scholarly journals A family of solutions to the inverse problem in gravitation: building a theory around a metric

2021 ◽  
Vol 53 (1) ◽  
Author(s):  
Arthur G. Suvorov
Keyword(s):  
Inverse Problem ◽  
Black Hole ◽  
Vacuum Solution ◽  
Equations Of Motion ◽  
Standard Approach ◽  
Scalar Tensor Theory ◽  
Tensor Theory ◽  
Explicit Theory ◽  
Black Hole Spacetime

AbstractA method is presented to construct a particular, non-minimally coupled scalar–tensor theory such that a given metric is an exact vacuum solution in that theory. In contrast to the standard approach in studies of gravitational dynamics, where one begins with an action and then solves the equations of motion, this approach allows for an explicit theory to be built around some pre-specified geometry. Starting from a parameterized black hole spacetime with generic, non-Kerr hairs, it is shown how an overarching family of theories can be designed to fit the metric exactly.

scholarly journals Extremal Cosmological Black Holes in Horndeski Gravity and the Anti-Evaporation Regime

Universe ◽  
2020 ◽  
Vol 6 (11) ◽  
pp. 210
Author(s):  
Ismael Ayuso ◽  
Diego Sáez-Chillón Gómez
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Cosmological Constant ◽  
Linear Order ◽  
Scalar Tensor Theory ◽  
De Sitter ◽  
Tensor Theory ◽  
Effective Cosmological Constant ◽  
Cosmological Black Holes ◽  
Extremal Black Holes

Extremal cosmological black holes are analysed in the framework of the most general second order scalar-tensor theory, the so-called Horndeski gravity. Such extremal black holes are a particular case of Schwarzschild-De Sitter black holes that arises when the black hole horizon and the cosmological one coincide. Such metric is induced by a particular value of the effective cosmological constant and is known as Nariai spacetime. The existence of this type of solutions is studied when considering the Horndeski Lagrangian and its stability is analysed, where the so-called anti-evaporation regime is studied. Contrary to other frameworks, the radius of the horizon remains stable for some cases of the Horndeski Lagrangian when considering perturbations at linear order.

scholarly journals ON THE ENTROPY OF MINIMALLY COUPLED AND NONMINIMALLY COUPLED GRAVITIES

1996 ◽  
Vol 11 (25) ◽  
pp. 2037-2045 ◽  
Author(s):  
JEONG-WON HO ◽  
YONGDUK KIM ◽  
YOUNG-JAI PARK
Keyword(s):  
Black Hole ◽  
Thermodynamic Properties ◽  
Conformal Transformation ◽  
Low Energy ◽  
Bosonic String ◽  
Effective Theory ◽  
Scalar Tensor Theory ◽  
Tensor Theory ◽  
Theory Of Gravity ◽  
Electrically Charged

We investigate whether the gravitational thermodynamic properties of the scalar-tensor theory of gravity are affected by the conformal transformation or not. As an explicit example, we consider an electrically charged static spherical black hole in four-dimensional low energy effective theory of bosonic string.

scholarly journals Black holes in active galactic nuclei

2009 ◽  
Vol 5 (S261) ◽  
pp. 260-268
Author(s):  
M. J. Valtonen ◽  
S. Mikkola ◽  
D. Merritt ◽  
A. Gopakumar ◽  
H. J. Lehto ◽  
...  
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Strong Field ◽  
Equations Of Motion ◽  
Binary Black Holes ◽  
Time Dynamic ◽  
Black Hole Spacetime ◽  
First Time ◽  
Black Hole Masses

AbstractSupermassive black holes are common in centers of galaxies. Among the active galaxies, quasars are the most extreme, and their black hole masses range as high as to 6⋅1010M⊙. Binary black holes are of special interest but so far OJ287 is the only confirmed case with known orbital elements. In OJ287, the binary nature is confirmed by periodic radiation pulses. The period is twelve years with two pulses per period. The last four pulses have been correctly predicted with the accuracy of few weeks, the latest in 2007 with the accuracy of one day. This accuracy is high enough that one may test the higher order terms in the Post Newtonian approximation to General Relativity. The precession rate per period is 39°.1 ± 0°.1, by far the largest rate in any known binary, and the (1.83 ± 0.01)⋅1010M⊙primary is among the dozen biggest black holes known. We will discuss the various Post Newtonian terms and their effect on the orbit solution. The over 100 year data base of optical variations in OJ287 puts limits on these terms and thus tests the ability of Einstein's General Relativity to describe, for the first time, dynamic binary black hole spacetime in the strong field regime. The quadrupole-moment contributions to the equations of motion allows us to constrain the ‘no-hair’ parameter to be 1.0 ± 0.3 which supports the black hole no-hair theorem within the achievable precision.

scholarly journals Wave-like spatially homogeneous models of Stackel spacetimes (3.1) type in the scalar-tensor theory of gravity

2020 ◽  
Vol 17 (12) ◽  
pp. 2050184
Author(s):  
Evgeny Osetrin ◽  
Konstantin Osetrin ◽  
Altair Filippov ◽  
Ilya Kirnos
Keyword(s):  
Eikonal Equation ◽  
Separation Of Variables ◽  
Equations Of Motion ◽  
Scalar Tensor Theory ◽  
Tensor Theory ◽  
Test Particles ◽  
Petrov Classification ◽  
Homogeneous Models ◽  
Theory Of Gravitation ◽  
Spatially Homogeneous

All classes of spatially homogeneous spacetime models in the generalized scalar–tensor theory of gravitation are found to allow the integration of the equations of motion of test particles and the eikonal equation by the method of separation of variables by type (3.1). Three classes of exact solutions are obtained that relate to Shapovalov wave-like spacetime models. The resulting spacetime models are of types IV, VI and VII according to the Bianchi classification and type N according to Petrov classification.

scholarly journals Gravitational memory effects and Bondi-Metzner-Sachs symmetries in scalar-tensor theories

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Shaoqi Hou ◽  
Zong-Hong Zhu
Keyword(s):  
General Relativity ◽  
Angular Momentum ◽  
Evolution Equations ◽  
Equations Of Motion ◽  
Memory Effects ◽  
Scalar Tensor Theory ◽  
Null Infinity ◽  
Infinite Dimensional ◽  
Tensor Theory ◽  
Bondi Mass

Abstract The relation between gravitational memory effects and Bondi-Metzner-Sachs symmetries of the asymptotically flat spacetimes is studied in the scalar-tensor theory. For this purpose, the solutions to the equations of motion near the future null infinity are obtained in the generalized Bondi-Sachs coordinates with a suitable determinant condition. It turns out that the Bondi-Metzner-Sachs group is also a semi-direct product of an infinite dimensional supertranslation group and the Lorentz group as in general relativity. There are also degenerate vacua in both the tensor and the scalar sectors in the scalar-tensor theory. The supertranslation relates the vacua in the tensor sector, while in the scalar sector, it is the Lorentz transformation that transforms the vacua to each other. So there are the tensor memory effects similar to the ones in general relativity, and the scalar memory effect, which is new. The evolution equations for the Bondi mass and angular momentum aspects suggest that the null energy fluxes and the angular momentum fluxes across the null infinity induce the transition among the vacua in the tensor and the scalar sectors, respectively.

scholarly journals Strong cosmic censorship in near-extremal Kerr-Sen-de Sitter spacetime

2021 ◽  
Vol 81 (11) ◽  
Author(s):  
Ming Zhang ◽  
Jie Jiang
Keyword(s):  
Black Hole ◽  
Scalar Field ◽  
Equations Of Motion ◽  
Cosmic Censorship ◽  
Cauchy Horizon ◽  
De Sitter ◽  
Sitter Spacetime ◽  
Resonant Modes ◽  
Strong Cosmic Censorship ◽  
Black Hole Spacetime

AbstractIn this work, we first calculate equations of motion for particles in the Kerr-Sen-de Sitter black hole spacetime. Then, in the eikonal regime, we analytically obtain the quasi-normal resonant modes of massless neutral scalar field perturbation and find its imaginary part to be characterized by the surface gravity of a near-extremal Kerr-Sen-de Sitter black hole with the Cauchy horizon approaching the event horizon. We further show that the Penrose strong cosmic censorship conjecture is thus respected in this spacetime with dilaton scalar field and axion pseudoscalar field.

scholarly journals ON THE DETECTION OF SCALAR HAIR

2001 ◽  
Vol 16 (19) ◽  
pp. 1223-1228 ◽  
Author(s):  
NARAYAN BANERJEE ◽  
SOMASRI SEN ◽  
NARESH DADHICH
Keyword(s):  
Black Hole ◽  
Scalar Field ◽  
Conformal Transformation ◽  
Scalar Tensor Theory ◽  
Tensor Theory ◽  
Scalar Hair

It is shown that the conclusion regarding the existence of a scalar hair for a black hole in a non-minimally coupled self-interacting scalar–tensor theory can be drawn from that for a scalar field minimally coupled to gravity by means of a conformal transformation.

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