Time-dependent high-energy gamma-ray signal from accelerated particles in core-collapse supernovae: the case of SN 1993J
ABSTRACT Some core-collapse supernovae are likely to be efficient cosmic ray accelerators up to the PeV range, and therefore, to potentially play an important role in the overall Galactic cosmic ray population. The TeV gamma-ray domain can be used to study particle acceleration in the multi-TeV and PeV range. This motivates the study of the detectability of such supernovae by current and future gamma-ray facilities. The gamma-ray emission of core-collapse supernovae strongly depends on the level of the two-photon annihilation process: high-energy gamma-ray photons emitted at the expanding shock wave following the supernova explosion can interact with soft photons from the supernova photosphere through the pair production channel, thereby strongly suppressing the flux of gamma-rays leaving the system. In the case of SN 1993J, whose photospheric and shock-related parameters are well measured, we calculate the temporal evolution of the expected gamma-ray attenuation by accounting for the temporal and geometrical effects. We find the attenuation to be of about 10 orders of magnitude in the first few days after the supernova explosion. The probability of detection of a supernova similar to SN 1993J with the Cherenkov Telescope Array is highest if observations are performed either earlier than 1 d, or later than 10 d after more »
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Award ID(s):
Publication Date:
NSF-PAR ID:
10158339
Journal Name:
Monthly Notices of the Royal Astronomical Society
Volume:
494
Issue:
2
Page Range or eLocation-ID:
2760 to 2765
ISSN:
0035-8711
Supernova remnants (SNRs) are known to accelerate cosmic rays from the detection of non-thermal emission in radio waves, X-rays, and gamma-rays. However, the ability to accelerate cosmic rays up to PeV energies has yet to be demonstrated. The presence of cut-offs in the gamma-ray spectra of several young SNRs led to the idea that PeV energies might only be achieved during the first years of a remnant’s evolution. We use our time-dependent acceleration-code RATPaC to study the acceleration of cosmic rays in supernovae expanding into dense environments around massive stars. We performed spherically symmetric one-dimensional (1D) simulations in which we simultaneously solve the transport equations for cosmic rays, magnetic turbulence, and the hydrodynamical flow of the thermal plasma in the test-particle limit. We investigated typical circumstellar-medium (CSM) parameters expected around red supergiant (RSG) and luminous blue variable (LBV) stars for freely expanding winds and accounted for the strong γγ absorption in the first days after explosion. The maximum achievable particle energy is limited to below $600\,$TeV even for the largest considered values of the magnetic field and mass-loss rates. The maximum energy is not expected to surpass $\approx 200\,$ and $\approx 70\,$TeV for LBVs and RSGs that experience moderate mass-lossmore »