Dust Destruction in a Nonradiative Shock in the Cygnus Loop Supernova Remnant

Abstract

We present 24 μm and 70 μm images of a non‐radiative shock in the Cygnus Loop supernova remnant, obtained with the Multiband Imaging Photometer on board the Spitzer Space Telescope. The observed emission is from dust grains heated in the post‐shock region. The 70 μm to 24 μm flux ratio depends on the dust heating and the dust destruction rates, and thereby it is a sensitive tracer of the gas density and temperature in the shocked plasma. We model the dust emission and grain destruction in the post‐shock flow, and find that the observed 70 μm to 24 μm flux ratios are produced for post‐shock densities, nH∼2.0 cm−3 and electron temperatures of about 0.20 keV. We find that about 35% of the dust has been destroyed in the shock, and that non‐thermal sputtering (i.e. sputtering due to bulk motion of the grains relative to the gas) contributes significantly to the dust destruction.