Behavior of X‐Ray Dust Scattering and Implications for X‐Ray Afterglows of Gamma‐Ray Bursts

Abstract

The afterglows of gamma-ray bursts (GRBs) have commonly been assumed to be\ndue to shocks sweeping up the circum-stellar medium. However, most GRBs have\nbeen found in dense star-forming regions where a significant fraction of the\nprompt X-ray emission can be scattered by dust grains. Here we revisit the\nbehavior of dust scattering of X-rays in GRBs. We find that the features of\nsome X-ray afterglows from minutes to days after the gamma-ray triggers are\nconsistent with the scattering of prompt X-ray emission from GRBs off host dust\ngrains. This implies that some of the observed X-ray afterglows (especially\nthose without sharp rising and decaying flares) could be understood with a\ndust-scattering--driven emission model.\n