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;