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General-relativistic neutrino-radiation magnetohydrodynamics simulation of black hole-neutron star mergers for seconds

Hayashi, K., Fujibayashi, S., Kiuchi, K., Kyutoku, K., Sekiguchi, Y., & Shibata, M. (in preparation). General-relativistic neutrino-radiation magnetohydrodynamics simulation of black hole-neutron star mergers for seconds.

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2111.04621.pdf (Preprint), 11MB
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Creators:
Hayashi, Kota, Author
Fujibayashi, Sho, Author
Kiuchi, Kenta1, Author
Kyutoku, Koutarou, Author
Sekiguchi, Yuichiro, Author
Shibata, Masaru, Author
Affiliations:
1Computational Relativistic Astrophysics, AEI-Golm, MPI for Gravitational Physics, Max Planck Society, ou_2541714

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Free keywords: Astrophysics, High Energy Astrophysical Phenomena, astro-ph.HE,General Relativity and Quantum Cosmology, gr-qc
Abstract: Seconds-long numerical-relativity simulations for black hole-neutron star mergers are performed for the first time to obtain a self-consistent picture of the merger and post-merger evolution processes. To investigate the case that tidal disruption takes place, we choose the initial mass of the black hole to be $5.4M_\odot$ or $8.1M_\odot$ with the dimensionless spin of 0.75. The neutron-star mass is fixed to be $1.35M_\odot$. We find that after the tidal disruption, dynamical mass ejection takes place spending $\lesssim 10\,{\rm ms}$ together with the formation of a massive accretion disk. Subsequently, the magnetic field in the disk is amplified by the magnetic winding and magnetorotational instability, establishing a turbulent state and inducing the angular momentum transport. The post-merger mass ejection by the magnetically-induced viscous effect sets in at $\sim 300$-$500\,{\rm ms}$ after the tidal disruption, at which the neutrino luminosity drops below $\sim 10^{51.5}\,{\rm erg/s}$, and continues for several hundreds ms. A magnetosphere near the rotational axis of the black hole is developed after the matter and magnetic flux fall into the black hole from the accretion disk, and high-intensity Poynting flux generation sets in at a few hundreds ms after the tidal disruption. The intensity of the Poynting flux becomes low after the significant post-merger mass ejection, because the opening angle of the magnetosphere increases. The lifetime for the stage with the strong Poynting flux is $1$-$2\,{\rm s}$, which agrees with the typical duration of short-hard gamma-ray bursts.

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Dates: 2021-11-08
Publication Status: Not specified
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Rev. Type: -
Identifiers: arXiv: 2111.04621
Degree: -

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