The Eiso-Liso Plane for Gamma-Ray Bursts

Abstract

Gamma-ray bursts (GRBs) are the most intense and powerful explosions in the universe. Based on their observed duration, they are traditionally divided into long bursts whose observed duration equals or exceeds 2 s, and short bursts whose observed duration is less than 2 s. Several GRB energy and luminosity correlations have been discovered for long gamma-ray bursts. Two important correlations are the Amati relation and the Yonetoku relation. The Amati relation is a correlation between the intrinsic peak energy, Ep,i, obtained from the νFν spectrum and the equivalent isotropic energy, Eiso, while the Yonetoku relation is a correlation between Ep,i and the peak isotropic luminosity, Liso. In this paper, we use a recent data sample that includes both long and short GRBs to compare these two correlations for the two groups of bursts. We also compare the Eiso-Liso plane for these two types of bursts. Our results indicate that both long and short bursts adhere to these two correlations but with different normalizations. We also find that the Eiso-Liso plane is similar for both types of GRBs but is shifted to lower values of Eiso for short GRBs.