TeV Gamma-Rays from Old Supernova Remnants

Yamazaki Ryo

Kohri Kazunori

Bamba Aya

Yoshida Tatsuo

Tsuribe Toru

Takahara Fumio

Monthly Notices of the Royal Astronomical Society

We study the emission from an old supernova remnant (SNR) with an age of around 105 yrs and that from a giant molecular cloud (GMC) encountered by the SNR. When the SNR age is around 105 yrs, hadron 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 105 yrs, 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. It is found that the ratio of TeV γ-ray (1-10 TeV) to X-ray (2-10 keV) energy flux can be more than ～ 102. Such a source showing large flux ratio may be a possible origin of recently discovered unidentified TeV sources.

acceleration of particles - gamma-rays

theory - ISM

clouds - shock waves - supernova remnants - X-rays

ISM

Astronomy. Space sciences [ 440 ]

eng

Blackwell Publishing Ltd

Copyright (c) 2006 Blackwell Publishing. The definitive version is available at www.blackwell-synergy.com

[ISSN] 0035-8711

[DOI] 10.1111/j.1365-2966.2006.10832.x

[NCID] AA10528285

[DOI] http://dx.doi.org/10.1111/j.1365-2966.2006.10832.x isVersionOf