2011/05/31 by Bruno Giacomazzo, Luciano Rezzolla, Nikolaos Stergioulas · 2 citations
Physics and Astronomy · #Angular momentum #Astrophysical Phenomena and Observations #Astrophysics #Black hole (networking) #Classical mechanics #Cosmic censorship hypothesis #Gamma-ray bursts and supernovae #General relativity #Gravitational collapse #Gravitational singularity #Gravitational wave #Naked singularity #Neutron star #Physics #Pulsars and Gravitational Waves Research #Quantum mechanics #astro-ph.HE #gr-qc
paper · pdf · doi:10.1103/physrevd.84.024022
published as Phys.Rev.D84:024022,2011 · 15 pages, 15 figures. Minor changes to the text and to the references. In press on Phys. Rev. D
arxiv created 2011/07/07 · openalex publication_date 2011/07/13 · arxiv updated 2015/03/18 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We present new results on the dynamics and gravitational-wave emission from the collapse of differentially rotating neutron stars. We have considered a number of polytropic stellar models having different values of the dimensionless angular momentum J/M2, where J and M are the asymptotic angular momentum and mass of the star, respectively. For neutron stars with J/M2<1, i.e. ``sub-Kerr'' models, we were able to find models that are dynamically unstable and that collapse promptly to a rotating black hole. Both the dynamics of the collapse and the consequent emission of gravitational waves resemble those seen for uniformly rotating stars, although with an overall decrease in the efficiency of gravitational-wave emission. For stellar models with J/M2>1, i.e. ``supra-Kerr'' models, on the other hand, we were not able to find models that are dynamically unstable and all of the computed supra-Kerr models were found to be far from the stability threshold. For these models a gravitational collapse is possible only after a very severe and artificial reduction of the pressure, which then leads to a torus developing nonaxisymmetric instabilities and eventually contracting to a stable axisymmetric stellar configuration. While this does not exclude the possibility that a naked singularity can be produced by the collapse of a differentially rotating star, it also suggests that cosmic censorship is not violated and that generic conditions for a supra-Kerr progenitor do not lead to a naked singularity.