Discovery of the Ultra-High-Energy gamma-ray source LHAASO J2002+3238 spatially associated with SNR G69.7+1.0

Abstract

The origin of Galactic PeV cosmic rays is still under debate. Shell-type supernova remnants (SNRs) are proposed to be one of the candidate sources of Galactic PeV cosmic rays, but observational evidence is lacking. Here we report LHAASO's detection on a point source J2002+3238 with a significance of 5.8 sigma above 25 TeV and 6.8 sigma above 100 TeV. The spectrum is consistent with a power-law spectrum with no cutoff. Inside the error region of the source, a shell-type SNR G69.7+1.0 is found locating only 0.07 • away from the best-fit location of the source, suggesting a strong association between the UHE gamma-ray source and the SNR. This provides strong evidence on SNRs as possible PeV accelerators.

ICRC 2023 Rapporteur: Status of the Gamma-ray Astronomy field

“…The VHE observations of 𝛾 Cygni [49,51] favor a hadronic origin for the emission although also reaching lower than PeV energies. New sources like LHAASO J2002+3238 is spatially associated with SNR G69.7+1.0 [52] but the origin of the VHE 𝛾-ray emission is unclear whether it is leptonic or hadronic. SNR G150.3+4.5 observed by LHAASO [53] is a SNR with a pulsar at the center for which both leptonic and hadronic scenarios work.…”