Kinetic magnetohydrodynamics and Landau fluid closure in relativity

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Hauptverfasser: R., Abhishek Hegade K., Stone, James M.
Format: Preprint
Veröffentlicht: 2026
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author R., Abhishek Hegade K.
Stone, James M.
author_facet R., Abhishek Hegade K.
Stone, James M.
contents Diffuse accretion flows near a supermassive black hole are fundamentally weakly collisional. In such weakly collisional plasmas, the ion and electron distribution functions can deviate significantly from thermal equilibrium, and particle kinetic effects can influence large-scale fluid motion by driving pressure anisotropy, heat conduction, and plasma instabilities. Modeling these plasma effects in highly relativistic flows could be important for interpreting horizon-scale observations of black hole images. In this paper, we present a theoretical framework for understanding weakly collisional plasmas in general relativity by deriving the relativistic drift kinetic equations from the Vlasov-Maxwell equations. We present the evolution equations for the moments of the gyroaveraged distribution function and introduce a new analytic Landau fluid closure to capture anisotropic heat flow in relativistic plasmas. Unlike standard (collisional) general relativistic magnetohydrodynamics or extended magnetohydrodynamics, our model does not rely on strong collisions to enforce thermal equilibrium and consistently incorporates Landau damping in a fluid closure. The model introduced in this work provides a complementary approach to fully kinetic simulations in understanding weakly collisional effects in low-luminosity relativistic black hole accretion disks.
format Preprint
id arxiv_https___arxiv_org_abs_2604_05058
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Kinetic magnetohydrodynamics and Landau fluid closure in relativity
R., Abhishek Hegade K.
Stone, James M.
High Energy Astrophysical Phenomena
General Relativity and Quantum Cosmology
Plasma Physics
Diffuse accretion flows near a supermassive black hole are fundamentally weakly collisional. In such weakly collisional plasmas, the ion and electron distribution functions can deviate significantly from thermal equilibrium, and particle kinetic effects can influence large-scale fluid motion by driving pressure anisotropy, heat conduction, and plasma instabilities. Modeling these plasma effects in highly relativistic flows could be important for interpreting horizon-scale observations of black hole images. In this paper, we present a theoretical framework for understanding weakly collisional plasmas in general relativity by deriving the relativistic drift kinetic equations from the Vlasov-Maxwell equations. We present the evolution equations for the moments of the gyroaveraged distribution function and introduce a new analytic Landau fluid closure to capture anisotropic heat flow in relativistic plasmas. Unlike standard (collisional) general relativistic magnetohydrodynamics or extended magnetohydrodynamics, our model does not rely on strong collisions to enforce thermal equilibrium and consistently incorporates Landau damping in a fluid closure. The model introduced in this work provides a complementary approach to fully kinetic simulations in understanding weakly collisional effects in low-luminosity relativistic black hole accretion disks.
title Kinetic magnetohydrodynamics and Landau fluid closure in relativity
topic High Energy Astrophysical Phenomena
General Relativity and Quantum Cosmology
Plasma Physics
url https://arxiv.org/abs/2604.05058