Open AccessTeV γ‐rays from old supernova remnants
Author(s) -
Yamazaki Ryo,
Kohri Kazunori,
Bamba Aya,
Yoshida Tatsuo,
Tsuribe Toru,
Takahara Fumio
Publication year - 2006
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2006.10832.x
Subject(s) - physics , astrophysics , supernova remnant , supernova , electron , cosmic ray , flux (metallurgy) , radiation , synchrotron radiation , proton , bremsstrahlung , synchrotron , astronomy , nuclear physics , materials science , metallurgy
We study the emission from an old supernova remnant (SNR) with an age of around 10 5 yr and that from a giant molecular cloud (GMC) encountered by the SNR. When the SNR age is around 10 5 yr, proton acceleration is efficient enough to emit TeV γ‐rays both at the shock of the SNR and that in the GMC. The maximum energy of primarily accelerated electrons is so small that TeV γ‐rays and X‐rays are dominated by hadronic processes, π 0 ‐decay and synchrotron radiation from secondary electrons, respectively. However, if the SNR is older than several 10 5 yr, there are few high‐energy particles emitting TeV γ‐rays because of the energy‐loss effect and/or the wave‐damping effect occurring at low‐velocity isothermal shocks. For old SNRs or SNR–GMC interacting systems capable of generating TeV γ‐ray emitting particles, we calculated the ratio of TeV γ‐ray (1–10 TeV) to X‐ray (2–10 keV) energy flux and found that it can be more than ∼10 2 . Such a source showing large flux ratio may be a possible origin of recently discovered unidentified TeV sources.