Circular Geodesics in the Kerr-Newman-Taub-NUT Space-time

Understand

In this paper we investigate the equatorial causal (time-like and null) circular geodesics of the Kerr-Newman-Taub-NUT(Newman-Unti-Tamburino) black hole in four dimensional Lorentzian geometry.

• The special characteristics of this black hole is that it is of \emph{Petrov-Pirani type D} and the photon trajectories are \emph{doubly degenerate principal null congruence}.
• We derive the conditions for existence of innermost stable circular orbit, marginally bound circular orbit and circular photon orbit in the background of Kerr-Newman-Taub-NUT(KNTN) space-time.
• The effective potential for both time-like case and null cases have been studied.