Abstract
We study the strong gravitational lensing in the background of a rotating non-Kerr compact object with a deformed parameter and an unbound rotation parameter . We find that the marginally circular stable orbit radius and the deflection angle depend sharply on the parameters and . For the case in which the black hole is more prolate than a Kerr black hole, the marginally circular photon orbit exists only in the regime for a prograde photon. The upper limit is a function of the rotation parameter . As , the deflection angle of the light ray very close to the naked singularity is a positive finite value, which is different from that in the rotating naked singularity described by Janis-Newman-Winicour metric. For the oblate black hole and the retrograde photon, there does not exist such a threshold value. Modeling the supermassive central object of the Galaxy as a rotating non-Kerr compact object, we estimated the numerical values of the coefficients and observables for gravitational lensing in the strong field limit.
3 More- Received 16 April 2012
DOI:https://doi.org/10.1103/PhysRevD.85.124029
© 2012 American Physical Society