Ergoregion instability of ultracompact astrophysical objects
Vítor CardosoDepartment of Physics and Astronomy, The University of Mississippi, University, Mississippi 38677-1848, USAPaolo PaniDepartment of Physics and Astronomy, The University of Mississippi, University, Mississippi 38677-1848, USAMariano CadoniDepartment of Physics and Astronomy, The University of Mississippi, University, Mississippi 38677-1848, USAM. CavagliàDepartment of Physics and Astronomy, The University of Mississippi, University, Mississippi 38677-1848, USA
2008en
ABI
Abstract
Most of the properties of black holes can be mimicked by horizonless compact objects such as gravastars and boson stars. We show that these ultracompact objects develop a strong ergoregion instability when rapidly spinning. Instability time scales can be of the order of 0.1 seconds to 1 week for objects with mass $M=1\ensuremath{-}{10}^{6}{M}_{\ensuremath{\bigodot}}$ and angular momentum $J>0.4{M}^{2}$. This provides a strong indication that ultracompact objects with large rotation are black holes. Explosive events due to ergoregion instability have a well-defined gravitational-wave signature. These events could be detected by next-generation gravitational-wave detectors such as Advanced LIGO or LISA.
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