Distinguishing Kerr naked singularities and black holes using the spin precession of a test gyro in strong gravitational fields

Circular orbits in Kerr-Taub-NUT spacetime and their implications for accreting black holes and naked singularities

“…One should note that r = 0 is relevant only for the KTN NS case, because r = 0 is hidden inside the horizon in the BH case. However, if n vanishes, V eff will diverge at r = 0, which could be realized from the Kerr geometry, as r = 0, θ = π/2 represents the ring singularity [27,30]. Such a singularity does not exist at that particular point (r = 0, θ = π/2) in the KTN geometry.…”

“…. meet at the singularity (r = 0) with Ω ± | r=0 = 1/a [30], but for KTN NS Ω ± take two different values at r = 0 :…”

“…Though this is completely a new thing but not unusual in the strong gravity regime. Note that the orbital plane precession or the Lense-Thirring precession can also vanish (seefigure 2of[24]) in the strong gravity regime in case of a KTN BH[39,40,41], which does not occur for a Kerr BH[30].…”

Fingerprints of the Cosmological Constant: Folds in the Profiles of the Axionic Dark Matter Distribution in a Dyon Exterior

“…The profiles of the axion field distribution inherit the fold-like structure of the profiles of the metric function N (x). (34). The basic profile has the typical fold-like structure: the minimum, the barrier on the left of the minimum, the maximum on its right-hand side.…”

Observers in Kerr spacetimes: the ergoregion on the equatorial plane

“…In this work, we clarify and deepen those results, formulate in detail those considerations, analyze the static limit, and perform a detailed study of this region from the point of view of stationary observers. In this regards, we mention also the interesting and recent results published in [106] and [107].…”