scholarly journals THE REAL SCALAR FIELD EQUATION FOR NARIAI BLACK HOLE IN THE 5D SCHWARZSCHILD–DE SITTER BLACK STRING SPACE

2007 ◽  
Vol 22 (24) ◽  
pp. 4451-4465 ◽  
Author(s):  
MOLIN LIU ◽  
HONGYA LIU ◽  
CHUNXIAO WANG ◽  
YONGLI PING
Keyword(s):  
Black Hole ◽  
Field Equation ◽  
Scalar Field ◽  
Massless Scalar ◽  
Massless Scalar Field ◽  
De Sitter ◽  
Black String ◽  
Transmission Coefficients ◽  
Scalar Field Equation ◽  
Continuous Potential

The Nariai black hole, whose two horizons are lying close to each other, is an extreme and important case in the research of black hole. In this paper we study the evolution of a massless scalar field scattered around in 5D Schwarzschild–de Sitter black string space. Using the method shown by Brevik and Simonsen (2001) we solve the scalar field equation as a boundary value problem, where real boundary condition is employed. Then with convenient replacement of the 5D continuous potential by square barrier, the reflection and transmission coefficients (R, T) are obtained. At last, we also compare the coefficients with the usual 4D counterpart.

scholarly journals Quasi-normal modes and the area spectrum of a near extremal de Sitter black hole with conformally coupled scalar field

2015 ◽  
Vol 30 (11) ◽  
pp. 1550057 ◽  
Author(s):  
Sharmanthie Fernando
Keyword(s):  
Black Hole ◽  
Wave Equation ◽  
Scalar Field ◽  
Normal Modes ◽  
Type Equation ◽  
Area Spectrum ◽  
Massless Scalar ◽  
Massless Scalar Field ◽  
De Sitter ◽  
Quasi Normal Mode

In this paper, we have studied a black hole in de Sitter space which has a conformally coupled scalar field in the background. This black hole is also known as the MTZ black hole. We have obtained exact values for the quasi-normal mode (QNM) frequencies under massless scalar field perturbations. We have demonstrated that when the black hole is near-extremal, that the wave equation for the massless scalar field simplifies to a Schrödinger type equation with the well-known Pöschl–Teller potential. We have also used sixth-order WKB approximation to compute QNM frequencies to compare with exact values obtained via the Pöschl–Teller method for comparison. As an application, we have obtained the area spectrum using modified Hods approach and show that it is equally spaced.

scholarly journals EQUIVALENCE BETWEEN PALATINI AND METRIC FORMALISMS OF f(R)-GRAVITY BY DIVERGENCE-FREE CURRENT

2011 ◽  
Vol 26 (01) ◽  
pp. 65-72 ◽  
Author(s):  
SALVATORE CAPOZZIELLO ◽  
FARHAD DARABI ◽  
DANIELE VERNIERI
Keyword(s):  
Field Equation ◽  
Scalar Field ◽  
Conservation Equation ◽  
Auxiliary Field ◽  
General Context ◽  
Massless Scalar ◽  
Massless Scalar Field ◽  
Scalar Field Equation ◽  
Divergence Free ◽  
Free Current

The equivalence between metric and Palatini formalisms in f(R)-gravity can be achieved in the general context of theories with divergence-free current. This equivalence is a necessary result of a symmetry which is included in a particular conservation equation of the current. In fact the conservation equation, by an appropriate redefinition of the introduced auxiliary field, may be encoded in a massless scalar field equation.

THE SCALAR FIELD IN EXTREME REISSNER–NORDSTRÖM–DE SITTER SPACE

2003 ◽  
Vol 18 (26) ◽  
pp. 4829-4836 ◽  
Author(s):  
GUANG-HAI GUO ◽  
YUAN-XING GUI ◽  
JIAN-XIANG TIAN
Keyword(s):  
Black Hole ◽  
Field Equation ◽  
Scalar Field ◽  
Special Interest ◽  
Field Amplitude ◽  
Cosmological Horizon ◽  
De Sitter ◽  
Reflection And Transmission ◽  
Transmission Coefficients ◽  
Tortoise Coordinate

By generalizing the method of I. Brevik et al. the scalar field equation between the outer black hole horizon and the cosmological horizon in the extreme Reissner–Nordström–de Sitter (RNdS) geometry is solved. The field amplitude, as well as the potential, is shown graphically by introducing the "tangent" approximation, which is more exact than that used by I. Brevik et al., of the tortoise coordinate. There are two limiting cases of our special interest. The first one is when the cosmological horizon is very close to the outer horizon of the "black hole." The second one is when they are far apart. And the reflection and transmission coefficients are worked out in the two cases respectively.

scholarly journals A (gravitational) toy story

2017 ◽  
Vol 26 (09) ◽  
pp. 1750096
Author(s):  
W. Barreto ◽  
H. P. de Oliveira ◽  
B. Rodriguez-Mueller
Keyword(s):  
Black Hole ◽  
Scalar Field ◽  
Critical Exponent ◽  
Critical Behavior ◽  
Massless Scalar ◽  
Massless Scalar Field ◽  
De Sitter ◽  
Hole Formation ◽  
Black Hole Formation ◽  
Mass Gap

Frequently in Physics, insights and conclusions can be drawn from simple, idealized models. The discovery of critical behavior in the gravitational collapse of a massless scalar field leads to the simulation of binary black holes, from its coalescence to merging and ringdown. We refined a toy model to explore black hole formation as these events unfold to revisit the instability of a gravitational kink. We confirmed a conjecture related to a mass gap for critical behavior at the threshold of black hole formation. We find a critical exponent twice the standard value. Surprisingly, this larger critical exponent is also present in the multiple critical behavior for the black hole formation from a massless scalar field in asymptotically anti-de Sitter spacetimes. What is the meaning of this mass gap? Does it have physical relevance?

scholarly journals Regular black holes in de Sitter universe: Scalar field perturbations and quasinormal modes

2015 ◽  
Vol 24 (14) ◽  
pp. 1550104 ◽  
Author(s):  
Sharmanthie Fernando
Keyword(s):  
Black Hole ◽  
Scalar Field ◽  
Cosmological Constant ◽  
Quasinormal Modes ◽  
Massless Scalar ◽  
Massless Scalar Field ◽  
De Sitter ◽  
Regular Black Hole ◽  
Text Mode ◽  
De Sitter Universe

The purpose of this paper is to study quasinormal modes (QNMs) of a regular black hole with a cosmological constant due to scalar perturbations. A detailed study of QNMs frequencies for the massless scalar field was done by varying the parameters of the theory such as mass, magnetic charge, cosmological constant and the spherical harmonic index. We have employed the sixth-order WKB approximation to compute the QNMs frequencies. We have also proved analytically that the [Formula: see text] mode for the massless field reaches a constant value at late times. We have approximated the near-extreme regular-de Sitter (dS) black hole potential with the Pöschl–Teller potential to obtain exact frequencies. The null geodesics of the regular-de Sitter black hole is employed to describe the QNMs frequencies at the eikonal limit ([Formula: see text]).

Cylindrically symmetric unimodular f(R) black holes

2021 ◽  
pp. 2150101
Author(s):  
Hüseyi̇n Aydın ◽  
Meli̇s Ulu Dog̃ru
Keyword(s):  
Black Hole ◽  
Scalar Field ◽  
Equations Of Motion ◽  
Energy Conditions ◽  
Massless Scalar ◽  
Massless Scalar Field ◽  
De Sitter ◽  
Field Equations ◽  
Black Hole Spacetimes ◽  
Cylindrically Symmetric

In this paper, we examine massless scalar field by using unimodular [Formula: see text] theory. It is taken into account unimodular and cylindrically symmetric spacetime which provides convenience in researching black hole. The field equations in unimodular [Formula: see text] theory for given spacetime with massless scalar field and additional Bianchi identities are solved. Cylindrically symmetric anti-de Sitter (AdS)–Schwarzschild-like and AdS–Reissner–Nordström-like black hole spacetimes are achieved. Equations of motion are derived by using Hamiltonian. Orbits of massless test particles are depicted. Obtained line element asymptotically converges to dS/AdS spacetime. Weak and strong energy conditions of the massless scalar field are obtained with Raychaudhuri equations in unimodular [Formula: see text] theory. Also, stiff fluid interpretation of scalar field is reviewed.

scholarly journals RADIATION AND POTENTIAL BARRIERS OF A 5D BLACK STRING SOLUTION

2006 ◽  
Vol 21 (39) ◽  
pp. 2937-2945 ◽  
Author(s):  
MOLIN LIU ◽  
HONGYA LIU ◽  
LIXIN XU ◽  
PAUL S. WESSON
Keyword(s):  
Black Hole ◽  
Massless Scalar ◽  
Massless Scalar Field ◽  
De Sitter ◽  
Black String ◽  
String Solution ◽  
Brane Model ◽  
Black Hole Radiation ◽  
Fifth Dimension ◽  
Dimensional Spacetime

By using a massless scalar field we examine the effect of an extra dimension on black hole radiation. As the equations are coupled, we find that the structure of the fifth dimension (as for membrane and induced-matter theory) affects the nature of the radiation observed in four-dimensional spacetime. In the case of the Schwarzschild–de Sitter solution embedded in a Randall–Sundrum brane model, the extension of the black hole along the fifth dimension looks like a black string. Then it is shown that, on the brane, the potential barrier surrounding the black hole has a quantized as well as a continuous spectrum. In principle, Hawking radiation may thus provide a probe for higher dimensions.

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