Magnetosphere Evolution and Precursor-Driven Electromagnetic Signals in Merging Binary Neutron Stars
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| Format: | Preprint |
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2025
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| author | Skiathas, Dimitrios Kalapotharakos, Constantinos Wadiasingh, Zorawar Kazanas, Demosthenes Harding, Alice K. Kolbeck, Paul T. |
| author_facet | Skiathas, Dimitrios Kalapotharakos, Constantinos Wadiasingh, Zorawar Kazanas, Demosthenes Harding, Alice K. Kolbeck, Paul T. |
| contents | We detail new force-free simulations to investigate magnetosphere evolution and precursor electromagnetic (EM) signals from binary neutron stars. Our simulations fully follow a representative inspiral motion, capturing the intricate magnetospheric dynamics and their impact on EM outflows. We explore a range of stellar magnetic moment orientations and relative strengths, finding that the magnetospheres and Poynting flux evolution are strongly configuration-dependent. The Poynting flux exhibits pulsations at twice the orbital frequency, $2Ω$, and is highly anisotropic, following a power-law dependence on orbital frequency. The index ranges from 1 to 6, shaped by the intricate dynamics of the magnetospheres. Furthermore, we present the first computation of: (1) The EM forces acting on the star surfaces, revealing the presence of torques that, for highly-magnetized stars, could influence the orbital dynamics or break the crust. (2) The high-energy emission signals from these systems by adopting the established isolated pulsar theory. Assuming curvature radiation in the radiation reaction limit, we find that photons could reach TeV--PeV energies in the last $\sim$~ms for magnetic field strengths $10^{10}-10^{15}$~G. However, our analysis of single photon magnetic pair production suggests that these photons are unlikely to escape, with the MeV band emerging as a promising observational window for precursor high-energy emission. In this framework, we construct high-energy emission skymaps and light curves, exploring observational implications. Finally, we propose potential precursor radio emission and delayed afterglow echoes from magnetized outflows, which may contribute to late-time re-brightening in short gamma-ray bursts or to orphan afterglows. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2503_19884 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Magnetosphere Evolution and Precursor-Driven Electromagnetic Signals in Merging Binary Neutron Stars Skiathas, Dimitrios Kalapotharakos, Constantinos Wadiasingh, Zorawar Kazanas, Demosthenes Harding, Alice K. Kolbeck, Paul T. High Energy Astrophysical Phenomena We detail new force-free simulations to investigate magnetosphere evolution and precursor electromagnetic (EM) signals from binary neutron stars. Our simulations fully follow a representative inspiral motion, capturing the intricate magnetospheric dynamics and their impact on EM outflows. We explore a range of stellar magnetic moment orientations and relative strengths, finding that the magnetospheres and Poynting flux evolution are strongly configuration-dependent. The Poynting flux exhibits pulsations at twice the orbital frequency, $2Ω$, and is highly anisotropic, following a power-law dependence on orbital frequency. The index ranges from 1 to 6, shaped by the intricate dynamics of the magnetospheres. Furthermore, we present the first computation of: (1) The EM forces acting on the star surfaces, revealing the presence of torques that, for highly-magnetized stars, could influence the orbital dynamics or break the crust. (2) The high-energy emission signals from these systems by adopting the established isolated pulsar theory. Assuming curvature radiation in the radiation reaction limit, we find that photons could reach TeV--PeV energies in the last $\sim$~ms for magnetic field strengths $10^{10}-10^{15}$~G. However, our analysis of single photon magnetic pair production suggests that these photons are unlikely to escape, with the MeV band emerging as a promising observational window for precursor high-energy emission. In this framework, we construct high-energy emission skymaps and light curves, exploring observational implications. Finally, we propose potential precursor radio emission and delayed afterglow echoes from magnetized outflows, which may contribute to late-time re-brightening in short gamma-ray bursts or to orphan afterglows. |
| title | Magnetosphere Evolution and Precursor-Driven Electromagnetic Signals in Merging Binary Neutron Stars |
| topic | High Energy Astrophysical Phenomena |
| url | https://arxiv.org/abs/2503.19884 |