Constraints on Lorentz Invariance Violation from PeV Gamma Rays of Cygnus X-3 Observed by LHAASO

Abstract

The Large High Altitude Air Shower Observatory (LHAASO) has detected photons with energies up to 3.7 PeV from the binary system Cygnus X-3 during a flaring episode. The combination of such extreme photon energies and the large source distance provides a sensitive probe of Lorentz invariance violation (LIV). In superluminal LIV scenarios, high-energy photons can become unstable and rapidly decay, resulting in a sharp spectral cutoff. However, the observed hard intrinsic spectrum of Cygnus X-3 exhibits no evidence for such a feature. This absence enables us to place stringent constraints on LIV, with the second-order LIV energy scale constrained to be above 10^{-2}M_{pl}, improving previous limits by nearly an order of magnitude.

arXiv comment12 pages, 4+5 figures