Rotational properties of hypermassive neutron stars from binary mergers
Abstract
Determining the differentialrotation law of compact stellar objects produced in binary neutron stars mergers or corecollapse supernovae is an old problem in relativistic astrophysics. Addressing this problem is important because it impacts directly on the maximum mass these objects can attain and, hence, on the threshold to blackhole formation under realistic conditions. Using the results from a large number of numerical simulations in full general relativity of binary neutron star mergers described with various equations of state and masses, we study the rotational properties of the resulting hypermassive neutron stars. We find that the angularvelocity distribution shows only a modest dependence on the equation of state, thus exhibiting the traits of "quasiuniversality" found in other aspects of compact stars, both isolated and in binary systems. The distributions are characterized by an almost uniformly rotating core and a "disk." Such a configuration is significantly different from the j constant differentialrotation law that is commonly adopted in equilibrium models of differentially rotating stars. Furthermore, the restmass contained in such a disk can be quite large, ranging from ≃0.03 M_{☉} in the case of highmass binaries with stiff equations of state, up to ≃0.2 M_{☉} for lowmass binaries with soft equations of state. We comment on the astrophysical implications of our findings and on the longterm evolutionary scenarios that can be conjectured on the basis of our simulations.
 Publication:

Physical Review D
 Pub Date:
 August 2017
 DOI:
 10.1103/PhysRevD.96.043004
 arXiv:
 arXiv:1611.07152
 Bibcode:
 2017PhRvD..96d3004H
 Keywords:

 General Relativity and Quantum Cosmology;
 Astrophysics  High Energy Astrophysical Phenomena
 EPrint:
 25 pages, 20 figures