46 papers
Renormalization-group improved Schwarzschild black hole: shadow, ringdown, and strong cosmic censorship
Ahmad Al-Badawi, Faizuddin Ahmed, İzzet Sakallı
A renormalization-group (RG) improved Schwarzschild-like black hole (BH) is studied here, with a lapse that interpolates between a classical Schwarzschild exterior and a quantum-sm…
MCMC Constraints on Dyonic Kalb-Ramond Black Holes with a Cloud of Strings from Twin-Peak QPOs and EHT Shadows
Faizuddin Ahmed, Ahmad Al-Badawi, İzzet Sakallı
We study a dyonic black hole in a Lorentz-violating gravity that carries a background Kalb--Ramond field and is pierced by a cloud of strings. The resulting metric reduces to the r…
Are Petrov type-N and D spacetimes admitting CTCs valid in gravity?
Faizuddin Ahmed, Ahmad Al-Badawi, İzzet Sakallı
We ask whether two classical time-machine geometries, the Ori (2005) compact-vacuum-core metric and the Ahmed (2018) four-dimensional generalisation of Misner space, remain admissi…
Astrophysical signatures of Kerr-Bertotti-Robinson black holes in a cloud of strings: ISCO, microquasar QPOs, and Bondi-Hoyle-Lyttleton accretion
Faizuddin Ahmed, Orhan Donmez, Ahmad Al-Badawi +1
We study test-particle dynamics in the equatorial plane of a Kerr-Bertotti-Robinson black hole (BH) immersed in a cloud of strings (CS), with mass M , rotation a, magnetic paramete…
Astrophysical Signatures of Einstein-Skyrme Anti-de Sitter Black Holes: Epicyclic Frequencies and QPO Constraints
Faizuddin Ahmed, Ahmad Al-Badawi, İzzet Sakallı
We study the geodesic motion and epicyclic oscillations of massive test particles around a static, spherically symmetric black hole (BH) solution of the Einstein--Skyrme (ES) theor…
Spin-(, , ) Field Perturbations, Quasinormal Modes, Overtones, Greybody Factors and Strong Cosmic Censorship of Einstein-Skyrme Black Holes
Faizuddin Ahmed, Ahmad Al-Badawi, İzzet Sakallı
We carry out a multi-spin perturbation-theory study of the four-dimensional Einstein-Skyrme (ES) anti-de Sitter (AdS) black hole (BH), whose lapse i…