Disforming the Kerr metric. (arXiv:2006.06461v1 [gr-qc])
<a href="http://arxiv.org/find/gr-qc/1/au:+Anson_T/0/1/0/all/0/1">Timothy Anson</a>, <a href="http://arxiv.org/find/gr-qc/1/au:+Babichev_E/0/1/0/all/0/1">Eugeny Babichev</a>, <a href="http://arxiv.org/find/gr-qc/1/au:+Charmousis_C/0/1/0/all/0/1">Christos Charmousis</a>, <a href="http://arxiv.org/find/gr-qc/1/au:+Hassaine_M/0/1/0/all/0/1">Mokhtar Hassaine</a>
Starting from a recently constructed stealth Kerr solution of higher order
scalar tensor theory involving scalar hair, we analytically construct disformal
versions of the Kerr spacetime with a constant degree of disformality and a
regular scalar field. While the disformed metric has only a ring singularity
and asymptotically is quite similar to Kerr, it is found to be neither Ricci
flat nor circular. Non-circularity has far reaching consequences on the
structure of the solution. As we approach the rotating compact object from
asymptotic infinity we find a static limit ergosurface similar to the Kerr
spacetime with an enclosed ergoregion. However, the stationary limit of
infalling observers is found to be a timelike hypersurface. A candidate event
horizon is found in the interior of this stationary limit surface. It is a null
hypersurface generated by a null congruence of light rays which are no longer
Killing vectors.
Starting from a recently constructed stealth Kerr solution of higher order
scalar tensor theory involving scalar hair, we analytically construct disformal
versions of the Kerr spacetime with a constant degree of disformality and a
regular scalar field. While the disformed metric has only a ring singularity
and asymptotically is quite similar to Kerr, it is found to be neither Ricci
flat nor circular. Non-circularity has far reaching consequences on the
structure of the solution. As we approach the rotating compact object from
asymptotic infinity we find a static limit ergosurface similar to the Kerr
spacetime with an enclosed ergoregion. However, the stationary limit of
infalling observers is found to be a timelike hypersurface. A candidate event
horizon is found in the interior of this stationary limit surface. It is a null
hypersurface generated by a null congruence of light rays which are no longer
Killing vectors.
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