Gravitational instabilities of superspinars
Abstract
Superspinars are ultracompact objects whose mass M and angular momentum J violate the Kerr bound (cJ/GM^2>1). Recent studies analyzed the observable consequences of gravitational lensing and accretion around superspinars in astrophysical scenarios. In this paper we investigate the dynamical stability of superspinars to gravitational perturbations, considering either purely reflecting or perfectly absorbing boundary conditions at the "surface" of the superspinar. We find that these objects are unstable independently of the boundary conditions, and that the instability is strongest for relatively small values of the spin. Also, we give a physical interpretation of the various instabilities that we find. Our results (together with the well-known fact that accretion tends to spin superspinars down) imply that superspinars are very unlikely astrophysical alternatives to black holes.
Additional Information
© 2010 The American Physical Society. Received 10 June 2010; published 6 August 2010. It is a pleasure to thank T. Jacobson for helpful discussions on the problems discussed in this paper, as well as C. Bambi for reading an early version of the manuscript and providing useful comments and suggestions. We also thank S. Dolan for sharing with us some preliminary material on the relation between geodesics and linear perturbations in the Kerr spacetime. E. Barausse acknowledges support from NSF Grant No. PHY-0903631. Emanuele Berti's research was supported by the NSF under Grant No. PHY-0900735. V. Cardoso acknowledges financial support from Fundação Calouste Gulbenkian and from a "Ciência 2007" research contract. This work was partially supported by FCT-Portugal through Project Nos. PTDC/FIS/098025/2008, PTDC/FIS/098032/2008, PTDC/CTE-AST/098034/2008, CERN/FP/109306/2009, and CERN/FP/109290/2009.Attached Files
Published - Pani2010p11163Phys_Rev_D.pdf
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Additional details
- Eprint ID
- 19721
- Resolver ID
- CaltechAUTHORS:20100830-150115776
- PHY-0903631
- NSF
- PHY-0900735
- NSF
- Fundação Calouste Gulbenkian
- PTDC/FIS/098025/2008
- Fundação para a Ciência e a Tecnologia (FCT)
- PTDC/FIS/098032/2008
- Fundação para a Ciência e a Tecnologia (FCT)
- PTDC/CTE-AST/098034/2008
- Fundação para a Ciência e a Tecnologia (FCT)
- CERN/FP/109306/2009
- Fundação para a Ciência e a Tecnologia (FCT)
- CERN/FP/109290/2009
- Fundação para a Ciência e a Tecnologia (FCT)
- Created
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2010-09-01Created from EPrint's datestamp field
- Updated
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2021-11-08Created from EPrint's last_modified field