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arXiv · 2412.16280

Electrodynamics and dissipation in the binary magnetosphere of pre-merger neutron stars

Jens F. Mahlmann·Andrei M. Beloborodov
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Abstract

We investigate 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 $\chi_1$ and $\chi_2$ of the stars' magnetic dipole moments relative to their orbital angular momentum. The simplest aligned configuration ($\chi_1=\chi_2=0^\circ$) 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 Alfv\'enic 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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Jens F. Mahlmann, Andrei M. Beloborodov. 2024-12-20. Electrodynamics and dissipation in the binary magnetosphere of pre-merger neutron stars. https://doi.org/10.3847/2041-8213%2Fadb5fd

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