2025/01/08 by Abigail Moran, Moran, Abigail, Lorenzo Sironi +9 · 1 citation
Earth and Planetary Sciences · Physics and Astronomy · #Atomic and Molecular Physics #FOS: Physical sciences #High Energy Astrophysical Phenomena (astro-ph.HE) #High-pressure geophysics and materials #Laser-Plasma Interactions and Diagnostics
paper · pdf · doi:10.48550/arxiv.2501.04800
openalex publication_date 2025/01/08 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
A variety of high-energy astrophysical phenomena are powered by the release -- via magnetic reconnection -- of the energy stored in oppositely directed fields. Single-fluid resistive magnetohydrodynamic (MHD) simulations with uniform resistivity yield dissipation rates that are much lower (by nearly one order of magnitude) than equivalent kinetic calculations. Reconnection-driven phenomena could be accordingly modeled in resistive MHD employing a non-uniform, ``effective'' resistivity informed by kinetic calculations. In this work, we analyze a suite of fully kinetic particle-in-cell (PIC) simulations of relativistic pair-plasma reconnection -- where the magnetic energy is greater than the rest mass energy -- for different strengths of the guide field orthogonal to the alternating component. We extract an empirical prescription for the effective resistivity, ηeff = αB0 |J|p / (|J|p+1+(e nt c)p+1), where B0 is the reconnecting magnetic field strength, \bf J is the current density, nt the lab-frame total number density, e the elementary charge, and c the speed of light. The guide field dependence is encoded in α and p, which we fit to PIC data. This resistivity formulation -- which relies only on single-fluid MHD quantities -- successfully reproduces the spatial structure and strength of nonideal electric fields, and thus provides a promising strategy for enhancing the reconnection rate in resistive MHD simulations.