Publication date: Oct 2014
Abstract:
We demonstrate possible optical signatures of the Kehagias-Sfetsos (KS)
naked singularity spacetimes representing a spherically symmetric vacuum
solution of the modified Hořava gravity. In such spacetimes, accretion
structures significantly different from those present in standard black
hole spacetimes occur due to the ‘antigravity’ effect, which causes an
internal static sphere surrounded by Keplerian discs. We focus our
attention on the optical effects related to the Keplerian accretion
discs, constructing the optical appearance of the Keplerian discs, the
spectral continuum due to their thermal radiation, and the spectral
profiled lines generated in the innermost parts of such discs. The KS
naked singularity signature is strongly encoded in the characteristics
of predicted optical effects, especially in cases where the spectral
continuum and spectral lines are profiled by the strong gravity of the
spacetimes due to the vanishing region of the angular velocity gradient
influencing the effectiveness of the viscosity mechanism. We can
conclude that optical signatures of KS naked singularities can be well
distinguished from the signatures of standard black holes.
Authors:
Stuchlík, Zdeněk; Schee, Jan;