TeV Cosmic-Ray Nucleus Acceleration in Shell-type Supernova Remnants with Hard γ-Ray Spectra

Abstract The emission mechanism for hard γ -ray spectra from supernova remnants (SNRs) is still a matter of debate. Recent multiwavelength observations the TeV source HESS J1912+101 show that it associated with an SNR age ∼100 kyr, making unlikely produce via leptonic processes. We analyzed Fermi and found extended spectrum. may represent peculiar stage evolution dominates acceleration cosmic rays. By fitting 13 SNRs GeV simple models density ratio electrons to protons ∼10 −2 , we obtain reasonable mean densities magnetic fields total energy 50 erg relativistic ions in each SNR. Among these sources, only two them, namely SN 1006 RCW 86, favor origin emission. field be comparable accelerated their has tendency increase SNRs. These results suggest rays mainly originate spectra.