Numerical evolution of secular bar-mode instability induced by the gravitational radiation reaction in rapidly rotating neutron stars

Masaru Shibata, Sigeyuki Karino
2004 Physical Review D  
The evolution of a nonaxisymmetric bar-mode perturbation of rapidly rotating stars due to a secular instability induced by gravitational wave emission is studied in post-Newtonian simulations taking into account gravitational radiation reaction. A polytropic equation of state with the polytropic index $n=1$ is adopted. The ratio of the rotational kinetic energy to the gravitational potential energy $T/|W|$ is chosen in the range between 0.2 and 0.26. Numerical simulations were performed until
more » ... e performed until the perturbation grows to the nonlinear regime, and illustrate that the outcome after the secular instability sets in is an ellipsoidal star of a moderately large ellipticity $\agt 0.7$. A rapidly rotating protoneutron star may form such an ellipsoid, which is a candidate for strong emitter of gravitational waves for ground-based laser interferometric detectors. A possibility that effects of magnetic fields neglected in this work may modify the growth of the secular instability is also mentioned.
doi:10.1103/physrevd.70.084022 fatcat:b53ftlgpavcd7nwle3q7bisc4e