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The low-energy limit of string theory contains an anomaly-canceling correction to the Einstein-Hilbert action, which defines an effective theory: Chern-Simons (CS) modified gravity. The CS correction consists of the product of a scalar…

General Relativity and Quantum Cosmology · Physics 2009-10-29 Nicolas Yunes , Frans Pretorius

Chern-Simons (CS) modified gravity is an extension to general relativity (GR) in which the metric is coupled to a scalar field, resulting in modified Einstein field equations. In the dynamical theory, the scalar field is itself sourced by…

High Energy Astrophysical Phenomena · Physics 2011-12-16 Yacine Ali-Haïmoud , Yanbei Chen

The Chern-Simons (CS) gravity is a modified theory of Einstein's general relativity (GR). The CS theory arises from the low energy limit of string theory which involves anomaly correction to the Einstein-Hilbert action. The CS term is given…

General Relativity and Quantum Cosmology · Physics 2023-04-12 G. G. L. Nashed , Shin'ichi Nojiri

[abridged] Chern-Simons (CS) modified gravity is a 4D effective theory that descends both from string theory and loop quantum gravity, and that corrects the Einstein-Hilbert action by adding the product of a scalar field and the…

General Relativity and Quantum Cosmology · Physics 2009-11-06 Carlos F. Sopuerta , Nicolas Yunes

The Chern-Simons amended gravity theory appears as a low-energy effective theory of string theory. The effective theory includes an anomaly-cancelation correction to the Einstein-Hilbert action. The Chern-Simons expression consists of the…

General Relativity and Quantum Cosmology · Physics 2023-02-22 G. G. L. Nashed , Shin'ichi Nojiri

One of the most crucial areas of gravity research, after the direct observation of gravitational waves, is the possible modification of General Relativity at ultraviolet and infrared scales. In particular, the possibility of parity…

General Relativity and Quantum Cosmology · Physics 2023-03-29 G. G. L. Nashed , S. Capozziello

We consider the nondynamical Chern-Simons (CS) modification to General Relativity (GR) in the framework of the Einstein-Cartan formulation, as providing a way to incorporate a slowly rotating Kerr black hole in the space of solutions. Our…

General Relativity and Quantum Cosmology · Physics 2017-08-23 Mauro Cambiaso , Luis F. Urrutia

Observations of the continuum spectrum emitted by accretion disks around black holes allows us to infer their properties, including possibly whether black holes are described by the Kerr metric. Some modified gravity theories do not admit…

General Relativity and Quantum Cosmology · Physics 2017-05-22 Dimitry Ayzenberg , Nicolas Yunes

We investigate the possibility to distinguish the small-coupling, slow-rotation black hole solution of Chern-Simons (CS) gravity from the Kerr solution. We develop simulations of electromagnetic observables in the vicinity of CS and Kerr…

High Energy Astrophysical Phenomena · Physics 2015-06-17 F. H. Vincent

Rapidly rotating black hole solutions in theories beyond general relativity play a key role in experimental gravity, as they allow us to compute observables in extreme spacetimes that deviate from the predictions of general relativity. Such…

General Relativity and Quantum Cosmology · Physics 2016-11-29 Robert McNees , Leo C. Stein , Nicolás Yunes

Testing deviation of GR is one of the main goals of the proposed {\emph{Laser Interferometer Space Antenna}}, a space-based gravitational-wave observatory. For the first time, we consistently compute the generation of gravitational waves…

General Relativity and Quantum Cosmology · Physics 2014-11-20 Nicolas Yunes , C. F. Sopuerta

Einstein-scalar-Gauss-Bonnet gravity has recently been known to exhibit spontaneous scalarization. In the presence of the Gauss-Bonnet term the no-hair theorem can be evaded and novel black hole solutions with non-trivial scalar fields have…

General Relativity and Quantum Cosmology · Physics 2021-04-12 Mohaddese Heydari-Fard , Hamid Reza Sepangi

Solutions pertaining to a Kerr black hole with a flat horizon undergoing gradual rotation are explored in the context of gravitational theories modified by dynamical Chern-Simons terms with cylindrical metrics, which approach asymptotically…

General Relativity and Quantum Cosmology · Physics 2023-11-16 G. G. L. Nashed , Kazuharu Bamba

We discuss a Chern-Simons (CS) scalar field around a rapidly rotating black hole in dynamical CS modified gravity. The CS correction can be obtained perturbatively by considering the Kerr spacetime to be the background. We obtain the CS…

General Relativity and Quantum Cosmology · Physics 2014-09-10 Kohkichi Konno , Rohta Takahashi

Dynamical Chern-Simons (dCS) gravity is a promising extension of general relativity (GR), arising naturally from the low-energy limit of some string motivated theories. Even though dCS possesses an additional scalar degree of freedom,…

General Relativity and Quantum Cosmology · Physics 2018-11-07 Caio F. B. Macedo

Dynamical Chern-Simons (DCS) modified gravity is an attractive, yet relatively unexplored, candidate to an alternative theory of gravity. The DCS correction couples a dynamical scalar field to the gravitational field. In this framework, we…

General Relativity and Quantum Cosmology · Physics 2014-11-20 V. Cardoso , L. Gualtieri

In the Einstein-Cartan formulation, an iterative procedure to find solutions in non-dynamical Chern-Simons (CS) gravity in vacuum is proposed. The iterations, in powers of a small parameter $\beta$ which codifies the CS coupling, start from…

General Relativity and Quantum Cosmology · Physics 2010-12-21 Mauro Cambiaso , Luis F. Urrutia

Recently, Kumar and Ghosh have derived Kerr-like rotating black hole solutions in the framework of four-dimensional Einstein-Gauss-Bonnet theory of gravity and investigated the black hole shadow. Using the steady-state Novikov-Thorne model,…

General Relativity and Quantum Cosmology · Physics 2021-06-16 Mohaddese Heydari-Fard , Malihe Heydari-Fard , Hamid Reza Sepangi

The detection of gravitational waves from compact binary mergers by the LIGO/Virgo collaboration has, for the first time, allowed us to test relativistic gravity in its strong, dynamical and nonlinear regime, thus opening a new arena to…

General Relativity and Quantum Cosmology · Physics 2022-06-16 Pratik Wagle , Nicolas Yunes , Hector O. Silva

The chiral scalar-tensor theory is an extension of the Chern-Simons modified gravity by introducing couplings between the first and second derivatives of the scalar field and parity-violating spacetime curvatures. A key feature of this…

General Relativity and Quantum Cosmology · Physics 2025-04-15 Ze-Kai Yu , Lei Liu , Tao Zhu
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