Abstract
The existence of a “knee” at energy in the cosmic-ray spectrum suggests the presence of Galactic PeV proton accelerators called “PeVatrons.” Supernova remnant (SNR) is a prime candidate for one of these. The recent detection of very high energy (0.1–100 TeV) gamma rays from may be explained either by the decay of neutral pions or inverse Compton scattering by relativistic electrons. We report an analysis of 12 years of Fermi-LAT gamma-ray data that shows that the GeV-TeV gamma-ray spectrum is much harder and requires a different total electron energy than the radio and x-ray spectra, suggesting it has a distinct, hadronic origin. The nondetection of gamma rays below 10 GeV implies additional constraints on the relativistic electron spectrum. A hadronic interpretation of the observed gamma rays is strongly supported. This observation confirms the long-sought connection between Galactic PeVatrons and SNRs. Moreover, it suggests that could be the brightest member of a new population of SNRs whose gamma-ray energy flux peaks at TeV energies. Such a population may contribute to the cosmic-ray knee and be revealed by future very high energy gamma-ray detectors.
- Received 22 December 2021
- Revised 8 March 2022
- Accepted 1 July 2022
DOI:https://doi.org/10.1103/PhysRevLett.129.071101
© 2022 American Physical Society
Physics Subject Headings (PhySH)
synopsis
Identifying a Galactic Particle Accelerator
Published 10 August 2022
An analysis of 12 years of gamma-ray observations has allowed researchers to pinpoint a Galactic source of high-energy cosmic rays.
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