Effective Resistivity in Relativistic Reconnection: A Prescription Based on Fully Kinetic Simulations
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 1 ord...
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2025-01-01
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| Online Access: | https://doi.org/10.3847/2041-8213/ada158 |
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| author | Abigail Moran Lorenzo Sironi Aviad Levis Bart Ripperda Elias R. Most Sebastiaan Selvi |
| author_facet | Abigail Moran Lorenzo Sironi Aviad Levis Bart Ripperda Elias R. Most Sebastiaan Selvi |
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| description | 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 1 order of magnitude) than equivalent kinetic calculations. Reconnection-driven phenomena could be accordingly modeled in resistive MHD employing a nonuniform, “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, ${\eta }_{\mathrm{eff}}=\alpha {B}_{0}| {\boldsymbol{J}}{| }^{p}/\left(| {\boldsymbol{J}}{| }^{p+1}+{\left(e{n}_{t}c\right)}^{p+1}\right)$ , where B _0 is the reconnecting magnetic field strength, J is the current density, n _t is the lab-frame total number density, e is the elementary charge, and c is 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. |
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| institution | Kabale University |
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| publishDate | 2025-01-01 |
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| spelling | doaj-art-7708f2f7af334619b75f3f0eba346e372025-01-10T14:03:49ZengIOP PublishingThe Astrophysical Journal Letters2041-82052025-01-019782L4510.3847/2041-8213/ada158Effective Resistivity in Relativistic Reconnection: A Prescription Based on Fully Kinetic SimulationsAbigail Moran0https://orcid.org/0000-0002-6437-5229Lorenzo Sironi1https://orcid.org/0000-0002-1227-2754Aviad Levis2https://orcid.org/0000-0001-7307-632XBart Ripperda3https://orcid.org/0000-0002-7301-3908Elias R. Most4https://orcid.org/0000-0002-0491-1210Sebastiaan Selvi5https://orcid.org/0000-0001-9508-1234Department of Astronomy, Columbia University , New York, NY 10027, USA ; abigail.moran@columbia.eduDepartment of Astronomy, Columbia University , New York, NY 10027, USA ; abigail.moran@columbia.edu; Center for Computational Astrophysics , Flatiron Institute, 162 Fifth Ave., New York, NY 10010, USADepartment of Computer Science, University of Toronto , Toronto, ON M5S 2E4, Canada; David A. Dunlap Department of Astronomy & Astrophysics, University of Toronto , Toronto, ON M5S 3H4, CanadaDavid A. Dunlap Department of Astronomy & Astrophysics, University of Toronto , Toronto, ON M5S 3H4, Canada; Canadian Institute for Theoretical Astrophysics , 60 St. George St., Toronto, ON M5S 3H8, Canada; Department of Physics, University of Toronto , 60 St. George St., Toronto, ON M5S 1A7, Canada; Perimeter Institute for Theoretical Physics , 31 Caroline St. North, Waterloo, ON N2L 2Y5, CanadaTAPIR , Mailcode 350-17, California Institute of Technology, Pasadena, CA 91125, USA; Walter Burke Institute for Theoretical Physics , California Institute of Technology, Pasadena, CA 91125, USADepartment of Astronomy, Columbia University , New York, NY 10027, USA ; abigail.moran@columbia.eduA 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 1 order of magnitude) than equivalent kinetic calculations. Reconnection-driven phenomena could be accordingly modeled in resistive MHD employing a nonuniform, “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, ${\eta }_{\mathrm{eff}}=\alpha {B}_{0}| {\boldsymbol{J}}{| }^{p}/\left(| {\boldsymbol{J}}{| }^{p+1}+{\left(e{n}_{t}c\right)}^{p+1}\right)$ , where B _0 is the reconnecting magnetic field strength, J is the current density, n _t is the lab-frame total number density, e is the elementary charge, and c is 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.https://doi.org/10.3847/2041-8213/ada158High energy astrophysicsPlasma astrophysicsMagnetic fieldsMagnetohydrodynamics |
| spellingShingle | Abigail Moran Lorenzo Sironi Aviad Levis Bart Ripperda Elias R. Most Sebastiaan Selvi Effective Resistivity in Relativistic Reconnection: A Prescription Based on Fully Kinetic Simulations The Astrophysical Journal Letters High energy astrophysics Plasma astrophysics Magnetic fields Magnetohydrodynamics |
| title | Effective Resistivity in Relativistic Reconnection: A Prescription Based on Fully Kinetic Simulations |
| title_full | Effective Resistivity in Relativistic Reconnection: A Prescription Based on Fully Kinetic Simulations |
| title_fullStr | Effective Resistivity in Relativistic Reconnection: A Prescription Based on Fully Kinetic Simulations |
| title_full_unstemmed | Effective Resistivity in Relativistic Reconnection: A Prescription Based on Fully Kinetic Simulations |
| title_short | Effective Resistivity in Relativistic Reconnection: A Prescription Based on Fully Kinetic Simulations |
| title_sort | effective resistivity in relativistic reconnection a prescription based on fully kinetic simulations |
| topic | High energy astrophysics Plasma astrophysics Magnetic fields Magnetohydrodynamics |
| url | https://doi.org/10.3847/2041-8213/ada158 |
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