Structure of stable binary neutron star merger remnants: Role of initial spin

W. Kastaun, R. Ciolfi, A. Endrizzi, and B. Giacomazzo
Phys. Rev. D 96, 043019 – Published 30 August 2017
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Abstract

We present general relativistic numerical simulations of binary neutron star (BNS) mergers with different initial spin configurations. We focus on models with stars of mass 1.4M each, which employ the equation of state (EOS) by Shen, Horowitz, and Teige, and which result in stable NSs as merger remnants. For comparison, we consider two irrotational equal mass (M=1.35M) and unequal mass (M=1.29, 1.42M) BNS models using the APR4 EOS, which result in a supramassive merger remnant. We present visualizations of the fluid flow and temperature distribution and find a strong impact of the spin on vortex structure and nonaxisymmetric deformation. We compute the radial mass distribution and the rotation profile in the equatorial plane using recently developed measures independent of spatial gauge, revealing slowly rotating cores that can be well approximated by the cores of spherical stars. We also study the influence of the spin on the inspiral phase and the gravitational wave (GW) signal. Using a newly developed analysis method, we further show that gravitational waveforms from BNS mergers can exhibit one or more phase jumps after merger, which occur together with minima of the strain amplitude. We provide a natural explanation in terms of the remnant’s quadrupole moment, and show that cancellation effects due to phase jumps can have a strong impact on the GW power spectrum. Finally, we discuss the impact of the spin on the amount of ejected matter.

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  • Received 13 December 2016

DOI:https://doi.org/10.1103/PhysRevD.96.043019

© 2017 American Physical Society

Physics Subject Headings (PhySH)

Gravitation, Cosmology & Astrophysics

Authors & Affiliations

W. Kastaun

  • Max Planck Institute for Gravitational Physics (Albert Einstein Institute), Callinstr. 38, 30167 Hannover, Germany
  • Leibniz Universität Hannover, Institute for Gravitational Physics, Callinstr. 38, 30167 Hannover, Germany
  • Physics Department, University of Trento, via Sommarive 14, I-38123 Trento, Italy
  • INFN-TIFPA, Trento Institute for Fundamental Physics and Applications, via Sommarive 14, I-38123 Trento, Italy

R. Ciolfi

  • INAF, Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, I-35122 Padova, Italy
  • INFN-TIFPA, Trento Institute for Fundamental Physics and Applications, via Sommarive 14, I-38123 Trento, Italy
  • Physics Department, University of Trento, via Sommarive 14, I-38123 Trento, Italy

A. Endrizzi

  • Physics Department, University of Trento, via Sommarive 14, I-38123 Trento, Italy
  • INFN-TIFPA, Trento Institute for Fundamental Physics and Applications, via Sommarive 14, I-38123 Trento, Italy

B. Giacomazzo

  • Physics Department, University of Trento, via Sommarive 14, I-38123 Trento, Italy
  • INFN-TIFPA, Trento Institute for Fundamental Physics and Applications, via Sommarive 14, I-38123 Trento, Italy

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Issue

Vol. 96, Iss. 4 — 15 August 2017

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