A survey of non-thermal shell SNR candidates

The investigation of the general properties of nonthermal Xray shell SNRs, ofwhich SNvirgul1006 is the prototype, is essential to understand how electrons areaccelerated in SNR shocks and in general the origin of cosmic rays.Unfortunately, this class of SNRs is composed by too few members: we thenpropose an XMM large scale program aimed at the discovery of new such objects.We introduce a new selection criterion: the underlying idea is to select SNRsexpanding in a lower density medium, i.e. with a lower thermal Xray emission,that usually outshines the nonthermal one. We have selected the 9 bestcandidates, still not studied or poorly studied in X rays. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]