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Title: Gravitational instabilities of superspinars

Abstract

Superspinars are ultracompact objects whose mass M and angular momentum J violate the Kerr bound (cJ/GM{sup 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.

Authors:
; ; ;  [1];  [2];  [3];  [4]
  1. Dipartimento di Fisica, Universita di Cagliari, and INFN sezione di Cagliari, Cittadella Universitaria 09042 Monserrato (Italy)
  2. (United States)
  3. (United States) and Theoretical Astrophysics 350-17, California Institute of Technology, Pasadena, California 91125 (United States)
  4. (Portugal) and Department of Physics and Astronomy, The University of Mississippi, University, Mississippi 38677-1848 (United States)
Publication Date:
OSTI Identifier:
21420946
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. D, Particles Fields; Journal Volume: 82; Journal Issue: 4; Other Information: DOI: 10.1103/PhysRevD.82.044009; (c) 2010 American Institute of Physics
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTROPHYSICS; BLACK HOLES; BOUNDARY CONDITIONS; DISTURBANCES; GRAVITATIONAL INSTABILITY; GRAVITATIONAL LENSES; KERR FIELD; MASS; PERTURBATION THEORY; SPIN; STABILITY; ANGULAR MOMENTUM; GRAVITATIONAL FIELDS; INSTABILITY; LENSES; PARTICLE PROPERTIES; PHYSICS; PLASMA INSTABILITY

Citation Formats

Pani, Paolo, Barausse, Enrico, Berti, Emanuele, Cardoso, Vitor, Maryland Center for Fundamental Physics, Department of Physics, University of Maryland, College Park, Maryland 20742, Department of Physics and Astronomy, University of Mississippi, University, Mississippi 38677-1848, and Centro Multidisciplinar de Astrofisica - CENTRA, Department de Fisica, Instituto Superior Tecnico, Avenida Rovisco Pais 1, 1049-001 Lisboa. Gravitational instabilities of superspinars. United States: N. p., 2010. Web. doi:10.1103/PHYSREVD.82.044009.
Pani, Paolo, Barausse, Enrico, Berti, Emanuele, Cardoso, Vitor, Maryland Center for Fundamental Physics, Department of Physics, University of Maryland, College Park, Maryland 20742, Department of Physics and Astronomy, University of Mississippi, University, Mississippi 38677-1848, & Centro Multidisciplinar de Astrofisica - CENTRA, Department de Fisica, Instituto Superior Tecnico, Avenida Rovisco Pais 1, 1049-001 Lisboa. Gravitational instabilities of superspinars. United States. doi:10.1103/PHYSREVD.82.044009.
Pani, Paolo, Barausse, Enrico, Berti, Emanuele, Cardoso, Vitor, Maryland Center for Fundamental Physics, Department of Physics, University of Maryland, College Park, Maryland 20742, Department of Physics and Astronomy, University of Mississippi, University, Mississippi 38677-1848, and Centro Multidisciplinar de Astrofisica - CENTRA, Department de Fisica, Instituto Superior Tecnico, Avenida Rovisco Pais 1, 1049-001 Lisboa. Sun . "Gravitational instabilities of superspinars". United States. doi:10.1103/PHYSREVD.82.044009.
@article{osti_21420946,
title = {Gravitational instabilities of superspinars},
author = {Pani, Paolo and Barausse, Enrico and Berti, Emanuele and Cardoso, Vitor and Maryland Center for Fundamental Physics, Department of Physics, University of Maryland, College Park, Maryland 20742 and Department of Physics and Astronomy, University of Mississippi, University, Mississippi 38677-1848 and Centro Multidisciplinar de Astrofisica - CENTRA, Department de Fisica, Instituto Superior Tecnico, Avenida Rovisco Pais 1, 1049-001 Lisboa},
abstractNote = {Superspinars are ultracompact objects whose mass M and angular momentum J violate the Kerr bound (cJ/GM{sup 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.},
doi = {10.1103/PHYSREVD.82.044009},
journal = {Physical Review. D, Particles Fields},
number = 4,
volume = 82,
place = {United States},
year = {Sun Aug 15 00:00:00 EDT 2010},
month = {Sun Aug 15 00:00:00 EDT 2010}
}