For a stationary, axisymmetric, asymptotically flat, ultra-compact [$i.e.$ containing light-rings (LRs)] object, with $\mathbb{Z}_2$ north-south symmetry fixing an equatorial plane, we establish that the structure of timelike circular orbits (TCOs) in vicinity LRs, for either rotation direction, depends exclusively on radial stability LRs. Thus, unstable LR delimits region TCOs (no TCOs) radial...

We find that the Kerr-(Newman)-AdS$_4$ black hole will be shadowless if its rotation parameter is larger than a critical value and shadowless-ness may related to appearance of null hypersurface caustics (NHC) both inside Cauchy horizon outside event for with beyond value. Our studies also further confirm whether an ultraspinning super-entropic or not unrelated existence NHC horizon.

Near horizon Bondi-Metzner-Sachs (BMS) like symmetry is spontaneously broken by the black hole background itself and hence gives rise to Goldstone mode. The associated mode for near BMS of a Schwarzschild was found behave inverted harmonic oscillators, which has been further shown lead thermodynamic temperature in semi-classical regime. Here we investigate generalization this previous findings ...

We present an improved metric form of the complete family exact black hole spacetimes algebraic type D, including any cosmological constant. This class was found by Debever in 1971, Pleba\ifmmode \acute{n}\else \'{n}\fi{}ski and Demia\ifmmode 1976, conveniently reformulated Griffiths Podolsk\'y 2005. In our new this key functions are simplified, partially factorized, fully explicit. They depend...

We write the Kerr–Schild tetrads in terms of flat space–time and a (1, 1) tensor Sμλ. This can be considered as projection operator, since it transforms (i) into non-flat tetrads, vice-versa, (ii) Minkowski metric tensor, vice-versa. The Sμλ its inverse are constructed standard null vector field lμ that defines form general relativity, yields black holes non-linear gravitational waves solutions...

Abstract Recently, Kumar and Ghosh have derived Kerr-like rotating black hole solutions in the framework of four-dimensional Einstein–Gauss–Bonnet theory gravity investigated shadow. Using steady-state Novikov–Thorne model, we study thin accretion disk processes for such holes including energy flux, temperature distribution, emission spectrum, conversion efficiency as well radius innermost stab...

We have studied the spacetime of a Kerr black hole immersed in Melvin magnetic field, and found Melvin-Kerr shadow becomes more elongated as field parameter $B$ increases. not only that an unstable light ring could exist but also stable exist. The radius increases with increase $B$, it is opposite for ring. For certain rotation $a$, both prograde retrograde (stable) rings when less than critica...

We describe a simple magneto-optical experiment and introduce a magneto-optical Kramers-Kronig analysis (MOKKA) that together allow extracting the complex dielectric function for left- and right-handed circular polarizations in a broad range of frequencies without actually generating circularly polarized light. The experiment consists of measuring reflectivity and Kerr rotation, or alternativel...