Fully kinetic simulations of plasma accretion in a three-dimensional shearing box

Charlista: Prof. Fabio Bacchini, KU Leuven

Resumen: One of the main uncertainties in the physics of plasma accretion onto compact objects (black holes and neutron stars) is represented by the dynamics of microscopic processes at kinetic scales. Although often expected to be collisionless, accretion flows around black holes are customarily studied with magnetohydrodynamic (MHD) models; these models however do not include out-of-equilibrium physics and cannot describe nonthermal particle acceleration and radiation, particle scattering and diffusion, and the transport of angular momentum through astrophysical accretion disks.

To study these processes self-consistently, fully kinetic simulations are necessary; but the prohibitive costs typically associated to such numerical experiments have so far inhibited significant progress in this direction.

In this talk, we will present the mesoscale (i.e. attaining global MHD-like behavior) simulations of plasma accretion carried out with a fully kinetic approach in three dimensions. Our work is based on the shearing-box paradigm, which allows the first-principles study of a localized sector of an accretion disk at affordable costs. Our 3D kinetic simulations are large enough to reach convergence (with respect to physical parameters and box size), allowing us to analyze the detail of particle acceleration and angular-momentum transport in the turbulent plasma dynamics developing in a typical collisionless accretion flow.