Gamma-ray burst (GRB) X-ray flares are believed to mark the late time activity of the central engine. I compute the temporal evolution of the average flare luminosity in the common rest frame energy band of 44 GRBs taken from the large Swift 5-years data base. This work highlights the importance of a proper consideration of the threshold of detection of flares against the contemporaneous continuous X-ray emission. In the time interval 30s < t < 1000s the flare luminosity decays as (propor. to) t~(-2.7+-0.1), while the flare isotropic energy decays as E_(iso,flare) (propor. to) t~(-1.7). These results are discussed in the context of GRB hyper-accretion models.
展开▼
