Presentation #101.02 in the session Galaxy Clusters/Large Scale Structures.
Some young supernova remnants exhibit thin filaments of synchrotron radiation coinciding with the forward shock. The two main models accounting for the formation of these filaments differ in their prediction of the narrowing, or not, of the filaments with increasing photon energy. In this presentation, we will describe our observation of such a narrowing of the synchrotron filaments in Cassiopeia A, and how it could help understanding the mechanisms at stake in their formation. We used a new blind source separation method, the pGMCA, on the 1Ms Chandra observation of Cassiopeia A, in order to obtain detailed and unpolluted images of the synchrotron emission around three energy bands. We then extracted the profiles of some duly chosen filaments at the forward shock and at the reverse shock, and fitted them with descriptive models, to estimate and compare their widths. Thus, we were able to assert that there is indeed a narrowing with energy of the synchrotron filaments both at the forward and at the reverse shocks in Cassiopeia A. The energy dependency of this narrowing seems stronger at high energy, which is indicative of a damping effect, confirmed by radio observations.