TY - JOUR

T1 - Numerical inside view of hypermassive remnant models for GW170817

AU - Kastaun, W.

AU - Ohme, F.

N1 - Funding Information: This work was supported by the Max Planck Society’s Independent Research Group Program. The numerical simulations and renderings were performed on the Holodeck cluster at the Max Planck Institute for Gravitational Physics, Hanover. The authors thank Tim Dietrich, Riccardo Ciolfi, and the anonymous referee for helpful comments on the manuscript.

PY - 2021/7/15

Y1 - 2021/7/15

N2 - The first multimessenger observation attributed to a merging neutron star binary provided an enormous amount of observational data. Unlocking the full potential of this data requires a better understanding of the merger process and the early postmergcr phase, which arc crucial for the later evolution that eventually leads to observable counterparts. In this work, we perform standard hydrodynamical numerical simulations of a system compatible with GW170817. We focus on a single equation of state and two mass ratios, while neglecting magnetic fields and neutrino radiation. We then apply newly developed postprocessing and visualization techniques to the results obtained for this basic setting. The focus lies on understanding the three-dimensional structure of the remnant, most notably the fluid flow pattern, and its evolution until collapse. We investigate the evolution of mass and angular momentum distribution up to collapse, as well as the differential rotation along and perpendicular to the equatorial plane. For the cases that we studied, the remnant cannot be adequately modeled as a differentially rotating axisymetric neutron star. Further, the dominant aspect leading to collapse is the gravitational wave radiation and not internal redistribution of angular momentum. We relate features of the gravitational wave signal to the evolution of the merger remnant and make the waveforms publicly available. Finally, we find that the three-dimensional vorticity field inside the disk is dominated by medium-scale disturbances and not the orbital velocity, with potential consequences for magnetic field amplification effects.

AB - The first multimessenger observation attributed to a merging neutron star binary provided an enormous amount of observational data. Unlocking the full potential of this data requires a better understanding of the merger process and the early postmergcr phase, which arc crucial for the later evolution that eventually leads to observable counterparts. In this work, we perform standard hydrodynamical numerical simulations of a system compatible with GW170817. We focus on a single equation of state and two mass ratios, while neglecting magnetic fields and neutrino radiation. We then apply newly developed postprocessing and visualization techniques to the results obtained for this basic setting. The focus lies on understanding the three-dimensional structure of the remnant, most notably the fluid flow pattern, and its evolution until collapse. We investigate the evolution of mass and angular momentum distribution up to collapse, as well as the differential rotation along and perpendicular to the equatorial plane. For the cases that we studied, the remnant cannot be adequately modeled as a differentially rotating axisymetric neutron star. Further, the dominant aspect leading to collapse is the gravitational wave radiation and not internal redistribution of angular momentum. We relate features of the gravitational wave signal to the evolution of the merger remnant and make the waveforms publicly available. Finally, we find that the three-dimensional vorticity field inside the disk is dominated by medium-scale disturbances and not the orbital velocity, with potential consequences for magnetic field amplification effects.

UR - http://www.scopus.com/inward/record.url?scp=85109327867&partnerID=8YFLogxK

U2 - 10.48550/arXiv.2103.01586

DO - 10.48550/arXiv.2103.01586

M3 - Article

VL - 104

JO - Physical Review D

JF - Physical Review D

SN - 2470-0010

IS - 2

M1 - 023001

ER -