Radiation Processes

Abstract

AbstractLike for almost all distant astrophysical objects, our primary knowledge of supernova remnants comes from detecting the radiation they emit. Supernova remnants are true multiwavelength sources, with all parts of the electromagnetic spectrum providing important information on their various properties. Broadly speaking one can divide the radiation from supernova remnants in thermal and non-thermal emission. The thermal emission originates from the electrons and ions that have been shock-heated by either the blast wave or the reverse shock, and the electron energy distribution is Maxwellian. However, supernova remnants shocks also accelerate charged particles to an energy distribution that over large energy ranges can be approximated by a power-law distribution. These accelerated particles are responsible for the non-thermal emission, which in the past was almost synonymous for (radio) synchrotron radiation from relativistic electrons moving in a (weakly) magnetic field. In young supernova remnants and pulsar wind nebulae synchrotron radiation is detectable from the low frequency radio band to X-rays. Traditionally, most supernova remnants have been discovered through their radio synchrotron emission.