Revisiting the Amati and Yonetoku Correlations with Swift GRBs

Abstract

We use a sample of \textit{Swift} gamma-ray bursts (GRBs) to analyze the Amati and Yonetoku correlations. The first relation is between $E_{p,i}$, the intrinsic peak energy of the prompt GRB emission, and $E_{iso}$, the equivalent isotropic energy. The second relation is between $E_{p,i}$ and $L_{iso}$, the isotropic peak luminosity. We select a sample of 71 \textit{Swift} GRBs that have a measured redshift and whose observed $E^{obs}_p$ is within the interval of energy 15-150 keV with a relative uncertainty of less than 70\%. We seek to find correlation relations for long-duration GRBs (LGRBs) with a peak photon flux $P_{ph}\geq 2.6~ \mathrm{ph/cm^{2}/s}$. Uncertainties (error bars) on the values of the calculated energy flux \textit{P}, the energy $E_{iso}$, and the peak isotropic luminosity $L_{iso}$ are estimated using a Monte Carlo approach. We find 27 \textit{Swift} LGRBs that satisfy all our constraints. Results of our analyses of the sample of 71 GRBs and the selected subsample (27 GRBs) are in good agreement with published results. The plots of the two relations for all bursts show a large dispersion around the best straight lines in the sample of 71 LGRBs but not so much in the subsample of 27 GRBs.