A new survey of X-ray flares

One of the most interesting discoveries of the Swift mission is the wide variety of X-ray behaviors observed in the early GRB afterglows. We selected a large sample of bright X-ray flares observed by XRT up to March 2008. The Norris et al. (2005) profile was adopted to characterize the morphological and timing properties of the flares in different energy bands, such as the peak, rise and decay times, the width and the asymmetry of each flare. These parameters were used to estimate other properties in a homogeneous way, such as the temporal lag between the same pulse seen at different energy bands, or the width of the flare as a function of energy, thus allowing us to derive important clues on the underlying physical mechanism and the connections with the central engine.