Ultraviolet and Optical Insights into Supernova Remnant Shocks

Abstract

Ultraviolet and optical imaging and spectroscopy of shock waves in supernova remnants provide unique insights into several topics of interest to astronomers. For shocks encountering density enhancements in the interstellar medium, these emissions arise in the cooling and recombination zone directly downstream from the shock, and observations can elucidate and/or constrain the kinemat- ics, chemical abundances, and physical characteristics of the material being encountered. Observations of fast collisionless shocks diagnose the physical processes occurring at and near the shock front itself, in particular thermal equilibration and cosmic ray precursors. In the most youthful objects, the composition and kinematics of the supernova ejecta can be sampled directly, providing unique tests of theoretical expectations. Ongoing improvements in modeling, instrumentation, and deeper views of the faintest objects continue to provide new insights into these topics in the optical wavelength range, although the situation for future ultraviolet observations is less optimistic.