Joonas Naettilae (Columbia University)

Astrophysical compact objects like neutron stars and accreting black holes are luminous sources of nonthermal radiation. Their activity demonstrates efficient dissipation of macroscopic energy stored in magnetic fields. A possible way for the dissipation can be a macroscopic MHD instability that excites turbulent motions in the tangled magnetic fields which, in turn, enables a transfer of energy to small scales where it can be dissipated. We performed 2D and 3D fully-kinetic radiative simulations of such reconnection-mediated turbulent flares in magnetized weakly-collisional pair plasmas. Turbulence is excited on a macroscopic scale and we observe that it develops by forming thin, dynamic current sheets on various scales. This gives rise to highly variable nonthermal flares whose characteristics we model in detail. Our fully-kinetic simulations can also be used to study the energy transfer mechanism of turbulent cascades themselves since they capture the dissipation processes from first principles.