Particle Acceleration during Magnetorotational Instability in a Collisionless Accretion Disk

TL;DR

This study uses particle-in-cell simulations to explore how magnetorotational instability in collisionless accretion disks accelerates particles through magnetic reconnection, potentially explaining high-energy particles near black holes.

Contribution

It reveals the role of magnetic reconnection in MRI saturation and relativistic particle generation in collisionless accretion disks, a novel insight into particle acceleration mechanisms.

Findings

Magnetic reconnection is crucial for MRI saturation.

MRI induces plasma pressure anisotropy leading to rapid reconnection.

Collisionless accretion disks can produce high-energy particles.

Abstract

Particle acceleration during the magnetorotational instability (MRI) in a collisionless accretion disk was investigated by using a particle-in-cell (PIC) simulation. We discuss the important role that magnetic reconnection plays not only on the saturation of MRI but also on the relativistic particle generation. The plasma pressure anisotropy of $p_{\perp} > p_{\para}$ induced by the action of MRI dynamo leads to rapid growth in magnetic reconnection, resulting in the fast generation of nonthermal particles with a hard power-law spectrum. This efficient particle acceleration mechanism involved in a collisionless accretion disk may be a possible model to explain the origin of high energy particles observed around massive black holes.