Relativistic hadrons near accreting compact objects: Dynamical and radiative signatures

Ultrarelativistic protons in the vicinity of an accreting compact object lose energy by interacting with the ambient plasma and radiation field. In the process, they may create significant fluxes of gamma rays, electron-positron pairs, neutrinos and neutrons. I outline the processes by which these particles are created, and their ultimate fates. Pairs and gamma rays participate in an electromagnetic pair cascade, which ultimately contributes to (and may dominate the nonthermal radiation output from the compact object. Virtually all of the neutrinos and a significant fraction of the neutrons escape, and may be responsible for observable radiative and dynamical effects originating far from the compact object.