The interstellar medium in young supernova remnants: key to the production of cosmic X-rays and γ -rays
Abstract
We review recent progress in elucidating the relationship between high-energy radiation and the interstellar medium (ISM) in young supernova remnants (SNRs) with ages of ∼2000 yr, focusing in particular on RX J1713.7−3946 and RCW 86. Both SNRs emit strong nonthermal X-rays and TeV γ -rays, and they contain clumpy distributions of interstellar gas that includes both atomic and molecular hydrogen. We find that shock-cloud interactions provide a viable explanation for the spatial correlation between the X-rays and ISM. In these interactions, the supernova shocks hit the typically pc-scale dense cores, generating a highly turbulent velocity field that amplifies the magnetic field up to 0.1-1 mG. This amplification leads to enhanced nonthermal synchrotron emission around the clumps, whereas the cosmic-ray electrons do not penetrate the clumps. Accordingly, the nonthermal X-rays exhibit a spatial distribution similar to that of the ISM on the pc scale, while they are anticorrelated at sub-pc scales. These results predict that hadronic γ -rays can be emitted from the dense cores, resulting in a spatial correspondence between the γ -rays and the ISM. The current pc-scale resolution of γ -ray observations is too low to resolve this correspondence. Future γ -ray observations with the Cherenkov Telescope Array will be able to resolve the sub-pc-scale γ -ray distribution and provide clues to the origin of these cosmic γ -rays.
- Publication:
-
Astrophysics and Space Science
- Pub Date:
- June 2021
- DOI:
- 10.1007/s10509-021-03960-4
- arXiv:
- arXiv:2106.00708
- Bibcode:
- 2021Ap&SS.366...58S
- Keywords:
-
- Cosmic rays;
- γ -Rays: ISM;
- ISM: clouds;
- ISM: supernova remnants;
- Astrophysics - High Energy Astrophysical Phenomena;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 18 pages, 15 figures, accepted for publication in Astrophysics and Space Science