Threedimensional relativistic simulations of rotating neutronstar collapse to a Kerr black hole
Abstract
We present a new threedimensional fully generalrelativistic hydrodynamics code using highresolution shockcapturing techniques and a conformal traceless formulation of the Einstein equations. Besides presenting a thorough set of tests which the code passes with very high accuracy, we discuss its application to the study of the gravitational collapse of uniformly rotating neutron stars to Kerr black holes. The initial stellar models are modeled as relativistic polytropes which are either secularly or dynamically unstable and with angular velocities which range from slow rotation to the massshedding limit. We investigate the gravitational collapse by carefully studying not only the dynamics of the matter, but also that of the trapped surfaces, i.e., of both the apparent and event horizons formed during the collapse. The use of these surfaces, together with the dynamical horizon framework, allows for a precise measurement of the blackhole mass and spin. The ability to successfully perform these simulations for sufficiently long times relies on excising a region of the computational domain which includes the singularity and is within the apparent horizon. The dynamics of the collapsing matter is strongly influenced by the initial amount of angular momentum in the progenitor star and, for initial models with sufficiently high angular velocities, the collapse can lead to the formation of an unstable disc in differential rotation. All of the simulations performed with uniformly rotating initial data and a polytropic or idealfluid equation of state show no evidence of shocks or of the presence of matter on stable orbits outside the black hole.
 Publication:

Physical Review D
 Pub Date:
 January 2005
 DOI:
 10.1103/PhysRevD.71.024035
 arXiv:
 arXiv:grqc/0403029
 Bibcode:
 2005PhRvD..71b4035B
 Keywords:

 04.25.Dm;
 04.40.Dg;
 04.70.Bw;
 97.60.Jd;
 Numerical relativity;
 Relativistic stars: structure stability and oscillations;
 Classical black holes;
 Neutron stars;
 General Relativity and Quantum Cosmology;
 Astrophysics
 EPrint:
 28 pages. Animations can be found at http://www.sissa.it/~rezzolla/Whisky/WhiskyI/