Fermi Gamma-ray Space Telescope

Gamma rays from radiative SNRs

Abdul Asvarov

Abstract:

In this presentation we have considered Gamma-ray emission from supernova remnants (SNRs) evolving in high density environments, for which the radiative phase of evolution is unavoidable. Gamma-rays from such objects are believed to have hadronic origin, i.e. as a result of decay of neutral $pi^{0}$-mesons, created in the p-p collisions of relativistic hadrons (protons, etc.) with interstellar medium protons. Diffusive shock acceleration (DSA) mechanism is considered as the main mechanism of acceleration of relativistic particles. We assume that SNR evolves in more or less homogeneous interstellar medium. For the largest value of the gamma-ray luminosity of the SNR with initial energy of SN explosion $E_{rm SN}$ evolving in the ISM with particles density $n_{0}$ we obtain the relation: $ L_{gamma} (>100 rm {MeV})propto textit{n}_{0}^{13/17}cdot textit{E}_{rm {SN}}^{19/17}$. Radiative SNRs with high initial energy or/and evolving in high density ISM may be the best candidates for the unidentified gamma-sources in the Fermi catalogs.