1 research outputs found
Simulation of merging binary neutron stars in full general relativity: case
We have performed 3D numerical simulations for merger of equal mass binary
neutron stars in full general relativity. We adopt a -law equation of
state in the form where P, , \varep and
are the pressure, rest mass density, specific internal energy, and the
adiabatic constant with . As initial conditions, we adopt models of
corotational and irrotational binary neutron stars in a quasi-equilibrium state
which are obtained using the conformal flatness approximation for the three
geometry as well as an assumption that a helicoidal Killing vector exists. In
this paper, we pay particular attention to the final product of the
coalescence. We find that the final product depends sensitively on the initial
compactness parameter of the neutron stars : In a merger between sufficiently
compact neutron stars, a black hole is formed in a dynamical timescale. As the
compactness is decreased, the formation timescale becomes longer and longer. It
is also found that a differentially rotating massive neutron star is formed
instead of a black hole for less compact binary cases, in which the rest mass
of each star is less than 70-80% of the maximum allowed mass of a spherical
star. In the case of black hole formation, we roughly evaluate the mass of the
disk around the black hole. For the merger of corotational binaries, a disk of
mass may be formed, where M_* is the total rest mass of the
system. On the other hand, for the merger of irrotational binaries, the disk
mass appears to be very small : < 0.01M_*.Comment: 27 pages, to appear in Phys. Rev.