Nonthermal X‐radiation of SNR RX J1713.7‐3946: The Relations to a Nearby Molecular Cloud

The recent X‐ray and CO observations of RX J1713.7‐3946 show that a significant fraction of the nonthermal X‐ray emission of this unique supernova remnant associates, in one way or another, with a molecular cloud interacting with the west part of the shell. This adds a new puzzle in the origin of X‐ray emission which cannot be easily explained within the standard model in accordance of which X‐rays are result of synchrotron radiation of multi‐TeV electrons accelerated by strong shock waves. We explore an alternative origin of the X‐ray emission assuming that it is produced by secondary‐e^± resulting from high energy hadronic interactions in the molecular gas. Such a scenario could explain in a quite natural way the apparent correlation between the X‐ray and CO morphologies. However, the TeV γ‐ray emission recently reported by H.E.S.S. significantly constraints the parameter space of this model. Namely, this mechanism cannot reproduce the bulk of the observed X‐ray flux unless one postulates existence of a PeV cosmic‐ray component penetrating with an unusually hard spectrum into the dense cloud.