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We study odd parity perturbations of spherically symmetric black holes with time-dependent scalar hair in shift-symmetric higher-order scalar-tensor theories. The analysis is performed in a general way without assuming the degeneracy…

General Relativity and Quantum Cosmology · Physics 2021-04-28 Keitaro Tomikawa , Tsutomu Kobayashi

In this work we have deformed regular black holes which possess a general mass term described by a function which generalizes the Bardeen and Hayward mass functions. By using linear constraints in the energy-momentum tensor to generate…

General Relativity and Quantum Cosmology · Physics 2017-06-29 J. C. S. Neves

A Kerr black hole with mass parameter m and angular momentum parameter a acting as a gravitational lens gives rise to two images in the weak field limit. We study the corresponding magnification relations, namely the signed and absolute…

General Relativity and Quantum Cosmology · Physics 2008-11-26 M. C. Werner , A. O. Petters

We reveal the effect of the spacetime parameters on the accretion morphology formed through the BHL mechanism around a slowly rotating disformal Kerr black hole. Thus, we investigate the measurable signatures of these parameters on the…

High Energy Astrophysical Phenomena · Physics 2026-05-18 Orhan Donmez , M. Yousaf , Imtiaz Khan , G. Mustafa

Generalizations of the Schwarzschild and Kerr black holes are discussed in an astrophysically viable generalized theory of gravity, which includes higher curvature corrections in the form of the Gauss-Bonnet term, coupled to a dilaton. The…

We investigate a complete family of spacetimes which represent black holes with rotation, NUT twist, acceleration, electric and magnetic charges. These are exact solutions of the Einstein-Maxwell equations with any cosmological constant,…

General Relativity and Quantum Cosmology · Physics 2025-07-08 Hryhorii Ovcharenko , Jiri Podolsky , Marco Astorino

In recent years, the shape of the photon ring in black holes images has been argued to provide a sharp test of the Kerr hypothesis for future black hole imaging missions. In this work, we confront this proposal to beyond Kerr geometries and…

General Relativity and Quantum Cosmology · Physics 2026-03-27 Jibril Ben Achour , Eric Gourgoulhon , Hugo Roussille

Recent advancements in observational techniques have led to new tests of the general relativistic predictions for black-hole spacetimes in the strong-field regime. One of the key ingredients for several tests is a metric that allows for…

General Relativity and Quantum Cosmology · Physics 2023-02-22 Dirk Heumann , Dimitrios Psaltis

In this paper, we use a suitable conformal rescaling to construct static and rotating regular black holes in conformal massive gravity. The new metric is characterized by the mass $M$, the "scalar charge" $Q$, the angular momentum parameter…

General Relativity and Quantum Cosmology · Physics 2020-02-18 Kimet Jusufi , Mubasher Jamil , Hrishikesh Chakrabarty , Qiang Wu , Cosimo Bambi , Anzhong Wang

As an extension of our previous work [1] (arXiv:2409.02308), we study a complete family of type D black holes with Kerr-like rotation, NUT twist, acceleration, electric and magnetic charges, and any value of the cosmological constant…

General Relativity and Quantum Cosmology · Physics 2025-07-08 Hryhorii Ovcharenko , Jiri Podolsky , Marco Astorino

We consider a black hole mimicker given by an exact solution of the stationary and axially symmetric field equations in vacuum known as the $\delta$-Kerr metric. We study its optical properties based on a ray-tracing code for photon motion…

General Relativity and Quantum Cosmology · Physics 2022-07-25 Song Li , Temurbek Mirzaev , Ahmadjon A. Abdujabbarov , Daniele Malafarina , Bobomurat Ahmedov , Wen-Biao Han

We continue the study of spherically symmetric black hole solutions in torsion bigravity, a class of Einstein-Cartan-type gravity theories involving, besides a metric, a massive propagating torsion field. In the infinite-range limit, these…

General Relativity and Quantum Cosmology · Physics 2020-12-09 Vasilisa Nikiforova

Ongoing observations in the strong-field regime are in optimal agreement with general relativity, although current errors still leave room for small deviations from Einstein's theory. Here we summarise our recent results on superradiance of…

General Relativity and Quantum Cosmology · Physics 2021-05-20 Mauro Oi , Edgardo Franzin , Stefano Liberati

We introduce a systematic and direct procedure to generate hairy rotating black holes by deforming a spherically symmetric seed solution. We develop our analysis in the context of the gravitational decoupling approach, without resorting to…

General Relativity and Quantum Cosmology · Physics 2021-02-12 E. Contreras , J. Ovalle , R. Casadio

A gravitational theory is formulated by considering the physical processes underlying relativistic dilation of time and contraction of space. It is shown that the point mass solution of general relativity's field equation - the…

General Relativity and Quantum Cosmology · Physics 2015-08-25 James W. Douglass

According to the no-hair theorem, astrophysical black holes are fully characterized by their masses and spins and are described by the Kerr metric. This theorem can be tested observationally by measuring (at least) three different multipole…

High Energy Astrophysical Phenomena · Physics 2015-06-04 Tim Johannsen , Dimitrios Psaltis

We study the shadow of the Cardoso-Pani-Rico (CPR) black hole for different values of the black hole spin $a_*$, the deformation parameters $\epsilon_3^t$ and $\epsilon_3^r$, and the viewing angle $i$. We find that the main impact of the…

General Relativity and Quantum Cosmology · Physics 2015-07-08 M. Ghasemi-Nodehi , Zilong Li , Cosimo Bambi

We report on the first numerical-relativity simulations of black-hole binaries that deviate from General Relativity due to quadratic-curvature corrections. Said theory of Quadratic Gravity propagates additional massive modes and admits both…

General Relativity and Quantum Cosmology · Physics 2025-03-18 Aaron Held , Hyun Lim

Breitenlohner, Maison and Gibbons claimed some time ago that all bona-fide four dimensional asymptotically flat non-degenerate black holes are in a symmetry orbit of the Schwarzschild/Kerr black hole in a large set of theories of gravity…

High Energy Physics - Theory · Physics 2015-05-28 Josef Lindman Hörnlund

The spacetime singularities in classical general relativity are inevitable, which are also predicated by the celebrated singularity theorems. However, it is general belief that singularities do not exist in the nature and they are the…

General Relativity and Quantum Cosmology · Physics 2015-10-20 Sushant G. Ghosh