Electromagnetic Cascade Emission from Neutrino-coincident Tidal Disruption Events

The potential association between Tidal Disruption Events and high-energy astrophysical neutrinos implies the acceleration of cosmic rays. These accelerated particles will initiate electromagnetic (EM) cascades spanning from keV to GeV energies via the processes related to neutrino production. We model the EM cascade and neutrino emissions by numerically solving the time-dependent transport equations, and discuss the implications for AT2019dsg and AT2019fdr in the X-ray and γ -ray bands. We show that the γ -ray constraints from Fermi can constrain the size of the radiation zone and the maximum energy of injected protons, and that the corresponding expected neutrino event numbers in follow-up searches are limited to be less than about 0.1. Depending on the efficiency of p γ interactions and the time at which the target photons peak, the X-ray and γ -ray signals can be expected closer to the peak of the optical-ultraviolet luminosity or to the time of the neutrino production.