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Takafumi Shimizu, Kuniaki Masai, Katsuji Koyama, Non-Thermal Radio and Gamma-Ray Emissions from a Supernova Remnant by Blast Wave Breaking Out of the Circumstellar Matter, Publications of the Astronomical Society of Japan, Volume 65, Issue 3, 25 June 2013, 69, https://doi.org/10.1093/pasj/65.3.69
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Abstract
We calculated synchrotron radio emission and |$ \gamma $|-ray emission due to bremsstrahlung, inverse-Compton scattering, and |$ \pi ^0$|-decay from the remnant of supernova that exploded in the circumstellar matter (CSM) formed by the progenitor's stellar wind. This sort of situation is a possible origin of mixed-morphology supernova remnants (SNRs), like W 49B, which exhibit recombination-radiation spectra in X-ray emission. We assumed that the CSM of 1.5 |$ M_{\odot}$| exists at 0.07–3 pc away from the supernova in the interstellar medium (ISM) of density 0.016 cm|$ ^{-3}$| . When the blast wave breaks out of the CSM into the ISM, its velocity rapidly increases, and hence particle acceleration is enhanced. The maximum energy of protons reaches |$ \sim$| 1300 TeV just after the break-out with |$ \sim$| 0.5% of the explosion energy. We considered the non-thermal emission from the blast-shocked ISM shell after the break-out. Synchrotron radio flux at 1 GHz is tens of Jy, comparable to that observed from mixed-morphology SNRs. Because of low density, the |$ \gamma $|-ray luminosity is dominated by inverse-Compton scattering, which is higher than the |$ \pi ^0$|-decay luminosity by an order of magnitude. The total |$ \gamma $|-ray luminosity, including bremsstrahlung, is on the order of 10|$ ^{33}$| erg s|$ ^{-1}$| lower than the typical value of 10|$ ^{35}$| –10|$ ^{36}$| erg s|$ ^{-1}$| observed from mixed-morphology SNRs. However, if, e.g., |$ \sim$| 10% of accelerated protons interact with some matter of density of |$ \sim$| 100 cm|$ ^{-3}$| , the |$ \pi ^0$|-decay |$ \gamma $|-ray luminosity would be enhanced to be comparable with the observed value.
