Collisionless magnetorotational turbulence in electron-ion plasmas

The magnetorotational instability (MRI) is a fundamental process occurring in astrophysical accretion disks. The MRI promotes accretion by driving turbulence on macroscopic scales. In the process, magnetic reconnection and other collective plasma phenomena can accelerate particles to high (possibly nonthermal) energies. The resulting plasma emission may be measurable with observational campaigns.

In radiatively inefficient accretion flows, plasmas are expected to be collisionless, with ions and electrons at different temperatures. This physical state may be promoted by MRI-driven reconnection and turbulence, which could cause differential heating between the two species. However, the dynamics of the collisionless MRI has been hardly ever explored in electron-ion plasmas.

With large-scale Particle-in-Cell simulations including the electron kinetic physics, we investigate the nonlinear development of the collisionless MRI in electron-ion plasmas. We find qualitative differences with previous pair-plasma studies. We investigate the turbulent stresses and effective viscosity arising during the MRI evolution, the differential heating affecting the two particles species, and the subsequent nonthermal particle acceleration and radiative signatures.