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Dynamical Chern-Simons gravity, a parity-violating modification of general relativity, is regarded as a low-energy effective theory arising from string theory. Gravitational waves provide a powerful probe for testing its predictions.…

General Relativity and Quantum Cosmology · Physics 2025-12-30 Xinyi Che , Xiangyu Lyu , Changfu Shi

In the framework of the Asymptotic Safety scenario for quantum gravity, we analyze quantum gravity modifications to the thermal characteristics of a thin accretion disk spiraling around a renormalization group improved (RGI-) Kerr black…

General Relativity and Quantum Cosmology · Physics 2024-07-01 Luis A. Sánchez

Stellar-mass black holes offer what is perhaps the best scenario to test theories of gravity in the strong-field regime. In particular, f(R) theories, which have been widely discuss in a cosmological context, can be constrained through…

Cosmology and Nongalactic Astrophysics · Physics 2012-12-13 Daniela Pérez , Gustavo E. Romero , Santiago E. Perez Bergliaffa

No Kerr-like exact solution has yet been found in Chern-Simons modified gravity. Intrigued by this absence, we study stationary and axisymmetric metrics that could represent the exterior field of spinning black holes. For the standard…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Daniel Grumiller , Nicolas Yunes

Dynamical Chern-Simons gravity is an extension of General Relativity in which the gravitational field is coupled to a scalar field through a parity-violating Chern-Simons term. In this framework, we study perturbations of spherically…

General Relativity and Quantum Cosmology · Physics 2013-12-04 C. Molina , Paolo Pani , Vitor Cardoso , Leonardo Gualtieri

Spinning black holes in dynamical Einstein-Chern-Simons gravity are constructed by directly solving the field equations, without resorting to any perturbative expansion. This model is obtained by adding to the Einstein-Hilbert action a…

General Relativity and Quantum Cosmology · Physics 2018-10-24 Terence Delsate , Carlos Herdeiro , Eugen Radu

Observations of the black hole shadow of supermassive black holes, such as Sagittarius A* at the center of our Milky Way galaxy, allow us to study the properties of black holes and the nature of strong-field gravity. According to the Kerr…

General Relativity and Quantum Cosmology · Physics 2018-11-14 Dimitry Ayzenberg , Nicolas Yunes

The recent gravitational wave observations by the LIGO/Virgo collaboration have allowed the first tests of General Relativity in the extreme gravity regime, when comparable-mass black holes and neutron stars collide. Future space-based…

General Relativity and Quantum Cosmology · Physics 2018-07-03 Alejandro Cardenas-Avendano , Andres F. Gutierrez , Leonardo A. Pachon , Nicolas Yunes

The detection of gravitational waves resulting by the LIGO-Virgo-Kagra collaboration has inaugurated a new era in gravitational physics, providing an opportunity to test general relativity and its modifications in the strong gravity regime.…

General Relativity and Quantum Cosmology · Physics 2023-11-15 Pratik Wagle , Dongjun Li , Yanbei Chen , Nicolas Yunes

We investigate a slowly rotating black hole in four-dimensional extended Chern-Simons modified gravity. We obtain an approximate solution that reduces to the Kerr solution when a coupling constant vanishes. The Chern-Simons correction…

General Relativity and Quantum Cosmology · Physics 2009-11-19 Kohkichi Konno , Toyoki Matsuyama , Satoshi Tanda

In the present work, we consider the possibility of observationally testing Ho\v{r}ava gravity by using the accretion disk properties around slowly rotating black holes of the Kehagias-Sfetsos solution in asymptotically flat spacetimes. The…

General Relativity and Quantum Cosmology · Physics 2011-07-12 Tiberiu Harko , Zoltán Kovács , Francisco S. N. Lobo

Dynamical Chern-Simons (dCS) gravity has been attracting plenty of attentions due to the fact that it is a parity-violating modified theory of gravity that corresponds to a well-posed effective field theory in weak coupling approximation.…

General Relativity and Quantum Cosmology · Physics 2023-05-09 Yuan Meng , Xiao-Mei Kuang , Xi-Jing Wang , Jian-Pin Wu

Chern-Simons modified gravity is a string-theory and loop-quantum-gravity inspired effective theory that modifies General Relativity by adding a parity-violating Pontryagin density to the Einstein-Hilbert action multiplied by a coupling…

General Relativity and Quantum Cosmology · Physics 2010-04-15 Nicolas Yunes , David N. Spergel

We study the tetrad formulation of Chern-Simons (CS) modified gravity, which adds a Pontryagin term to the Einstein-Hilbert action with a spacetime-dependent coupling field. We first verify that CS modified gravity leads to a theory with…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Stephon Alexander , Nicolas Yunes

Dynamical Chern-Simons gravity is an interesting extension of General Relativity, which finds its way in many different contexts, including string theory, cosmological settings and loop quantum gravity. In this theory, the gravitational…

General Relativity and Quantum Cosmology · Physics 2015-03-19 Paolo Pani , Vitor Cardoso , Leonardo Gualtieri

Rapidly rotating black holes are a prime arena for understanding corrections to Einstein's theory of general relativity (GR). We construct solutions for rapidly rotating black holes in dynamical Chern-Simons (dCS) gravity, a useful and…

General Relativity and Quantum Cosmology · Physics 2014-08-25 Leo C. Stein

We consider the basic physical properties of matter forming a thin accretion disc in the static and spherically symmetric space-time metric of the vacuum $f(R)$ modified gravity models. The Lagrangian of the generalized gravity theory is…

General Relativity and Quantum Cosmology · Physics 2008-11-26 C. S. J. Pun , Z. Kovacs , T. Harko

Solar system observations have traditionally allowed for very stringent tests of Einstein's theory of general relativity. We here revisit the possibility of using these observations to constrain gravitational parity violation as…

General Relativity and Quantum Cosmology · Physics 2019-05-22 Yuya Nakamura , Daiki Kikuchi , Kei Yamada , Hideki Asada , Nicolas Yunes

Einstein-dilaton-Gauss-Bonnet gravity is a theoretically well-motivated alternative theory of gravity emerging as a low-energy 4-dimensional model from heterotic string theory. Its rotating black hole solutions are known numerically and can…

General Relativity and Quantum Cosmology · Physics 2017-06-01 Hao Zhang , Menglei Zhou , Cosimo Bambi , Burkhard Kleihaus , Jutta Kunz , Eugen Radu

Dynamical Chern-Simons (DCS) gravity, a typical parity-violating gravitational theory, modifies both the generation and propagation of gravitational waves from general relativity (GR). In this work, we derive the gravitational waveform…

General Relativity and Quantum Cosmology · Physics 2024-05-24 Zhao Li , Jin Qiao , Tan Liu , Rui Niu , Shaoqi Hou , Tao Zhu , Wen Zhao