Electrodynamics and Dissipation in the Binary Magnetosphere of Premerger Neutron Stars

We investigate the energy release in the interacting magnetospheres of binary neutron stars (BNSs) with global 3D force-free electrodynamics simulations. The system dynamics depend on the inclinations χ _1 and χ _2 of the stars’ magnetic dipole moments relative to their orbital angular momentum. The...

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Main Authors: Jens F. Mahlmann, Andrei M. Beloborodov
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:The Astrophysical Journal Letters
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Online Access:https://doi.org/10.3847/2041-8213/adb5fd
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author Jens F. Mahlmann
Andrei M. Beloborodov
author_facet Jens F. Mahlmann
Andrei M. Beloborodov
author_sort Jens F. Mahlmann
collection DOAJ
description We investigate the energy release in the interacting magnetospheres of binary neutron stars (BNSs) with global 3D force-free electrodynamics simulations. The system dynamics depend on the inclinations χ _1 and χ _2 of the stars’ magnetic dipole moments relative to their orbital angular momentum. The simplest aligned configuration ( χ _1  =  χ _2  = 0 ^∘ ) has no magnetic field lines connecting the two stars. Remarkably, it still develops separatrix current sheets warping around each star and a dissipative region at the interface of the two magnetospheres. A Kelvin–Helmholtz (KH)–type instability drives significant dissipation at the magnetospheric interface, generating local Alfvénic turbulence and escaping fast magnetosonic waves. Binaries with inclined magnetospheres release energy in two ways: via KH instability at the interface and via magnetic reconnection flares in the twisted flux bundles connecting the companions. Outgoing compressive waves occur in a broad range of BNS parameters, possibly developing shocks and sourcing fast radio bursts. We discuss implications for X-ray and radio precursors of BNS mergers.
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spelling doaj-art-2c730ff21d43493b85624092d7dadfcb2025-08-20T02:11:05ZengIOP PublishingThe Astrophysical Journal Letters2041-82052025-01-019811L1710.3847/2041-8213/adb5fdElectrodynamics and Dissipation in the Binary Magnetosphere of Premerger Neutron StarsJens F. Mahlmann0https://orcid.org/0000-0002-5349-7116Andrei M. Beloborodov1https://orcid.org/0000-0001-5660-3175Department of Astronomy & Astrophysics, Pupin Hall, Columbia University , New York, NY 10027, USA ; jens.mahlmann@columbia.edu; Department of Physics & Astronomy, Wilder Laboratory, Dartmouth College , Hanover, NH 03755, USADepartment of Physics, Pupin Hall, Columbia University , New York, NY 10027, USA; Max Planck Institute for Astrophysics , Garching, 85741, GermanyWe investigate the energy release in the interacting magnetospheres of binary neutron stars (BNSs) with global 3D force-free electrodynamics simulations. The system dynamics depend on the inclinations χ _1 and χ _2 of the stars’ magnetic dipole moments relative to their orbital angular momentum. The simplest aligned configuration ( χ _1  =  χ _2  = 0 ^∘ ) has no magnetic field lines connecting the two stars. Remarkably, it still develops separatrix current sheets warping around each star and a dissipative region at the interface of the two magnetospheres. A Kelvin–Helmholtz (KH)–type instability drives significant dissipation at the magnetospheric interface, generating local Alfvénic turbulence and escaping fast magnetosonic waves. Binaries with inclined magnetospheres release energy in two ways: via KH instability at the interface and via magnetic reconnection flares in the twisted flux bundles connecting the companions. Outgoing compressive waves occur in a broad range of BNS parameters, possibly developing shocks and sourcing fast radio bursts. We discuss implications for X-ray and radio precursors of BNS mergers.https://doi.org/10.3847/2041-8213/adb5fdBinary pulsarsMagnetic fieldsRadiative processesPlasma astrophysicsMagnetohydrodynamical simulations
spellingShingle Jens F. Mahlmann
Andrei M. Beloborodov
Electrodynamics and Dissipation in the Binary Magnetosphere of Premerger Neutron Stars
The Astrophysical Journal Letters
Binary pulsars
Magnetic fields
Radiative processes
Plasma astrophysics
Magnetohydrodynamical simulations
title Electrodynamics and Dissipation in the Binary Magnetosphere of Premerger Neutron Stars
title_full Electrodynamics and Dissipation in the Binary Magnetosphere of Premerger Neutron Stars
title_fullStr Electrodynamics and Dissipation in the Binary Magnetosphere of Premerger Neutron Stars
title_full_unstemmed Electrodynamics and Dissipation in the Binary Magnetosphere of Premerger Neutron Stars
title_short Electrodynamics and Dissipation in the Binary Magnetosphere of Premerger Neutron Stars
title_sort electrodynamics and dissipation in the binary magnetosphere of premerger neutron stars
topic Binary pulsars
Magnetic fields
Radiative processes
Plasma astrophysics
Magnetohydrodynamical simulations
url https://doi.org/10.3847/2041-8213/adb5fd
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