Speaker
Description
Supernova remnants (SNRs) have been considered as a source of the bulk of Galactic cosmic rays (CR). Recently, some evidence of extended gamma-ray emission have been reported by e.g. LHAASO and H.E.S.S. and this emission often has a high maximum energy, suggesting the existence of particles escaping from acceleration regions of SNRs. Although some analytical works have explained based on the escaped CR, and have calculated the gamma-ray spectrum on the environment with SNR shock interacting with clumps and have shown the spectral hardening, such works have generally not included the CR propagation. Therefore, we revisit a setup similar to the conventional CR propagation calculation, which solved the time evolution of the spatial distribution and spectrum of the accelerated particles of evolving shock and the behavior of the evolution.
In this work, we developed the simulation code that calculates the time evolution of phase-space distribution function of CR spectrum by solving the one-dimensional diffusion-convection equation coupled with analytical solutions for shock dynamics. Our results show that the particle acceleration still increases even after the age of 10kyrs in our models. We also calculated $\pi^0$ gamma-ray emission at various stages of SNR evolution with/without clumps located at shock upstream, and compare them with several observed objects. The results show that the emission from clumps in the vicinity can dominate the total flux and significantly hardens the overall spectrum. To explain the observation data, the existence of clumps can play an important role.
