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We have constructed models that predict the dynamic evolution and infrared (IR) emission of grains behind nonradiative shock waves. We present a self-consistent treatment of the effect of grain destruction and heating on the ionization structure and X-ray emission of the postshock gas. Incorporating thermal sputtering, collisional heating, and deceleration of grains in the postshock flow, we predict the IR and X-ray fluxes from the dusty plasma as a function of swept-up column density.
Heavy elements such as C, O, Mg, S, Si, and Fe are initially depleted from the gas phase but are gradually returned as the grains are destroyed. The injected neutral atoms require some time to ``catch up'' with the ionization state of the ambient gas. The non-equilibrium ionization state and gradient in elemental abundances in the postshock flow produces characteristic X-ray signatures that can be related to the age of the shock and amount of grain destruction. The effects of grain destruction on the X-ray spectra of shock waves are substantial. We will compare model predictions to observations of the Cygnus Loop and Puppis A.
This project is supported by the NASA Astrophysics Data Program under grant NAG5-2453 to the Smithsonian Astrophysical Observatory.
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