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

By Paolo Pani, V. Cardoso. 2009

172 citations recorded by the source corpus.

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 tomore » 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.« less

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/9dd071c2b42fc6d4f23fc191e041124a0058524e

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Citations in the corpus

Stellar structure models in modified theories of gravity: Lessons and challenges (2019, background): “For the FPS EOS with β = √ 2 [282] one finds α < 23M2 ⊙, which improves previous bounds on EDGB gravity from black holes [283].”
Kerr black holes with Proca hair (2016, background): “g [35–42]); or 6) several of the above.”
Approximate Universal Relations for Neutron Stars and Quark Stars (2016, background): “Current stringent constraints on EDGB gravity come from observations of the rate of change of the orbital period in a low-mass X-ray binary (LMXB) system [300] and the existence of stellar-mass black holes [301].”
Doing Science with eLISA: Astrophysics and Cosmology in the Millihertz Regime (2012, background): “The fact that black hole oscillations should produce different radiation spectra in different theories of gravity is true in general (Barausse and Sotiriou, 2008), and the spectrum was studied in some specific extensions of GR, such as Einstein-dilatonGauss-Bonnet gravity (Pani and Cardoso, 2009).”