Ultra High Energy Cosmic Rays from Tidal Disruption Events

Abstract: The tidal disruption event AT2018hyz was a regular optically detected one with no special prompt features. However, it suddenly displayed a fast-rising radio flare almost three years after the disruption. The flare is most naturally interpreted as arising from an off-axis relativistic jet. We didn't see the jet at early times as its emission was relativistically beamed away from us. However, we could see the radiation once the jet has slowed down due to interaction with the surrounding matter. Analysis of the radio data enabled estimates of the jet's kinetic energy and opening angle, as well as the conditions (size and magnetic field) within the radio-emitting region. We show here that such a jet satisfies the Hillas condition for the acceleration of UHECRs to the highest energies. We also show that the rate and total power of this event are consistent with the observed luminosity density of UHECRs. These results strongly support earlier suggestions that TDEs are the sources of UHECRs.