Overionization: a new paradigm for Mixed-Morphology SNRs | Marco Miceli ( DiFi-UNIPA )

Mixed-morphology SNRs are characterized by a shell-like radio emission and a centrally peaked X-ray morphology and are all interacting with molecular clouds. Many models have been proposed to explain these peculiar remnants, but their physical origin is still unclear. The recent discovery of overionized (i. e. recombining) ejecta in 3 MM SNRs has dramatically challenged all the previous models and opened up new, unexpected scenarios. I review the main properties of these remnants and present an XMM-Newton observation of W49B together with a hydrodynamic model developed to explain the new results. I also discuss the (long) list of open questions.