scholarly journals Photon regions and shadows of Kerr-Newman-NUT black holes with a cosmological constant

2014 ◽  
Vol 89 (12) ◽  
Author(s):  
Arne Grenzebach ◽  
Volker Perlick ◽  
Claus Lämmerzahl
Keyword(s):  
Black Holes ◽  
Cosmological Constant ◽  
Photon Regions

scholarly journals Photon regions and shadows of accelerated black holes

2015 ◽  
Vol 24 (09) ◽  
pp. 1542024 ◽  
Author(s):  
Arne Grenzebach ◽  
Volker Perlick ◽  
Claus Lämmerzahl
Keyword(s):  
Black Holes ◽  
Cosmological Constant ◽  
Boundary Curve ◽  
Kerr Metric ◽  
Axially Symmetric ◽  
De Sitter ◽  
Acceleration Parameter ◽  
Type D ◽  
Analytical Formulas ◽  
Photon Regions

In an earlier paper, we have analytically determined the photon regions and the shadows of black holes of the Plebański class of metrics which are also known as the Kerr–Newman–NUT–(anti-)de Sitter metrics. These metrics are characterized by six parameters: Mass, spin, electric and magnetic charges, gravitomagnetic NUT charge and the cosmological constant. Here, we extend this analysis to the Plebański–Demiański class of metrics which contains, in addition to these six parameters, the so-called acceleration parameter. All these metrics are axially symmetric and stationary type D solutions to the Einstein–Maxwell equations with a cosmological constant. We derive analytical formulas for the photon regions (i.e. for the regions that contain spherical lightlike geodesics) and for the boundary curve of the shadow as it is seen by an observer at Boyer–Lindquist coordinates (rO, ϑO) in the domain of outer communication. Whereas all relevant formulas are derived for the whole Plebański–Demiański class, we concentrate on the accelerated Kerr metric (i.e. only mass, spin and acceleration parameter are different from zero) when discussing the influence of the acceleration parameter on the photon region and on the shadow in terms of pictures. The accelerated Kerr metric is also known as the rotating C-metric. We discuss how our analytical formulas can be used for calculating the horizontal and vertical angular diameters of the shadow and we estimate these values for the black holes at the center of our Galaxy and at the center of M87.

scholarly journals Bootstrapped Newtonian Cosmology and the Cosmological Constant Problem

Symmetry ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 358
Author(s):  
Roberto Casadio ◽  
Andrea Giusti
Keyword(s):  
Black Holes ◽  
Cosmological Constant ◽  
Quantum Cosmology ◽  
Quantum Physics ◽  
Gravitational Interaction ◽  
Newtonian Gravity ◽  
Cosmological Constant Problem ◽  
Newtonian Cosmology ◽  
Natural Solution ◽  
The Impact

Bootstrapped Newtonian gravity was developed with the purpose of estimating the impact of quantum physics in the nonlinear regime of the gravitational interaction, akin to corpuscular models of black holes and inflation. In this work, we set the ground for extending the bootstrapped Newtonian picture to cosmological spaces. We further discuss how such models of quantum cosmology can lead to a natural solution to the cosmological constant problem.

scholarly journals Black holes and other spherical solutions in quadratic gravity with a cosmological constant

2021 ◽  
Vol 103 (6) ◽  
Author(s):  
V. Pravda ◽  
A. Pravdová ◽  
J. Podolský ◽  
R. Švarc
Keyword(s):  
Black Holes ◽  
Cosmological Constant ◽  
Quadratic Gravity

scholarly journals Effective Field Theory, Black Holes, and the Cosmological Constant

1999 ◽  
Vol 82 (25) ◽  
pp. 4971-4974 ◽  
Author(s):  
Andrew G. Cohen ◽  
David B. Kaplan ◽  
Ann E. Nelson
Keyword(s):  
Field Theory ◽  
Black Holes ◽  
Cosmological Constant ◽  
Effective Field Theory ◽  
Effective Field

scholarly journals Central charges for AdS black holes

2021 ◽  
Author(s):  
Malcolm Perry ◽  
Maria J Rodriguez
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Cosmological Constant ◽  
Central Charge ◽  
Negative Cosmological Constant ◽  
Ads Black Holes ◽  
Kerr Black Holes ◽  
Distinguishing Features ◽  
Area Law ◽  
Cardy Formula

Abstract Nontrivial diffeomorphisms act on the horizon of a generic 4D black holes and create distinguishing features referred to as soft hair. Amongst these are a left-right pair of Virasoro algebras with associated charges that reproduce the Bekenstein-Hawking entropy for Kerr black holes. In this paper we show that if one adds a negative cosmological constant, there is a similar set of infinitesimal diffeomorphisms that act non-trivially on the horizon. The algebra of these diffeomorphisms gives rise to a central charge. Adding a boundary counterterm, justified to achieve integrability, leads to well-defined central charges with cL = cR. The macroscopic area law for Kerr-AdS black holes follows from the assumption of a Cardy formula governing the black hole microstates.

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 Action and entropy of black holes in spacetimes with a cosmological constant

1998 ◽  
Vol 15 (9) ◽  
pp. 2783-2793 ◽  
Author(s):  
Rong-Gen Cai ◽  
Jeong-Young Ji ◽  
Kwang-Sup Soh
Keyword(s):  
Black Holes ◽  
Cosmological Constant
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