Jet Launching from Binary Neutron Star Mergers: Incorporating Neutrino Transport and Magnetic Fields

Sun, Lunan; Ruiz, Milton; Shapiro, Stuart L.; Tsokaros, Antonios

doi:10.48550/arxiv.2202.12901

Cited by 5 publications

(6 citation statements)

References 169 publications

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“…In both plots, the solid lines show the Fourier transforms of the full waveforms, while the dashed lines show the Fourier transforms of the post-merger part of the waveforms only. Consistent with findings reported in the literature [100][101][102][103][104][105][106][107][108], the spectra at low (<1 kHz) frequencies are dominated by the inspiral with increasing amplitude up to a maximum at the frequency of the binary at the merger. This feature is absent in the post-merger spectra.…”

Section: Gravitational Wave Emissionsupporting

confidence: 91%

Thinking Outside the Box: Numerical Relativity with Particles

2022

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The observation of gravitational waves from compact objects has now become an active part of observational astronomy. For a sound interpretation, one needs to compare such observations against detailed Numerical Relativity simulations, which are essential tools to explore the dynamics and physics of compact binary mergers. To date, essentially all simulation codes that solve the full set of Einstein’s equations are performed in the framework of Eulerian hydrodynamics. The exception is our recently developed Numerical Relativity code SPHINCS_BSSN which solves the commonly used BSSN formulation of the Einstein equations on a structured mesh and the matter equations via Lagrangian particles. We show here, for the first time, SPHINCS_BSSN neutron star merger simulations with piecewise polytropic approximations to four nuclear matter equations of state. In this set of neutron star merger simulations, we focus on perfectly symmetric binary systems that are irrotational and have 1.3 M⊙ masses. We introduce some further methodological refinements (a new way of steering dissipation, an improved particle–mesh mapping), and we explore the impact of the exponent that enters in the calculation of the thermal pressure contribution. We find that it leaves a noticeable imprint on the gravitational wave amplitude (calculated via both quadrupole approximation and the Ψ4 formalism) and has a noticeable impact on the amount of dynamic ejecta. Consistent with earlier findings, we only find a few times 10−3M⊙ as dynamic ejecta in the studied equal mass binary systems, with softer equations of state (which are more prone to shock formation) ejecting larger amounts of matter. In all of the cases, we see a credible high-velocity (∼0.5…0.7c) ejecta component of ∼10−4M⊙ that is launched at contact from the interface between the two neutron stars. Such a high-velocity component has been suggested to produce an early, blue precursor to the main kilonova emission, and it could also potentially cause a kilonova afterglow.

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Section: Gravitational Wave Emissionsupporting

confidence: 91%

Thinking Outside the Box: Numerical Relativity with Particles

2022

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show abstract

“…In both plots, the solid lines show the Fourier transforms of the full waveforms, while the dashed lines show the Fourier transforms of the post merger part of the waveforms only. Consistent with findings reported in the literature [97][98][99][100][101][102][103][104][105], the spectra at low (< 1 kHz) frequencies are dominated by the insipiral with increasing amplitude up to a maximum at the frequency of the binary at the merger. This feature is absent in the post merger spectra.…”

Section: Gravitational Wave Emissionsupporting

confidence: 91%

Thinking outside the box: Numerical Relativity with particles

Rosswog¹,

Diener²,

Torsello³

2022

Preprint

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The observation of gravitational waves from compact objects has now become an active part of observational astronomy. For a sound interpretation, one needs to compare such observations against detailed Numerical Relativity simulations, which are essential tools to explore the dynamics and physics of compact binary mergers. To date, essentially all simulation codes that solve the full set of Einstein's equations are performed in the framework of Eulerian hydrodynamics. The exception is our recently developed Numerical Relativity code SPHINCS_BSSN which solves the commonly used BSSN formulation of Einstein equations on a structured mesh and the matter equations via Lagrangian particles. We show here, for the first time, SPHINCS_BSSN neutron star merger simulations with piecewise polytropic approximations to four nuclear matter equations of state. We introduce some further methodological refinements (a new way of steering dissipation, an improved particlemesh mapping) and we explore the impact of the exponent that enters in the calculation of the thermal pressure contribution. We find that it leaves a noticeable imprint on the gravitational wave amplitude (calculated via both quadrupole approximation and the Ψ 4 -formalism) and has a noticeable impact on the amount of dynamic ejecta. Consistent with earlier findings, we only find a few times 10 −3 M as dynamic ejecta in the studied equal mass binary systems, with softer equations of state (which are more prone to shock formation) ejecting larger amounts of matter. We also see a credible high-velocity (∼ 0.5..0.7c) ejecta component of ∼ 10 −4 M in all our cases. Such a high-velocity component has been suggested to produce an early, blue precursor to the main kilonova emission and it could also potentially cause a kilonova afterglow.

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“…Unlike the GRMHD equations, however, the system cannot be closed with an EOS, making its accuracy dependent on the choice of closure (see e.g., [44]). This method has also been used in many studies, including core-collapse [45][46][47][48][49][50][51][52][53] and BNS [54][55][56][57][58].…”

Section: Introductionmentioning

confidence: 99%