Ion Heating in Pair-loaded Relativistic Turbulence

Abstract: Pair-loaded relativistic turbulence is expected in compact high-energy astrophysical environments and may sustain plasma heating. Using self-consistent three-dimensional radiative particle-in-cell simulations, we identify the mechanism of ion heating mediated by pair-enhanced radiative feedback in relativistic turbulence. We derive the theoretical criterion for the transition to a regime dominated by radiative feedback and show that pair loading promotes the growth and persistence of large, connected optically thick structures. These long-lived structures sustain intense localized ion heating, repeatedly generating prominent hot-ion clumps and substantially enhancing the mean ion temperature. Our results establish a physical link between pair creation and sustained ion heating, providing a theoretical basis for investigating intermittent hot-ion production in black-hole coronae and gamma-ray burst outflows.