Mixed-morphology SNRs are characterized by a shell-like radio emission, a centrally peaked X-ray morphology, and by interaction with molecular clouds. Many models have been proposed to explain these peculiar remnants, but their physical origin is still unclear. The recent discovery of over-ionized (i. e. recombining) ejecta in 3 mixed-morphology SNRs has dramatically challenged all the previous models and opened up new, unexpected scenarios. I review the main properties of these remnants and their peculiar X-ray spectral properties. I also discuss the hydrodynamic model developed to explain the presence of over-ionized ejecta in W49B and present a list of open issues that still need to be clarified.
@article{arxiv.1108.5544,
title = {Overionization in X-ray spectra: a new paradigm for Mixed-Morphology SNRs},
author = {Marco Miceli},
journal= {arXiv preprint arXiv:1108.5544},
year = {2011}
}
Comments
Invited review for Cosmic rays and their interstellar medium environment (CRISM-2011). To be published in a special issue of Memorie della Societa' Astronomica Italiana