Alfven-wave turbulence in neutron star and black hole magnetospheres

Relativistic turbulence can illuminate the magnetosphere of astrophysical compact objects, like pulsars, magnetars, neutron star mergers, and black hole accretion flows. This turbulence can be powered by "ringing" of these extreme magnetospheres --- propagation of magnetic shear waves on magnetic field line bundles. These Alfven waves are theoretically known to interact nonlinearly with each other and to produce wave turbulence that can forward cascade the energy from the largest scales to the smallest plasma scales. We use fully-kinetic 3D simulations to study the energization of magnetically-dominated plasmas by this wave turbulence. The turbulence is excited naturally by simulating collisions of large-scale Alfven waves and following their subsequent interaction. We demonstrate that the nonlinear interaction between the waves operates also in the relativistic/magnetically-dominated plasma regime, generates a wave cascade, and is capable of dissipating the magnetic energy of the initial waves. The resulting turbulence is observed to produce quasi-thermal heating that energizes particles only along the magnetic field lines. This can generate synchrotron-silent plasmas that have important implications for radiation signals originating from the compact object magnetospheres.