Gamma Ray Bursts spectral-energy correlations: Recent results

Abstract

The correlations between the rest frame peak of the νFν spectrum of GRBs (Epeak ) and their isotropic energy (Eiso ) or luminosity (Liso ) could have several implications for the understanding of the GRB prompt emission. These correlations are presently founded on the time-averaged spectral properties of a sample of 95 bursts, with measured redshifts, collected by different instruments in the last 13 years (pre-Fermi). One still open issue is wether these correlations have a physical origin or are due to instrumental selection effects. By studying 10 long and 14 short GRBs detected by Fermi we find that a strong time-resolved correlation between Epeak and the luminosity Liso is present within individual GRBs and that it is consistent with the time-integrated correlation. This result is a direct proof of the existence in both short and long GRBs of a similar physical link between the hardness and the luminosity which is not due to instrumental selection effects. The origin of the Epeak - Liso correlation should be searched in the radiation mechanism of the prompt emission. © International Astronomical Union 2011.