Neutron stars have solid crusts threaded by strong magnetic fields. Perturbations in the crust can excite nonradial oscillations, which can in turn launch Alfvén waves into the magnetosphere. In the case of a compact binary close to merger involving at least one neutron star, this can happen through tidal interactions causing resonant excitations that shatter the neutron star crust. We present the first numerical study that elucidates the dynamics of Alfvén waves launched in a compact binary magnetosphere. We seed a magnetic field perturbation on the neutron star crust, which we then evolve in fully general-relativistic force-free electrodynamics using a GPU-based implementation. We show that Alfvén waves steepen nonlinearly before reaching the orbital light cylinder, form flares, and dissipate energy in a transient current sheet. Our results predict radio and X-ray precursor emission from this process.
Nonlinear Alfvén-wave Dynamics and Premerger Emission from Crustal Oscillations in Neutron Star Mergers
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1.
California Institute of Technology
Abstract
Copyright and License
© 2024. The Author(s). Published by the American Astronomical Society.
Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
Acknowledgement
The authors are grateful for insightful discussions with A. Beloborodov, O. Blaes, A. Bransgrove, D. Neill, A. Philippov, E.S. Phinney, J. Read, B. Ripperda, L. Sironi, A. Suvorov, C. Thompson, Y. Yuan, and B. Zhang. E.R.M. acknowledges support from the National Science Foundation under grant No. AST-2307394. I.L. and K.C. were supported by a grant from the Simons Foundation (MP-SCMPS-00001470). The simulations were performed on DOE NERSC supercomputer Perlmutter under grant m4575. Additional simulations were performed on DOE OLCF Summit under allocation AST198. Preliminary work was also performed on NSF Frontera supercomputer under grant AST21006. E.R.M. further acknowledges the use of Delta at the National Center for Supercomputing Applications (NCSA) through allocation PHY210074 from the Advanced Cyberinfrastructure Coordination Ecosystem: Services and Support (ACCESS) program, which is supported by National Science Foundation grant Nos. 2138259, 2138286, 2138307, 2137603, and 2138296.
Software References
AMReX (W. Zhang et al. 2019), FUKA (L. J. Papenfort et al. 2021), Kadath (P. Grandclement 2010), matplotlib (J. D. Hunter 2007), numpy (C. R. Harris et al. 2020), scipy (P. Virtanen et al. 2020).
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Additional details
- Alternative title
- Nonlinear Alfven-Wave Dynamics and Pre-Merger Emission from Crustal Oscillations in Neutron Star Mergers
- National Science Foundation
- AST-2307394
- Simons Foundation
- MP-SCMPS-00001470
- Accepted
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2024-09-09Accepted
- Available
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2024-09-20Published
- Caltech groups
- Astronomy Department, LIGO, TAPIR, Walter Burke Institute for Theoretical Physics
- Publication Status
- Published