학술논문

A New Covariant Formalism for Kinetic Plasma Simulations in Curved Spacetimes
Document Type
article
Source
The Astrophysical Journal Letters, Vol 959, Iss 1, p L6 (2023)
Subject
Plasma astrophysics
Plasma physics
Accretion
Classical black holes
Black holes
Astrophysics
QB460-466
Language
English
ISSN
2041-8213
2041-8205
Abstract
Low-density plasmas are characterized by a large-scale separation between the gyromotion of particles around local magnetic fields and the macroscopic scales of the system, often making global kinetic simulations computationally intractable. The guiding center formalism has been proposed as a powerful tool to bridge the gap between these scales. Despite its usefulness, the guiding center approach has been formulated successfully only in flat spacetimes, limiting its applicability in astrophysical settings. Here, we present a new covariant formalism that leads to kinetic equations in the guiding center limit that are valid in arbitrary spacetimes. Through a variety of experiments, we demonstrate that our equations capture all known gyrocenter drifts while overcoming one severe limitation imposed on numerical algorithms by the fast timescales of the particle gyromotion. This formalism will enable explorations of a variety of global plasma kinetic phenomena in the curved spacetimes around black holes and neutron stars.