Speaker
Description
The gamma-ray spectral indexes of SNRs have a bimodal distribution. It has been suggested that the hard gamma-ray spectrum is produced via the inverse Comptonization processes of high-energy electrons in a low-density environment while the soft gamma-ray spectrum is dominated by pion decays produced via inelastic hadronic collisions in a high density region, the so-called leptonic and hadronic scenarios for the gamma-ray emission, respectively. In this paper, we show that SNRs usually evolve in an inhomogeneous environment. For several SNRs, including HESS J1912+101, RX J1713.7-3946, Puppis A, and G150.3+4.5, it is found that the gamma-ray spectrum in the half sphere correlated with molecular clouds or higher density background is softer than the other half-sphere. However, we suggest that this spectral difference is likely caused by the difference in the distribution of emitting particles intrinsic to the particle acceleration process instead of a change of dominance of different emission processes.
