Expected Signature For the Lorentz Invariance Violation Effects on γγ Absorption

Y. G. Zheng, S. J. Kang, K. R. Zhu, C. Y. Yang, J. M. Bai

Submitted on 3 November 2022, last revised on 9 November 2022


There are still some important unanswered questions about the unexpected very high energy γ-ray signatures. To help understand the mechanism, focusing on the linear and quadratic perturbation mode for subliminal case, the present paper revisited the expected signature for the Lorentz invariance violation effects on γγ absorption in TeV spectra of Gamma-ray bursts (GRBs). We note that the existence of minimum photon energy threshold for the pair production process leads up to a break energy, which is sensitive to the quantum gravity energy scale. We suggest that energy spectral break in the few tens of TeV is a rough observational diagnostic for the LIV effects. The expected spectra characteristics are applied to a GRB 221009A. The results show that the cosmic opacity with Lorentz invariance violation effects considered here is able to roughly reproduce the observed γ-ray spectra for the source, which enabled us to constrain the lower limit of the linear values of energy scale at EQG,1=3.35×1020 GeV for the linear perturbation and EQG,2=9.19×1013 GeV for the quadratic perturbation. This value corresponds to a break energy Eγ,break,155.95 TeV for the linear and Eγ,break,273.66 TeV for the quadratic in the observed frame respectively.


Comment: Submitted, Comments welcome, 8 pages, 5 figures

Subject: Astrophysics - High Energy Astrophysical Phenomena


Target photon energy threshold for the pair production as a function of the $\gamma$-ray photon energy in the case of the linear perturbation. The black solid line shows the standard case. The other lines indicate the modified threshold, which result from the LIV-modified kinematics, for different values of the quantum gravity energy scale. Marks near the curves represent the quantum gravity energy scale in units of Plank energy. The top panel shows the subluminal case, and the bottom panel shows the superluminal case.