Kinetic plasma energization by magnetic Rayleigh-Taylor instability

The magnetic Rayleigh-Taylor instability (RTI) is a fundamental process in many high-energy astrophysical systems, such as pulsar wind nebulae and black-hole accretion flows, caused by an unstable density profile in a gravitational field. In these systems, plasmas are often collisionless and have relativistic components. While the macroscopic RTI dynamics have been well-studied by magnetohydrodynamic models, the kinetic aspects (including particle energization) have not yet been investigated in this regime. We will present results from local kinetic particle-in-cell simulations of the RTI. The simulations consider the unstable equilibrium involving a dense plasma slab on top of a dilute strongly magnetized region, with a magnetic shear across the interface. The ensuing RTI mixes the two plasma domains, driving magnetic reconnection and turbulence. We will describe the dependence of the results on parameters such as the magnetic shear angle, the interface layer thickness, and domain size. The results have implications for black-hole accretion flows, by revealing that the RTI may inject and/or energize a population of nonthermal particles in the disk, explaining observable near-infrared flares.