Search and analysis of dust-scattered X-ray halos around GRBs

摘要

X-ray halos are often observed around bright Galactic X-ray sources due to the scattering by dust grains. In case of extremely variable sources, like GRBs, they are visible as X-ray expanding rings. Up to now, this phenomenon has been observed during the follow-up observations of four GRBs with XMM-Newton and Swift. The analysis of these data has allowed us to derive accurate distances for the dust clouds and to constrain the prompt GRB emission in the soft X-ray range. We present a new analysis method to study dust scattering expanding rings around GRBs, that we have applied to all the available XMM-Newton and Swift/XRT GRB observations. In particular, we report the results of our analysis of the most recently discovered case: GRB 061019.