X-Ray Destruction of Dust along the Line of Sight to γ-Ray Bursts

We show that if all γ-ray bursts emit X-rays in a way similar to those observed by BeppoSAX, much of the extinction along the line of sight in the host galaxy of the burst can be destroyed. Two mechanisms are principally responsible for dust destruction: grain heating and grain charging. The latter, which can lead to electrostatic stresses greater than the tensile strength of the grains, is often the more important. Grains may regularly be destroyed at distances as large as ~100 pc. This dust destruction can permit us to see the UV/optical afterglow even when the burst is embedded deep within a highly obscured region. Because the destruction rate depends on grain composition and size, it may be possible to observe the amount and wavelength dependence of extinction change during the course of the burst and first few minutes of the afterglow. It may also be possible to detect interstellar absorption lines in the afterglow spectrum that would not exist but for the return of heavy elements to the gas phase.