Are black holes in alternative theories serious astrophysical candidates? The case for Einstein-dilaton-Gauss-Bonnet black holes

Journal Article · Wed Apr 15 04:00:00 EDT 2009 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PHYSREVD.79.084031· OSTI ID:21308326

Pani, Paolo; Cardoso, Vitor ^[1]

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1. Dipartimento di Fisica, Universita di Cagliari, and INFN sezione di Cagliari, Cittadella Universitaria 09042 Monserrato (Italy)

It is generally accepted that Einstein's theory will get some as yet unknown corrections, possibly large in the strong-field regime. An ideal place to look for these modifications is in the vicinities of compact objects such as black holes. Here, we study dilatonic black holes, which arise in the framework of Gauss-Bonnet couplings and one-loop corrected four-dimensional effective theory of heterotic superstrings at low energies. These are interesting objects as a prototype for alternative, yet well-behaved gravity theories: they evade the 'no-hair' theorem of general relativity but were proven to be stable against radial perturbations. We investigate the viability of these black holes as astrophysical objects and try to provide some means to distinguish them from black holes in general relativity. We start by extending previous works and establishing the stability of these black holes against axial perturbations. We then look for solutions of the field equations describing slowly rotating black holes and study geodesic motion around this geometry. Depending on the values of mass, dilaton charge, and angular momentum of the solution, one can have differences in the innermost-stable-circular-orbit location and orbital frequency, relative to black holes in general relativity. In the most favorable cases, the difference amounts to a few percent. Given the current state-of-the-art, we discuss the difficulty of distinguishing the correct theory of gravity from electromagnetic observations or even with gravitational-wave detectors.

• OSTI ID: 21308326
• Journal Information: Physical Review. D, Particles Fields, Journal Name: Physical Review. D, Particles Fields Journal Issue: 8 Vol. 79; ISSN PRVDAQ; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ANGULAR MOMENTUM
ASTROPHYSICS
BLACK HOLES
COUPLING
DISTURBANCES
EINSTEIN FIELD EQUATIONS
FOUR-DIMENSIONAL CALCULATIONS
GENERAL RELATIVITY THEORY
GRAVITATION
GRAVITATIONAL WAVE DETECTORS
MASS
MATHEMATICAL SOLUTIONS
MODIFICATIONS
ORBITS
PERTURBATION THEORY
STABILITY
SUPERSTRING MODELS