Title: The Observable and Not so Observable Effects of Efficient Diffusive Shock Acceleration on Supernova Remnants
Speaker: Dan Patnaude (CfA)
Abstract: I will present recent results on a study of the nonthermal emission from the Galactic supernova remnant Cassiopeia A. Using recent Chandra observations, we measured the expansion of the blastwave and found that it was less than what is predicted by models for SNR evolution. In order to account for this discrepancy and remain consistent with estimates for the SNR explosion energy and ejecta mass, we argue that ~ 30% of the explosion energy has gone into accelerating cosmic rays at the forward shock. I will also present results from a recent effort to self-consistently model the nonequilibrium ionization and thermal X-ray emission from SNR shocks undergoing efficient diffusive shock acceleration. These new models show that efficient shock acceleration can have a profound and observable effect on the emitted thermal spectrum, and they will provide a powerful new tool in interpreting existing and future observations of SNR shocks.