Does The Amati Relation For GRBs Depend On The Host Galaxies?

Abstract

One important relation that has been proposed for long Gamma Ray Bursts (GRBs) is the correlation between the photon energy Ep,i at which the νFν spectrum (in the cosmological rest‐frame) of the prompt emission peaks, and Eiso the total radiated energy computed by assuming isotropic emission—the Amati relation [1]. In attempting to characterize GRBs and their host galaxies [2, 3, 4], we have thought it relevant to investigate the extent to which the Amati relation holds for GRBs regardless of their having a (detected) host galaxy and thus independently of the galactic physical medium in which the burst occurs. For this purpose we undertake a comparison between the Amati relation’s parameters for GRBs with host galaxies and for those without known host galaxies. We consider two sample populations of GRBs for which values of Ep,i and Eiso could be obtained (from the literature and/or calculations), data could be plotted, and relation parameters could be inferred. Our results show that differences in the characterizing parameters of the relation are statistically insignificant, allowing us to conclude that the Amati relation is independent of the GRBs’ host galaxies and their physical conditions.