Radio Emission from Supernova Remnants

Abstract

Supernova remnants (SNRs) can radiate their energy across the whole electromagnetic spectrum, but they are principally radio emitters, and investigations in the radio range have provided deep insight into the properties, the evolutionary characteristics, and the physical processes at play. Radio observations permit to delimit the current location of the expanding shock front, to identify sites of particle acceleration, to infer orientation and degree of order of compressed magnetic fields, and to investigate the coupling between the magnetized relativistic wind of the central neutron star and the surrounding plasma. Also, radio observations are a powerful tool to discover new SNRs in our galaxy and in neighboring galaxies. This chapter presents a brief overview of the nature of the radio emission, describing the observable properties that help to constrain theories, i.e., brightness distribution, spectrum, and polarization. The total energy content in a radio remnant is also discussed. In this context, the different morphologies observed in radio remnants and their physical meaning are analyzed. Finally, the problem of linking an SNR with its precursor star and the role of present and future large radio telescopes in the knowledge of SNRs are examined.