http://arxiv.org/abs/2012.11531
Supernova remnants (SNRs) have long been considered as one of the most promising sources of Galactic cosmic rays. In the SNR paradigm, acceleration of petaelectronvolt protons may be feasible only at the early evolution stage up to a few hundred years when the SNR shock speed is fast. While evidence supporting the acceleration of PeV protons in young SNRs has yet to be discovered, the nonthermal X-ray emission is an important indicator of fast shock. For middle-aged SNRs, only thermal X-ray emission was detected so far. We here report the first discovery of nonthermal X-ray emission from a middle-aged SNR, namely, SNR~G106.3+2.7, which implies the SNR is still an energetic particle accelerator despite of its age. This discovery along with the ambient environmental information, the multiwavelength observation and theoretical arguments, coherently points to a picture that SNR~G106.3+2.7 is likely a proton PeVatron.
C. Ge, R. Liu, S. Niu, et. al.
Tue, 22 Dec 20
83/89
Comments: 11 pages, 7 figures, 2 tables, submitted to The Innovation