Dust Sputtering by Reverse Shocks in Supernova Remnants

Abstract

We consider sputtering of dust grains, believed to be formed in cooling\nsupernovae ejecta, under the influence of reverse shocks. In the regime of\nself-similar evolution of reverse shocks, we can follow the evolution of ejecta\ndensity and temperature analytically as a function of time in different parts\nof the ejecta, and calculate the sputtering rate of graphite and silicate\ngrains embedded in the ejecta as they encounter the reverse shock. Through\nanalytic (1D) calculations, we find that a fraction of dust mass ($\n1\\hbox{--}20$% for silicates and %$\\le 5$% for graphites) can be sputtered by\nreverse shocks, the fraction varying with the grain size distribution and the\nsteepness of the density profile of the ejecta mass. It is expected that many\nmore grains will get sputtered in the region between the forward and reverse\nshocks, so that our analytical results provide a lower limit to the destroyed\nfraction of dust mass.\n