scholarly journals Dirac perturbations on Schwarzschild–anti–de Sitter spacetimes: Generic boundary conditions and new quasinormal modes

2017 ◽  
Vol 96 (10) ◽  
Author(s):  
Mengjie Wang ◽  
Carlos Herdeiro ◽  
Jiliang Jing
Keyword(s):  
Boundary Conditions ◽  
Quasinormal Modes ◽  
De Sitter ◽  
Generic Boundary

scholarly journals Maxwell perturbations in a cavity with Robin boundary conditions: two branches of modes with spectrum bifurcation on Schwarzschild black holes

2021 ◽  
Vol 81 (12) ◽  
Author(s):  
Yunhe Lei ◽  
Mengjie Wang ◽  
Jiliang Jing
Keyword(s):  
Black Holes ◽  
Boundary Conditions ◽  
Energy Flux ◽  
Maxwell Equations ◽  
Quasinormal Modes ◽  
De Sitter ◽  
Angular Momentum Quantum Number ◽  
Ads Black Holes ◽  
Maxwell Fields ◽  
Robin Boundary

AbstractWe perform a systematic study of the Maxwell quasinormal spectrum in a mirror-like cavity following the generic Robin type vanishing energy flux principle, by starting with the Schwarzschild black holes in this paper. It is shown that, for black holes in a cavity, the vanishing energy flux principle leads to two different sets of boundary conditions. By solving the Maxwell equations with these two boundary conditions both analytically and numerically, we observe two distinct sets of modes. This indicates that the vanishing energy flux principle may be applied not only to asymptotically anti-de Sitter (AdS) black holes but also to black holes in a cavity. In the analytic calculations, the imaginary part of the Maxwell quasinormal modes are derived analytically for both boundary conditions, which match well with the numeric results. While in the numeric calculations, we complete a thorough study on the two sets of the Maxwell spectrum by varying the mirror radius $$r_m$$ r m , the angular momentum quantum number $$\ell $$ ℓ , and the overtone number N. In particular, we proclaim that the Maxwell spectrum may bifurcate for both modes when the mirror is placed around the black hole event horizon, which is analogous to the spectrum bifurcation effects found for the Maxwell fields on asymptotically AdS black holes. This observation provides another example to exhibit the similarity between black holes in a cavity and the AdS black holes.

scholarly journals Maxwell quasinormal modes on a global monopole Schwarzschild-anti-de Sitter black hole with Robin boundary conditions

2021 ◽  
Vol 81 (5) ◽  
Author(s):  
Mengjie Wang ◽  
Zhou Chen ◽  
Qiyuan Pan ◽  
Jiliang Jing
Keyword(s):  
Black Hole ◽  
Boundary Conditions ◽  
Energy Flux ◽  
Maxwell Equations ◽  
Normal Modes ◽  
Quasinormal Modes ◽  
Low Frequency ◽  
Global Monopole ◽  
De Sitter ◽  
Small Black Hole

AbstractWe generalize our previous studies on the Maxwell quasinormal modes around Schwarzschild-anti-de-Sitter black holes with Robin type vanishing energy flux boundary conditions, by adding a global monopole on the background. We first formulate the Maxwell equations both in the Regge–Wheeler–Zerilli and in the Teukolsky formalisms and derive, based on the vanishing energy flux principle, two boundary conditions in each formalism. The Maxwell equations are then solved analytically in pure anti-de Sitter spacetimes with a global monopole, and two different normal modes are obtained due to the existence of the monopole parameter. In the small black hole and low frequency approximations, the Maxwell quasinormal modes are solved perturbatively on top of normal modes by using an asymptotic matching method, while beyond the aforementioned approximation, the Maxwell quasinormal modes are obtained numerically. We analyze the Maxwell quasinormal spectrum by varying the angular momentum quantum number $$\ell $$ ℓ , the overtone number N, and in particular, the monopole parameter $$8\pi \eta ^2$$ 8 π η 2 . We show explicitly, through calculating quasinormal frequencies with both boundary conditions, that the global monopole produces the repulsive force.

scholarly journals Quasinormal modes of dS and AdS black holes: Feedforward neural network method

2021 ◽  
pp. 2150154
Author(s):  
Ali Övgün ◽  
İzzet Sakallı ◽  
Halil Mutuk
Keyword(s):  
Neural Network ◽  
Black Holes ◽  
Boundary Conditions ◽  
Quasinormal Modes ◽  
Scalar Fields ◽  
Feedforward Neural Network ◽  
De Sitter ◽  
Neural Network Method ◽  
Ads Black Holes ◽  
Network Method

In this paper, we show how the quasinormal modes (QNMs) arise from the perturbations of massive scalar fields propagating in the curved background by using the artificial neural networks. To this end, we architect a special algorithm for the feedforward neural network method (FNNM) to compute the QNMs complying with the certain types of boundary conditions. To test the reliability of the method, we consider two black hole spacetimes whose QNMs are well known: [Formula: see text] pure de Sitter (dS) and five-dimensional Schwarzschild anti-de Sitter (AdS) black holes. Using the FNNM, the QNMs of are computed numerically. It is shown that the obtained QNMs via the FNNM are in good agreement with their former QNM results resulting from the other methods. Therefore, our method of finding the QNMs can be used for other curved spacetimes that obey the same boundary conditions.

scholarly journals Massive Dirac quasinormal modes in Schwarzschild–de Sitter black holes: Anomalous decay rate and fine structure

2021 ◽  
Vol 103 (6) ◽  
Author(s):  
Almendra Aragón ◽  
Ramón Bécar ◽  
P. A. González ◽  
Yerko Vásquez
Keyword(s):  
Black Holes ◽  
Fine Structure ◽  
Decay Rate ◽  
Quasinormal Modes ◽  
De Sitter

scholarly journals Geometries with mismatched branes

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
Andreas Karch ◽  
Lisa Randall
Keyword(s):  
Boundary Conditions ◽  
Effective Action ◽  
Cosmological Models ◽  
Time Dependent ◽  
De Sitter ◽  
Stabilization Mechanism ◽  
New Class ◽  
Vacuum Solutions ◽  
Single Coordinate

Abstract We study Randall-Sundrum two brane setups with mismatched brane tensions. For the vacuum solutions, boundary conditions demand that the induced metric on each of the branes is either de Sitter, Anti-de Sitter, or Minkowski. For incompatible boundary conditions, the bulk metric is necessarily time-dependent. This introduces a new class of time-dependent solutions with the potential to address cosmological issues and provide alternatives to conventional inflationary (or contracting) scenarios. We take a first step in this paper toward such solutions. One important finding is that the resulting solutions can be very succinctly described in terms of an effective action involving only the induced metric on either one of the branes and the radion field. But the full geometry cannot necessarily be simply described with a single coordinate patch. We concentrate here on the time- dependent solutions but argue that supplemented with a brane stabilization mechanism one can potentially construct interesting cosmological models this way. This is true both with and without a brane stabilization mechanism.

scholarly journals Quasinormal modes of (anti-)de Sitter black holes in the 1/D expansion

2015 ◽  
Vol 2015 (4) ◽  
Author(s):  
Roberto Emparan ◽  
Ryotaku Suzuki ◽  
Kentaro Tanabe
Keyword(s):  
Black Holes ◽  
Quasinormal Modes ◽  
De Sitter
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