Swift Early X-ray Afterglows: 1. Steep Initial Decay & Flares

Before the launch of Swift afterglow observations typically started at least several hours after the prompt GRB. The rapid autonomous slewing capabilities of Swift enable the monitoring of GRB afterglows from as early as tens of seconds after the GRB trigger, and sometimes even while the prompt emission is still going on. While Swift does not detect most GRB afterglows with its UV-optical telescope (UVOT; this will be discussed in a future meeting), It detects the X-ray afterglows for the vast majority of its GRBs, and follows most of them over a large dynamical range in time and in X-ray flux. The early X-ray afterglows observed by Swift contain many new interesting features, including flares, a fast early decay phase, followed by a flat decay phase, before the onset of the "typical" decay that was observed before Swift. In this meeting we will discuss the new observations by Swift, focusing on the early fast decay stage and the X-ray flares (the flat decay phase will be discussed in the next meeting), their possible causes, and implications for the activity of the central source and for the prompt emission mechanism.