Discovery of Interacting Molecular Gas toward the TeV Gamma-Ray Peak of the SNR G 347.3--0.5
Takahashi, Tadayuki; Uchiyama, Yasunobu; Fukui, Yasuo; Onishi, Toshikazu; Tawara, Yuzuru; Tamura, Keisuke; Yamamoto, Hiroaki; Mizuno, Norikazu; Moriguchi, Yoshiaki; Mizuno, Akira; Hiraga, Junko; Yamashita, Koujin; Ikeuchi, Satoru
Japan, France
Abstract
Supernova remnants ( = SNR) are suggested to be sites of cosmic-ray acceleration. In particular, it has been an issue of keen interest whether cosmic ray protons are being accelerated in a SNR which emits TeV γ-rays. A crucial observational test for this is to find dense molecular gas towards the SNR, because such molecular gas can best verify the existence of cosmic-ray protons via pion decay to γ-rays. Here, we show that new high-resolution mm-wave observations of interstellar CO molecule have revealed molecular gas at 1kpc distance interacting with the TeV γ-ray SNR G 347.3 - 0.5, and that a molecular cloud of ∼ 200 solar masses is clearly associated with the TeV γ-ray peak, providing strong evidence for proton acceleration. We have estimated the total energy of accelerated protons to be ∼ 1048 erg, which corresponds to an acceleration efficiency of ∼ 0.001, posing an observational constraint on the proton acceleration.