paper

Constraints on binary neutron star merger product from short GRB observations

arXiv:1511.00753 · doi:10.1103/PhysRevD.93.044065

Abstract

Binary neutron star mergers are strong gravitational wave (GW) sources and the leading candidates to interpret short duration gamma-ray bursts (SGRBs). Under the assumptions that SGRBs are produced by double neutron star mergers and that the X-ray plateau followed by a steep decay as observed in SGRB X-ray light curves marks the collapse of a supra-massive neutron star to a black hole (BH), we use the statistical observational properties of {\em Swift} SGRBs and the mass distribution of Galactic double neutron star systems to place constraints on the neutron star equation of state (EoS) and the properties of the post-merger product. We show that current observations already put following interesting constraints: 1) A neutron star EoS with a maximum mass close to a parameterization of is favored; 2) The fractions for the several outcomes of NS-NS mergers are as follows: prompt BHs, supra-massive NSs that collapse to BHs in a range of delay time scales, and stable NSs that never collapse; 3) The initial spin of the newly born supra-massive NSs should be near the breakup limit (), which is consistent with the merger scenario; 4) The surface magnetic field of the merger products is typically G; 5) The ellipticity of the supra-massive NSs is , so that strong GW radiation is released post the merger; 6) Even though the initial spin energy of the merger product is similar, the final energy output of the merger product that goes into the electromagnetic channel varies in a wide range from several erg to several erg, since a good fraction of spin energy is either released in the form of GW or falls into the black hole as the supra-massive NS collapses.

Accepted for publication in Physics Review D

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