Magneto-Hydrodynamic Simulations of Eccentric Binary Neutron Star Mergers

Fuente: arXiv
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Main Authors: Neuweiler, Anna, Dietrich, Tim, Brügmann, Bernd
Format: Preprint
Published: 2025
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author Neuweiler, Anna
Dietrich, Tim
Brügmann, Bernd
author_facet Neuweiler, Anna
Dietrich, Tim
Brügmann, Bernd
contents Highly eccentric binary neutron star mergers exhibit unique dynamical and observational signatures compared to quasi-circular ones in terms of their gravitational wave signal and the ejection of matter, leading to different electromagnetic counterparts. In this article, we present general relativistic magneto-hydrodynamic simulations of binary neutron star systems on highly eccentric orbits. While in quasi-circular binaries, the influence of the magnetic field is too weak to affect the general pre-merger dynamics, the close encounters in eccentric systems could potentially trigger magneto-hydrodynamic instabilities. Therefore, we investigate possible effects before, during, and after the merger for a total of three different systems with varying initial eccentricity. We study the f-mode oscillations excited by tidal interaction in close encounters and find good agreement with predicted f-mode frequency estimates. However, our simulations reveal no significant differences compared to results neglecting the magnetic field. Although we observe a rearrangement of the poloidal structure of the magnetic field inside the stars, there is no relevant increase in the magnetic energy during the encounters. Also, during the merger, the amplification of the magnetic field seems to be largely independent of the eccentricity in our systems. Consistent with studies of merging non-magnetized binary neutron stars, we find a correlation between eccentricity and mass ejection, with a higher impact parameter leading to a larger amount of unbound material.
format Preprint
id arxiv_https___arxiv_org_abs_2504_10228
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Magneto-Hydrodynamic Simulations of Eccentric Binary Neutron Star Mergers
Neuweiler, Anna
Dietrich, Tim
Brügmann, Bernd
General Relativity and Quantum Cosmology
High Energy Astrophysical Phenomena
Highly eccentric binary neutron star mergers exhibit unique dynamical and observational signatures compared to quasi-circular ones in terms of their gravitational wave signal and the ejection of matter, leading to different electromagnetic counterparts. In this article, we present general relativistic magneto-hydrodynamic simulations of binary neutron star systems on highly eccentric orbits. While in quasi-circular binaries, the influence of the magnetic field is too weak to affect the general pre-merger dynamics, the close encounters in eccentric systems could potentially trigger magneto-hydrodynamic instabilities. Therefore, we investigate possible effects before, during, and after the merger for a total of three different systems with varying initial eccentricity. We study the f-mode oscillations excited by tidal interaction in close encounters and find good agreement with predicted f-mode frequency estimates. However, our simulations reveal no significant differences compared to results neglecting the magnetic field. Although we observe a rearrangement of the poloidal structure of the magnetic field inside the stars, there is no relevant increase in the magnetic energy during the encounters. Also, during the merger, the amplification of the magnetic field seems to be largely independent of the eccentricity in our systems. Consistent with studies of merging non-magnetized binary neutron stars, we find a correlation between eccentricity and mass ejection, with a higher impact parameter leading to a larger amount of unbound material.
title Magneto-Hydrodynamic Simulations of Eccentric Binary Neutron Star Mergers
topic General Relativity and Quantum Cosmology
High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2504.10228