# The Properties of Reconnection Current Sheets in GRMHD Simulations of Radiatively Inefficient Accretion Flows

## TL;DR

This paper investigates the properties of current sheets in GRMHD simulations of black hole accretion flows, highlighting their potential role in particle acceleration, X-ray flares, and the influence of magnetic reconnection in different disk states.

## Contribution

It characterizes the plasma parameters and magnetic guide fields in current sheets within SANE and MAD accretion disks, providing microphysics inputs for reconnection modeling.

## Key findings

- Reconnection sites exhibit plasma beta from 0.1 to 1000 in SANE disks.
- MAD disks show plasma beta from 0.01 to 1000 with stronger guide fields.
- Magnetic energy in reconnection regions can power observed X-ray flares.

## Abstract

Non-ideal MHD effects may play a significant role in determining the dynamics, thermal properties, and observational signatures of radiatively inefficient accretion flows onto black holes. In particular, particle acceleration during magnetic reconnection events may influence black hole spectra and flaring properties. We use representative GRMHD simulations of black hole accretion flows to identify and explore the structures and properties of current sheets as potential sites of magnetic reconnection. In the case of standard and normal (SANE) disks, we find that, in the reconnection sites, the plasma beta ranges from $0.1$ to $1000$, the magnetization ranges from $10^{-4}$ to $1$, and the guide fields are weak compared to the reconnecting fields. In magnetically arrested (MAD) disks, we find typical values for plasma beta from $10^{-2}$ to $10^3$, magnetizations from $10^{-3}$ to $10$, and typically stronger guide fields, with strengths comparable to or greater than the reconnecting fields. These are critical parameters that govern the electron energy distribution resulting from magnetic reconnection and can be used in the context of plasma simulations to provide microphysics inputs to global simulations. We also find that ample magnetic energy is available in the reconnection regions to power the fluence of bright X-ray flares observed from the black hole in the center of the Milky Way.