Shao, L.Dai, Z. G.Mirabal, Nestor2020-09-042020-09-042007-11-23L. Shao, Z. G. Dai and N. Mirabal, Echo Emission from Dust Scattering and X-Ray Afterglows of Gamma-Ray Bursts, ApJ 675 507 (2008), doi: https://doi.org/10.1086/527047https://doi.org/10.1086/527047http://hdl.handle.net/11603/19596We investigate the effect of X-ray echo emission in gamma-ray bursts (GRBs). We find that the echo emission can provide an alternative way of understanding X-ray shallow decays and jet breaks. In particular, a shallow decay followed by a "normal" decay and a further rapid decay of X-ray afterglows can together be explained as being due to the echo from prompt X-ray emission scattered by dust grains in a massive wind bubble around a GRB progenitor. We also introduce an extra temporal break in the X-ray echo emission. By fitting the afterglow light curves, we can measure the locations of the massive wind bubbles, which will bring us closer to finding the mass-loss rate, wind velocity, and age of the progenitors prior to the GRB explosions.25 pagesen-USThis item is likely protected under Title 17 of the U.S. Copyright Law. Unless on a Creative Commons license, for uses protected by Copyright Law, contact the copyright holder or the author.© 2008. The American Astronomical Society. All rights reserved.Text