Swift gamma – ray bursts consistent with the Ghirlanda relation ?

A few tight correlations linking several properties of gamma–ray bursts (GRBs), namely the spectral peak energy, the total radiated energy, and the afterglow break time, have been discovered with pre-Swift GRBs. They were used to constrain the cosmological parameters together with type-Ia supernovae. However, the tightness of these correlations is a challenge to GRB models. We explore the effect of the addition of Swift bursts to the Ghirlanda and Liang-Zhang relations. Although are still both valid, they become significantly weakened. This is mostly due to the presence of significant outliers, which are otherwise apparently normal GRBs, and thus difficult to discriminate. The increased dispersion of the relations makes them less reliable for precision cosmology purposes.