 ) or density ( ={1.82}_{-0.59}^{+0.22}$?> 1.82 0.59 0.22 needed order account observations. The SMF can well described by Schechter with power-law ? ? ?1.10 break mass M b ,0 4.9 × 10 ? , independent assumed evolutionary effects. This first formulation SMF. observed discrepancy explained evolving