Multiple-component spectral analysis of 24 Fermi LAT GRBs and the Eiso-Ei,peak relation

Abstract

The use of correlations between various observable quantities for Gamma-ray bursts (GRBs) has been the subject of much interest and discussion. In particular, many studies have explored the Eiso-Ei,peak relation, its origin and its potential use as a means to discriminate between GRBs from various progenitors. Observations of GRBs through the Fermi Gamma-Ray Space Telescope have also opened up the possibility of studying this correlation over a wide range of energies from keVs to GeVs. While the correlation has been studied through Fermi Large Area Telescope (LAT) GRBs with measured redshifts, its compatibility with LAT GRBs without measured redshifts is yet to be tested. In this paper, we study this correlation with a sample of 24 Fermi LAT GRBs with unknown redshift. We analyze their data between 8 keV and 100 GeV through single and multiple-component spectral models. We use the results of this analysis to study the compatibility of these GRBs with the Eiso-Ei,peak relation by varying the redshift continuously between 0.3 and 10.5. We find that all 24 GRBs are compatible with the Eiso-Ei,peak relation within a 1-sigma uncertainty for a certain redshift range. The range of compatible redshifts found for each GRB remains consistent with observed redshifts for long GRBs.