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The final ringdown phase in a coalescence process is a valuable laboratory to test General Relativity and potentially constrain additional degrees of freedom in the gravitational sector. We introduce here an effective description for…

High Energy Physics - Theory · Physics 2019-03-27 Gabriele Franciolini , Lam Hui , Riccardo Penco , Luca Santoni , Enrico Trincherini

A large class of spherically symmetric static extremal black hole spacetimes possesses a stable null photon sphere on their horizons. For the extremal Kerr-Newman family, the photon sphere only really coincides with the horizon in the sense…

General Relativity and Quantum Cosmology · Physics 2017-11-06 Zi-Yu Tang , Yen Chin Ong , Bin Wang

The aim of the present article is to evaluate the motion of charged test particles in the vicinity of a near-extremal rotating black hole in the presence of magnetic fields. Euler-Lagrange motion equations and effective potential methods…

General Relativity and Quantum Cosmology · Physics 2021-02-03 C. H. Coimbra-Araújo , R. C. Anjos

Near-extremal black holes are subject to large quantum effects, which modify their low-temperature thermodynamic behavior. Hitherto, these quantum effects were analyzed by separating the geometry into the near-horizon region and its…

High Energy Physics - Theory · Physics 2025-10-06 Maciej Kolanowski , Donald Marolf , Ilija Rakic , Mukund Rangamani , Gustavo J. Turiaci

The motion of a point charged particle moving in the background of the critical power Maxwell charged AdS black holes, in a probe approximation is studied. The extended phase space, where the cosmological constant appears as a pressure, is…

General Relativity and Quantum Cosmology · Physics 2018-05-09 S. H. Hendi , Z. S. Taghadomi , C. Corda

In this work, we explore the critical parameters that delineate the existence of black holes, identifying the permissible ranges that facilitate their formation. A comprehensive thermodynamic analysis of black holes is conducted, leading to…

General Relativity and Quantum Cosmology · Physics 2025-11-04 Farokhnaz Hosseinifar , Shahin Mamedov , Filip Studnička , Hassan Hassanabadi

We investigate dynamics of probe particles moving in the near-horizon limit of (2N+1)-dimensional extremal Myers-Perry black hole with arbitrary rotation parameters. We observe that in the most general case with nonequal nonvanishing…

High Energy Physics - Theory · Physics 2017-10-10 Tigran Hakobyan , Armen Nersessian , M. M. Sheikh-Jabbari

We study charged particle motion in weakly charged higher dimensional black holes. To describe the electromagnetic field we use a test field approximation and use the higher dimensional Kerr-NUT-(A)dS metric as a background geometry. It is…

High Energy Physics - Theory · Physics 2011-02-03 Valeri P. Frolov , Pavel Krtous

The quasi-bound states of charged massive scalar fields in the near-extremal charged Reissner-Nordstr\"om black-hole spacetime are studied {\it analytically}. These discrete resonant modes of the composed black-hole-field system are…

High Energy Physics - Theory · Physics 2017-06-08 Shahar Hod

In viable models of minicharged dark matter, astrophysical black holes might be charged under a hidden $U(1)$ symmetry and are formally described by the same Kerr-Newman solution of Einstein-Maxwell theory. These objects are unique probes…

High Energy Physics - Phenomenology · Physics 2020-03-26 Vitor Cardoso , Caio F. B. Macedo , Paolo Pani , Valeria Ferrari

We study massive scalar quasinormal spectra of charged Einstein--Maxwell--dilaton black holes by combining high-order WKB--Pad\'e calculations with time-domain evolution. The two approaches show close agreement in the regime where both…

General Relativity and Quantum Cosmology · Physics 2026-04-15 S. V. Bolokhov

It is known that magnetic fields exist near black holes and photons can go around black holes due to strong gravity. Utilizing these facts, we can probe hypothetical pseudoscalar particles, so-called axions. In fact, photons can be…

High Energy Physics - Phenomenology · Physics 2023-06-12 Kimihiro Nomura , Kaishu Saito , Jiro Soda

Fluctuations around critical behavior of a holographic charged plasmas are investigated by studying quasi-normal modes of the corresponding black branes in 5D Einstein-Maxwell-Dilaton gravity. The near horizon geometry of black branes…

High Energy Physics - Theory · Physics 2022-06-22 Umut Gursoy , Matti Järvinen , Giuseppe Policastro , Natale Zinnato

Near-extremal primordial black holes stable over cosmological timescales may constitute a significant fraction of the dark matter. Due to their charge the coalescence rate of such black holes is enhanced inside clusters and the non-extremal…

General Relativity and Quantum Cosmology · Physics 2022-06-24 Konstantinos Kritos , Joseph Silk

We consider the minimally coupled Klein-Gordon equation for a charged, massive scalar field in the non-extremal Reissner-Nordstr\"om background. Performing a frequency domain analysis, using a continued fraction method, we compute the…

General Relativity and Quantum Cosmology · Physics 2015-06-15 Juan Carlos Degollado , Carlos A. R. Herdeiro

Superradiance provides a unique opportunity for investigating dark sectors as well as primordial black holes, which themselves are candidates for dark matter over a wide mass range. Using axion-like particles as an example, we show that…

High Energy Physics - Phenomenology · Physics 2025-01-22 James B. Dent , Bhaskar Dutta , Tao Xu

In this paper, we consider charged accelerating AdS black holes with nonlinear electromagnetic source. The metric chosen by us is of a regular black hole which shows regular nature at poles and a conical effect which corresponds to a cosmic…

General Relativity and Quantum Cosmology · Physics 2019-03-18 Amritendu Haldar , Ritabrata Biswas

We investigate the epicyclic motion of charged test particles and the associated quasi-periodic oscillations (QPOs) around a weakly magnetized black hole surrounded by quintessence within the framework of Einstein-ModMax theory. We analyze…

General Relativity and Quantum Cosmology · Physics 2026-01-07 Hamza Rehman , Sanjar Shaymatov , Tao Zhu

Using sophisticated string theory calculations, Maldacena and Susskind have intriguingly shown that near-extremal black holes are characterized by a {\it finite} mass gap above the corresponding zero-temperature (extremal) black-hole…

General Relativity and Quantum Cosmology · Physics 2021-07-07 Shahar Hod

We investigate the quasinormal modes of the Reissner$-$Nordstr\"om anti$-$de Sitter black hole using the Penrose limit, motivated by the geometrical optics approximation. This approach offers a novel framework for approximating quasinormal…

General Relativity and Quantum Cosmology · Physics 2025-03-21 Shubham Kala , Anik Rudra , Hemwati Nandan