Relativistic reconnection with effective resistivity
Year: 2024
Type: article
Abstract: Context. Relativistic magnetic reconnection is one of the most fundamental mechanisms that is considered responsible for the acceleration of relativistic particles in astrophysical jets and magnetospheres of compact objects. Understanding the properties of the dissipation of magnetic fields and the formation of non-ideal electric fields is of paramount importance to quantify the efficiency of reconnection at energizing charged particles. Aims. Recent results from particle-in-cell (PIC) simulations suggest that the fundamental properties of how magnetic fields dissipate in a current sheet might be captured by an “effective resistivity” formulation, which would locally enhance the amount of magnetic energy dissipated and favor the onset of fast reconnection. Our goal is to assess this ansatz quantitatively by comparing fluid models of magnetic reconnection with a non-constant magnetic diffusivity and fully kinetic models. Methods. We performed 2D resistive relativistic magnetohydrodynamic (ResRMHD) simulations of magnetic reconnection combined to PIC simulations using the same initial conditions (i.e., a Harris current sheet). We explored the impact of crucial parameters such as the plasma magnetization, its mass density, the grid resolution, and the characteristic plasma skin depth. Results. Our ResRMHD models with effective resistivity are able to quantitatively reproduce the dynamics of fully kinetic models of relativistic magnetic reconnection. In particular, they lead to reconnection rates consistent with PIC simulations, whereas for constant-resistivity fluid models, the reconnection dynamics is generally ten times slower. Even at modest resolutions, adopting an effective resistivity can qualitatively capture the properties of kinetic reconnection models and produce reconnection rates compatible with collisionless models (i.e., on the order of ∼10−1).
Source: Astronomy and Astrophysics
Institutions: Centre National de la Recherche Scientifique, Université Paris Cité, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, Université Paris-Saclay, CEA Paris-Saclay - Etablissement de Saclay, Astrophysique, Instrumentation et Modélisation, Istituto Nazionale di Fisica Nucleare, Sezione di Torino, CEA Paris-Saclay, University of Turin, Institut de Planétologie et d'Astrophysique de Grenoble, Université Grenoble Alpes, Max Planck Institute for Astronomy, Istituto Nazionale di Fisica Nucleare, Sezione di Firenze, Arcetri Astrophysical Observatory, University of Florence, National Institute for Astrophysics, Osservatorio Astrofisico di Torino
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $1,732
Awards: G1170389503, G1250998753, Scalable Parallel and distributed Astrophysical Codes for Exascale, Simulating particle acceleration within black hole magnetospheres, G2198355468, G2372493982, G2961278921, G6309823450, General Relativistic numerical models of accretion disks and magnetic reconnection with the PLUTO code
OpenAlex ID: W4405631034