Distinguishing black holes from naked singularities through their accretion disc properties

By P. Joshi, D. Malafarina, Ramesh Narayan. 2013

164 citations recorded by the source corpus.

We show that, in principle, a slowly evolving gravitationally collapsing perfect fluid cloud can asymptotically settle to a static spherically symmetric equilibrium configuration with a naked singularity at the center. We consider one such asymptotic final configuration with a finite outer radius, and construct a toy model in which it is matched to a Schwarzschild exterior geometry. We examine the properties of circular orbits in this model. We then investigate the observational signatures of a thermal accretion disc in this spacetime, comparing them with the signatures expected for a disc around a black hole of the same mass. Several notable differences emerge. A disc around the naked singularity is much more luminous than one around an equivalent black hole. Also, the disc around the naked singularity has a spectrum with a high frequency power law segment that carries a major fraction of the total luminosity. Thus, at least some naked singularities can, in principle, be distinguished observationally from the black holes of the same mass. We discuss the possible implications of these results.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/37f8017e7c9e89af6ba5411ab9774bcd35d64be1

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In Astronomy and Astrophysics

Citations in the corpus

Constraining the spin and the deformation parameters from the black hole shadow (2014, background): “The result is that right now we can only rule out the possibility that BH candidates are some kinds of very exotic objects, like some types of wormholes [26] or some exotic compact objects without event horizon [27, 28].”