scholarly journals Scalar Perturbations of Black Holes in the f(R)=R−2αR Model

Universe ◽  
2022 ◽  
Vol 8 (1) ◽  
pp. 47
Author(s):  
Ping Li ◽  
Rui Jiang ◽  
Jian Lv ◽  
Xianghua Zhai
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Scalar Field ◽  
Critical Frequency ◽  
Amplification Factor ◽  
Quasinormal Modes ◽  
Spherically Symmetric ◽  
Third Order ◽  
Charged Scalar ◽  
The Time Domain

In this paper, we study the perturbations of the charged static spherically symmetric black holes in the f(R)=R−2αR model by a scalar field. We analyze the quasinormal modes spectrum, superradiant modes, and superradiant instability of the black holes. The frequency of the quasinormal modes is calculated in the frequency domain by the third-order WKB method, and in the time domain by the finite difference method. The results by the two methods are consistent and show that the black hole stabilizes quicker for larger α satisfying the horizon condition. We then analyze the superradiant modes when the massive charged scalar field is scattered by the black hole. The frequency of the superradiant wave satisfies ω∈(μ2,ωc), where μ is the mass of the scalar field, and ωc is the critical frequency of the superradiance. The amplification factor is also calculated by numerical method. Furthermore, the superradiant instability of the black hole is studied analytically, and the results show that there is no superradiant instability for such a system.

scholarly journals Massive scalar field quasinormal modes of a Schwarzschild black hole surrounded by quintessence

Open Physics ◽  
2008 ◽  
Vol 6 (2) ◽  
Author(s):  
Chunrui Ma ◽  
Yuanxing Gui ◽  
Wei Wang ◽  
Fujun Wang
Keyword(s):  
Black Hole ◽  
Scalar Field ◽  
Quasinormal Modes ◽  
Massless Scalar ◽  
Massless Scalar Field ◽  
Massive Scalar ◽  
Schwarzschild Black Hole ◽  
Third Order ◽  
Massive Scalar Field ◽  
Absolute Value

AbstractWe present the quasinormal frequencies of the massive scalar field in the background of a Schwarzchild black hole surrounded by quintessence with the third-order WKB method. The mass of the scalar field u plays an important role in studying the quasinormal frequencies, the real part of the frequencies increases linearly as mass of the field u increases, while the imaginary part in absolute value decreases linearly which leads to damping more slowly than the massless scalar field. The frequencies have a limited value, so it is easier to detect the quasinormal modes. Moreover, owing to the presence of the quintessence, the massive scalar field damps more slowly.

scholarly journals On Quasinormal Modes for Scalar Perturbations of Static Spherically Symmetric Black Holes in Nash Embedding Framework

2017 ◽  
Vol 2017 ◽  
pp. 1-10
Author(s):  
Sergio C. Ulhoa ◽  
Ronni G. G. Amorim ◽  
Abraão J. S. Capistrano
Keyword(s):  
Black Holes ◽  
Quasinormal Modes ◽  
Wkb Approximation ◽  
Spherically Symmetric ◽  
Third Order ◽  
Five Dimensions ◽  
The Third ◽  
Bulk Space ◽  
Scalar Perturbations

In this paper we investigate scalar perturbations of black holes embedded in a five-dimensional bulk space. The quasinormal frequencies of such black holes are calculated using the third order of Wentzel, Kramers, and Brillouin (WKB) approximation for scalar perturbations. The high overtones of quasinormal modes indicate a resonant-like set of black holes suggesting a serious constraint of embedding models in five dimensions.

scholarly journals Quasinormal modes of hot, cold and bald Einstein–Maxwell-scalar black holes

2021 ◽  
Vol 81 (2) ◽  
Author(s):  
Jose Luis Blázquez-Salcedo ◽  
Carlos A. R. Herdeiro ◽  
Sarah Kahlen ◽  
Jutta Kunz ◽  
Alexandre M. Pombo ◽  
...  
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Scalar Field ◽  
Unstable Mode ◽  
Quasinormal Modes ◽  
Coupling Function ◽  
Quartic Coupling ◽  
Linear Mode ◽  
Mode Stability ◽  
Black Hole Solutions

AbstractEinstein–Maxwell-scalar models allow for different classes of black hole solutions, depending on the non-minimal coupling function $$f(\phi )$$ f ( ϕ ) employed, between the scalar field and the Maxwell invariant. Here, we address the linear mode stability of the black hole solutions obtained recently for a quartic coupling function, $$f(\phi )=1+\alpha \phi ^4$$ f ( ϕ ) = 1 + α ϕ 4 (Blázquez-Salcedo et al. in Phys. Lett. B 806:135493, 2020). Besides the bald Reissner–Nordström solutions, this coupling allows for two branches of scalarized black holes, termed cold and hot, respectively. For these three branches of black holes we calculate the spectrum of quasinormal modes. It consists of polar scalar-led modes, polar and axial electromagnetic-led modes, and polar and axial gravitational-led modes. We demonstrate that the only unstable mode present is the radial scalar-led mode of the cold branch. Consequently, the bald Reissner–Nordström branch and the hot scalarized branch are both mode-stable. The non-trivial scalar field in the scalarized background solutions leads to the breaking of the degeneracy between axial and polar modes present for Reissner–Nordström solutions. This isospectrality is only slightly broken on the cold branch, but it is strongly broken on the hot branch.

scholarly journals Scalar modes, spontaneous scalarization and circular null-geodesics of black holes in scalar-Gauss–Bonnet gravity

2020 ◽  
Vol 29 (11) ◽  
pp. 2041006 ◽  
Author(s):  
Caio F. B. Macedo
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Scalar Field ◽  
Quasinormal Modes ◽  
Mode Analysis ◽  
Bonnet Gravity ◽  
Black Hole Binaries ◽  
The Impact ◽  
Black Hole Solutions

In general relativity, astrophysical black holes (BHs) are simple objects, described by just their mass and spin. These simple solutions are not exclusive to general relativity, as they also appear in theories that allow for an extra scalar degree of freedom. Recently, it was shown that some theories which couple a scalar field with the Gauss–Bonnet invariant can have the same classic black hole solutions from general relativity as well as hairy BHs. These scalarized solutions can be stable, having an additional “charge” term that has an impact on the gravitational-wave emission by black hole binaries. In this paper, we overview black hole solutions in scalar-Gauss–Bonnet gravity, considering self-interacting terms for the scalar field. We present the mode analysis for the monopolar and dipolar perturbations around the Schwarzschild black hole in scalar-Gauss–Bonnet, showing the transition between stable and unstable solutions. We also present the time-evolution of scalar Gaussian wave packets, analyzing the impact of the scalar-Gauss–Bonnet term in their evolution. We then present some scalarized solutions, showing that nonlinear coupling functions and self-interacting terms can stabilize them. Finally, we compute the light-ring frequency and the Lyapunov exponent, which possibly estimate the black hole quasinormal modes in the eikonal limit.

scholarly journals Scalar and electromagnetic quasinormal modes of an extended black hole in F(R) gravity

2015 ◽  
Vol 30 (05) ◽  
pp. 1550012 ◽  
Author(s):  
Saneesh Sebastian ◽  
V. C. Kuriakose
Keyword(s):  
Black Hole ◽  
Scalar Field ◽  
Imaginary Part ◽  
Quasinormal Modes ◽  
Quasinormal Mode ◽  
Wkb Method ◽  
Third Order ◽  
Absolute Value ◽  
The Third ◽  
The Absolute

In this paper, we study the scalar and electromagnetic perturbations of an extended black hole in F(R) gravity. The quasinormal modes in two cases are evaluated and studied their behavior by plotting graphs in each case. To study the quasinormal mode, we use the third-order WKB method. The present study shows that the absolute value of imaginary part of complex quasinormal modes increases in both cases, thus the black hole is stable against these perturbations. As the mass of the scalar field increases the imaginary part of the frequency decreases. Thus, damping slows down with increasing mass of the scalar field.

scholarly journals SPACING OF THE ENTROPY SPECTRUM FOR KS BLACK HOLE IN HOŘAVA–LIFSHITZ GRAVITY

2011 ◽  
Vol 26 (02) ◽  
pp. 151-159 ◽  
Author(s):  
M. R. SETARE ◽  
D. MOMENI
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Mass Parameter ◽  
Quasinormal Modes ◽  
Surface Gravity ◽  
Spherically Symmetric ◽  
Entropy Spectrum ◽  
Adiabatic Invariance ◽  
Fundamental Parameters ◽  
Symmetric Spacetime

In this paper we present the spectrum of entropy/area for Kehagias–Sfetsos (KS) black hole in Hořava–Lifshitz (HL) gravity via quasinormal modes (QNM) approach. We show that in the massive case, the mass parameter μ disappears in the entropy spectrum and the quasinormal modes are modified by a term proportional to the mass square term. Our calculations show that the charge-like parameter [Formula: see text] appears in the surface gravity and our calculations can be applied to any spherically symmetric spacetime which has only one physically acceptable horizon. Our main difference between our calculations and what was done in Ref. 1 is that we explicitly calculated the portion of charge and mass on the surface gravity and consequently in the QNM expression. Since the imaginary part of the QNM is related to the adiabatic invariance of the system and also to the entropy, surprisingly the mass parameter does not appear in the entropy spectrum. Our conclusion supported by some acclaims about the scalar field parameters (charges) cannot change the fundamental parameters in the four-dimensional black holes.

Massive scalar field quasinormal modes of a black hole in the deformed Hořava-Lifshitz gravity

Open Physics ◽  
2012 ◽  
Vol 10 (1) ◽  
Author(s):  
ChunYan Wang ◽  
YaJun Gao
Keyword(s):  
Black Hole ◽  
Scalar Field ◽  
Quasinormal Modes ◽  
Massive Scalar ◽  
Coupling Constant ◽  
Field Mass ◽  
Third Order ◽  
Massive Scalar Field ◽  
The Third ◽  
Black Hole Spacetime

AbstractWe calculated the quasinormalmodes ofmassive scalar field of a black hole in the deformed Hořava-Lifshitz gravity with coupling constant λ = 1, using the third-order WKB approximation. Our results show that when the scalar field mass increases, the oscillation frequency increases while the damping decreases. And we find that the imaginary parts are almost linearly related to the real parts, the behaviors are very similar to that in the Reissner-Nordström black hole spacetime. These information will help us understand more about the Hořava-Lifshitz gravity.

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