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Static and stationary regular black holes are examined under a minimal set of requirements consisting of (i) the existence of a well defined event horizon and (ii) the weak energy condition for matter sourcing the geometry. We perform our…

General Relativity and Quantum Cosmology · Physics 2023-07-24 Jorge Ovalle , Roberto Casadio , Andrea Giusti

We show that the integral method used to prove the no-hair theorem for Black Holes (BH's) in spherically symmetric and static spacetimes within the framework of general relativity with matter composed by a complex-valued scalar-field does…

General Relativity and Quantum Cosmology · Physics 2019-02-27 Gustavo Garcia , Marcelo Salgado

The prediction of spacetime singularities, regions of infinite curvature where classical physics breaks down, is one of the most profound challenges in General Relativity (GR). In particular, black hole solutions such as the Schwarzschild…

General Relativity and Quantum Cosmology · Physics 2025-11-18 Jose Pinedo Soto

We present a family of solutions of Einstein's gravity minimally coupled to a complex, massive scalar field, describing asymptotically flat, spinning black holes with scalar hair and a regular horizon. These hairy black holes (HBHs) are…

General Relativity and Quantum Cosmology · Physics 2014-06-11 Carlos A. R. Herdeiro , Eugen Radu

We investigate the polarized images of an equatorial emitting ring around a Konoplya-Zhidenko rotating non-Kerr black hole, which introduces an additional deformation parameter. The deformation parameter $\eta$ allows the spin parameter to…

General Relativity and Quantum Cosmology · Physics 2025-12-30 Xin Qin , Fen Long , Songbai Chen , Jiliang Jing

Rotating black hole solutions in theories of modified gravity are important as they offer an arena to test these theories through astrophysical observation. The non-rotating black hole can be hardly tested since the black hole spin is very…

General Relativity and Quantum Cosmology · Physics 2018-09-28 Rahul Kumar , Sushant G. Ghosh

We compare the fully nonlinear and perturbative evolution of nonrotating black holes with odd-parity distortions utilizing the perturbative results to interpret the nonlinear results. This introduction of the second polarization…

General Relativity and Quantum Cosmology · Physics 2009-10-31 J Baker , S Brandt , M Campanelli , C O Lousto , E Seidel , R Takahashi

We investigate the finite-time instability of massive spinning test particles around a rotating hairy black hole generated through gravitational decoupling. The particle motion is described by the full Mathisson-Papapetrou-Dixon equations…

General Relativity and Quantum Cosmology · Physics 2026-05-20 Surojit Dalui , Xian-Hui Ge

The spins of a number of supermassive and stellar-mass black holes have been measured based on detections of thermal continuum emission and relativistically broadened iron lines in their x-ray spectra. Likewise, quasiperiodic variability…

High Energy Astrophysical Phenomena · Physics 2015-06-23 Tim Johannsen

According to the no-hair theorem, astrophysical black holes are uniquely characterized by their masses and spins and are described by the Kerr metric. Several parametric spacetimes which deviate from the Kerr metric have been proposed in…

General Relativity and Quantum Cosmology · Physics 2015-12-16 Tim Johannsen

In this second paper, we develop an analytical theory of quasi-equatorial lensing by Kerr black holes. In this setting we solve perturbatively our general lens equation with displacement given in Paper I, going beyond weak-deflection Kerr…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-27 Amir B. Aazami , Charles R. Keeton , A. O. Petters

As with any black hole, asymptotically anti-de Sitter Kerr black holes are described by a small number of parameters, including a "mass parameter" $M$ that reduces to the AdS-Schwarzschild mass in the limit of vanishing angular momentum. In…

General Relativity and Quantum Cosmology · Physics 2015-11-10 Brett McInnes , Yen Chin Ong

Perturbed Kerr black holes emit gravitational radiation, which (for the practical purposes of gravitational-wave astronomy) consists of a superposition of damped sinusoids termed quasi-normal modes. The frequencies and time-constants of the…

General Relativity and Quantum Cosmology · Physics 2013-05-30 Ioannis Kamaretsos , Mark Hannam , Sascha Husa , B. S. Sathyaprakash

The Detweiler-Barack-Sago redshift function for particles moving along slightly eccentric equatorial orbits around a Kerr black hole is currently known up to the second order in eccentricity, second order in spin parameter, and the 8.5…

General Relativity and Quantum Cosmology · Physics 2019-11-13 Donato Bini , Andrea Geralico

The Kerr metric is one of the most important solutions to Einstein's field equations, describing the gravitational field outside a rotating black hole. We thoroughly analyze the curvature scalar invariants to study the Kerr spacetime by…

General Relativity and Quantum Cosmology · Physics 2013-10-10 Majd Abdelqader , Kayll Lake

We investigate timelike geodesics in asymptotically flat regular black holes supported by a phantom scalar field characterized by a scalar charge $A$. This parameter removes the central singularity and continuously deforms the Schwarzschild…

General Relativity and Quantum Cosmology · Physics 2026-04-23 P. A. González , Marco Olivares , Eleftherios Papantonopoulos , Yerko Vásquez

The no-hair theorem characterizes the fundamental nature of black holes in general relativity. This theorem can be tested observationally by measuring the mass and spin of a black hole as well as its quadrupole moment, which may deviate…

High Energy Astrophysical Phenomena · Physics 2016-08-24 Tim Johannsen

The open question of whether a black hole can become tidally deformed by an external gravitational field has profound implications for fundamental physics, astrophysics and gravitational-wave astronomy. Love tensors characterize the tidal…

General Relativity and Quantum Cosmology · Physics 2021-04-02 Alexandre Le Tiec , Marc Casals

We discuss parameterizations of black-hole spacetimes in and beyond General Relativity in view of their symmetry constraints: within the class of axisymmetric, stationary spacetimes, we propose a parameterization that includes non-circular…

General Relativity and Quantum Cosmology · Physics 2022-06-14 Héloïse Delaporte , Astrid Eichhorn , Aaron Held

The Event Horizon Telescope (EHT) image of M87* provides a direct test of strong-field gravity, measuring an angular shadow diameter $\theta_{d}=42\pm 3~\mu\mathrm{as}$ and a circularity deviation $\Delta C\leq 0.1$. Such observations allow…

General Relativity and Quantum Cosmology · Physics 2026-05-13 Kourosh Nozari , Milad Hajebrahimi , Sara Saghafi , G. Mustafa , Emmanuel N. Saridakis