Towards a standard gamma-ray burst: Tight correlations between the prompt and the afterglow plateau phase emission

Abstract

To find out the astrophysical processes responsible for gamma-ray burst (GRB), it is crucial to discover and understand the relations between their observational properties. This work was performed in the GRB rest frames using a sample of 62 long Swift GRBs with known redshifts. Following the earlier analysis of the correlation between afterglow luminosity (L*a) and break time (T*a), we extend it to correlations between the afterglow and the prompt emission GRB physical parameters. We find a tight physical scaling between the mentioned afterglow luminosity L*a and the prompt emission mean luminosity 〈L*p〉45≡Eiso/T*45. The distribution, with the Spearman correlation coefficient reaching 0.95 for the most accurately fitted subsample, scales approximately as L*a∝〈L*p〉0.745. We have also analysed correlations of L*a with several prompt emission parameters, including the isotropic energy Eiso and the peak energy in the νFν spectrum, Epeak. As a result, we obtain significant correlations also between these quantities, discovering that the highest correlated GRB subsample in the afterglow analysis leads also to the highest prompt-afterglow correlations. Such events can be considered to form a sample of standard GRBs for astrophysics and cosmology. © 2011 The Authors Monthly Notices of the Royal Astronomical Society © 2011 RAS.