X-ray spectroscopy can provide vital information about the progenitors and environments of supernova remnants. Plasma diagnostics and spectral modelling can be used to infer the energy of the remnant, the density and composition of the surrounding medium, and the degree of equilibrium in the shock heated gas. A new generation of X-ray spectrometers, the first of which was the Broad-Band X-Ray Telescope (BBXRT), has improved our ability to make precise measurements of X-ray line fluxes and energies. We summarize the results obtained from the BBXRT mission. These include a definitive measurement of the Fe K line centroid in the Tycho remnant, production of the first narrow-band X-ray maps (of Puppis A) and the first measurement of an electron-ion equipartition timescales in evolved remnants.

Introduction

Supernova remnants may be grouped into three broad categories, based on their X-ray and radio morphologies. The first of these shows shell-like structure in both bands. The X-rays from these are thermal, arising from the shock heating of ejecta and interstellar material. Prominent examples of this class of remnant are Tycho and the Cygnus Loop. The second category shows centrally peaked emission in both bands; these are the plerions, or Crab-like remnants, after the class archetype. The X-ray emission is a non-thermal power law, dominated by synchrotron processes from the energetic electrons produced by the pulsar. A third category combines elements of the previous two.