BATSE data support the multicomponent model for Gamma Ray Bursts prompt emission

Abstract

Observations of the prompt emission of several Gamma Ray Bursts (GRBs) detected with the instruments on-board the Fermi Gamma ray Space Telescope (hereafter Fermi) as well with the Burst and Transient Source Experiment (BATSE) on-board the Compton Gamma Ray Observatory (CGRO) reveal deviations from the Band function to describe their spectra in the keV-MeV energy range. Analysis of Fermi data conclude that GRB prompt emission is adequately fitted with the simultaneous combination of three emission components: a thermal-like component interpreted as the jet photosphere, a non-thermal component interpreted as synchrotron radiation from particles within the jet and an additional non-thermal power-law (PL) function extending from low to high energies in gamma-rays, interpreted as Inverse Compton emission. In this work we present new analysis of three BATSE Bursts, namely GRBs 941017, 970111 and 990123. We show that the BATSE data are fully consistent with the model derived from Fermi data and that these three BATSE bursts also exhibit the three different components as reported from Fermi, noticing that they present similar spectral behaviour. In addition, the analysis using this three-component model during the prompt emission results in a strong correlation between the time-resolved luminosity and the corresponding rest-frame F spectral peak energy (LnTh i -EnTh;rest p;i relation). When fitted with a power law the relation have similar indices for all three bursts and these values are also in perfect agreement with the Fermi results. This points toward a possible universal emission process intrinsic to the non-thermal component of GRB prompt emission. Using this correlation we estimated the redshift for GRBs 941017 and 970111 using GRB990123 (with known redshift) as reference. The estimated redshifts for these bursts are typical values for long GRBs.