Competitive subluminal LIV limits from ultra-high energy astrophysics

In this contribution, we introduce subluminal Lorentz invariance violation (LIV) in the propagation of ultra-high energy photons. The energy threshold and the mean free path for the pair production considering LIV are calculated. The influence of the models for the sources of ultrahigh energy cosmic rays in the flux of GZK photons is discussed. The resulting fluxes for several sources models and LIV scenarios are obtained and compared to the upper limits on the photon flux from the Pierre Auger Observatory. Updated limits on the LIV coefficient of the order of δ_γ,0 ≳ -10^-20, δ_γ,1 ≳ -10^-38 eV and δ_γ,2 ≳ -10^-56 eV² are imposed for the reference case. The possibility of testing superluminal LIV effects is also discussed.