scholarly journals Gravitational redshift/blueshift of light emitted by geodesic test particles, frame-dragging and pericentre-shift effects, in the Kerr–Newman–de Sitter and Kerr–Newman black hole geometries

2021 ◽  
Vol 81 (2) ◽  
Author(s):  
G. V. Kraniotis
Keyword(s):  
Black Hole ◽  
Killing Vector ◽  
Exact Formula ◽  
De Sitter ◽  
Null Geodesics ◽  
Distant Observer ◽  
Frame Dragging ◽  
Black Hole Spacetime ◽  
Analytic Expressions ◽  
Constants Of Motion

AbstractWe investigate the redshift and blueshift of light emitted by timelike geodesic particles in orbits around a Kerr–Newman–(anti) de Sitter (KN(a)dS) black hole. Specifically we compute the redshift and blueshift of photons that are emitted by geodesic massive particles and travel along null geodesics towards a distant observer-located at a finite distance from the KN(a)dS black hole. For this purpose we use the killing-vector formalism and the associated first integrals-constants of motion. We consider in detail stable timelike equatorial circular orbits of stars and express their corresponding redshift/blueshift in terms of the metric physical black hole parameters (angular momentum per unit mass, mass, electric charge and the cosmological constant) and the orbital radii of both the emitter star and the distant observer. These radii are linked through the constants of motion along the null geodesics followed by the photons since their emission until their detection and as a result we get closed form analytic expressions for the orbital radius of the observer in terms of the emitter radius, and the black hole parameters. In addition, we compute exact analytic expressions for the frame dragging of timelike spherical orbits in the KN(a)dS spacetime in terms of multivariable generalised hypergeometric functions of Lauricella and Appell. We apply our exact solutions of timelike non-spherical polar KN geodesics for the computation of frame-dragging, pericentre-shift, orbital period for the orbits of S2 and S14 stars within the $$1^{\prime \prime }$$ 1 ″ of SgrA*. We solve the conditions for timelike spherical orbits in KN(a)dS and KN spacetimes. We present new, elegant compact forms for the parameters of these orbits. Last but not least we derive a very elegant and novel exact formula for the periapsis advance for a test particle in a non-spherical polar orbit in KNdS black hole spacetime in terms of Jacobi’s elliptic function sn and Lauricella’s hypergeometric function $$F_D$$ F D .

scholarly journals Non-Singular Model of Magnetized Black Hole Based on Nonlinear Electrodynamics

Universe ◽  
2019 ◽  
Vol 5 (12) ◽  
pp. 225 ◽  
Author(s):  
Sergey I. Kruglov
Keyword(s):  
Black Holes ◽  
Heat Capacity ◽  
Black Hole ◽  
Hawking Temperature ◽  
Nonlinear Electrodynamics ◽  
De Sitter ◽  
Fundamental Length ◽  
Gravity Effects ◽  
Black Hole Spacetime ◽  
Thermodynamics Of Black Holes

A new modified Hayward metric of magnetically charged non-singular black hole spacetime in the framework of nonlinear electrodynamics is constructed. When the fundamental length introduced, characterising quantum gravity effects, vanishes, one comes to the general relativity coupled with the Bronnikov model of nonlinear electrodynamics. The metric can have one (an extreme) horizon, two horizons of black holes, or no horizons corresponding to the particle-like solution. Corrections to the Reissner–Nordström solution are found as the radius approaches infinity. As r → 0 the metric has a de Sitter core showing the absence of singularities, the asymptotic of the Ricci and Kretschmann scalars are obtained and they are finite everywhere. The thermodynamics of black holes, by calculating the Hawking temperature and the heat capacity, is studied. It is demonstrated that phase transitions take place when the Hawking temperature possesses the maximum. Black holes are thermodynamically stable at some range of parameters.

scholarly journals Thermal activation of thin-shells in anti-de Sitter black hole spacetime

2017 ◽  
Vol 2017 (7) ◽  
Author(s):  
Pisin Chen ◽  
Guillem Domènech ◽  
Misao Sasaki ◽  
Dong-han Yeom
Keyword(s):  
Black Hole ◽  
Thermal Activation ◽  
Thin Shells ◽  
De Sitter ◽  
Black Hole Spacetime

scholarly journals Light from Reissner–Nordstrom–de Sitter black holes

2021 ◽  
pp. 2150162
Author(s):  
Ion I. Cotăescu
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Expanding Universe ◽  
De Sitter ◽  
Principal Parameter ◽  
Null Geodesics ◽  
Charged Black Holes ◽  
Peculiar Velocities ◽  
First Time

We derive for the first time the form of the spiral null geodesics around the photon sphere of the Reissner–Nordstrom black hole in the de Sitter expanding universe. Moreover, we obtain the principal parameter we need for deriving, according to our method [I. I. Cotăescu, Eur. Phys. J. C 81, 32 (2021)], the black hole shadow and the related redshift as measured by a remote observer situated in the asymptotic zone. We obtain thus a criterion of detecting charged black holes without peculiar velocities when one knows the mass, redshift and the black hole shadow.

scholarly journals MOTION OF CHARGED PARTICLES ON THE REISSNER–NORDSTRÖM (ANTI)-DE SITTER BLACK HOLE SPACETIME

2011 ◽  
Vol 26 (39) ◽  
pp. 2923-2950 ◽  
Author(s):  
MARCO OLIVARES ◽  
JOEL SAAVEDRA ◽  
CARLOS LEIVA ◽  
JOSÉ R. VILLANUEVA
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Charged Particles ◽  
De Sitter ◽  
Point Particles ◽  
Charged Black Holes ◽  
Black Hole Spacetime ◽  
Jacobi Functions ◽  
Electrically Charged ◽  
Charged Point

We study the motion of relativistic, electrically charged point particles in the background of charged black holes with nontrivial asymptotic behavior. We compute the exact trajectories of massive particles and express them in terms of elliptic Jacobi functions. As a result, we obtain a detailed description of particles orbits in the gravitational field of Reissner–Nordström (anti)-de Sitter black hole, depending of their charge, mass and energy.

scholarly journals Optical and thermodynamic properties of a rotating dyonic black hole spacetime in $${\mathcal {N}} = 2, U(1)^2$$ gauged supergravity

2021 ◽  
Vol 81 (5) ◽  
Author(s):  
Prateek Sharma ◽  
Hemwati Nandan ◽  
Uma Papnoi ◽  
Arindam Kumar Chatterjee
Keyword(s):  
Heat Capacity ◽  
Black Hole ◽  
Thermodynamic Properties ◽  
Thermodynamic Parameters ◽  
Thermodynamic Stability ◽  
Null Geodesics ◽  
Black Hole Spacetime

AbstractThe null geodesics and the distance of closest approach for photon around a rotating dyonic black hole in $${\mathcal {N}} = 2, U(1)^2$$ N = 2 , U ( 1 ) 2 gauged supergravity is studied. The phenomenon of black hole shadows with various black hole parameters has also analyzed. Further, the investigation of various thermodynamic properties for this black hole is performed with various thermodynamic parameters at the horizon. The heat capacity to study the thermodynamic stability of this black hole spacetime is also studied. The influence for different values of the black hole parameters $$ \nu $$ ν , e, $$ \nu $$ ν , g and $$N_{g}$$ N g on the phenomenon of black hole shadows and thermodynamic parameters is also investigated visually.

scholarly journals Regular black hole interior spacetime supported by three-form field

2021 ◽  
Vol 81 (4) ◽  
Author(s):  
Mariam Bouhmadi-López ◽  
Che-Yu Chen ◽  
Xiao Yan Chew ◽  
Yen Chin Ong ◽  
Dong-han Yeom
Keyword(s):  
Black Hole ◽  
Energy Condition ◽  
Null Energy Condition ◽  
De Sitter ◽  
Regular Black Hole ◽  
Black Hole Spacetime ◽  
Form Field ◽  
Black Hole Interior ◽  
Metric Function ◽  
Geodesically Complete

AbstractIn this paper, we show that a minimally coupled 3-form endowed with a proper potential can support a regular black hole interior. By choosing an appropriate form for the metric function representing the radius of the 2-sphere, we solve for the 3-form field and its potential. Using the obtained solution, we construct an interior black hole spacetime which is everywhere regular. The singularity is replaced with a Nariai-type spacetime, whose topology is $$\text {dS}_2 \times \text {S}^2$$ dS 2 × S 2 , in which the radius of the 2-sphere is constant. So long as the interior continues to expand indefinitely, the geometry becomes essentially compactified. The 2-dimensional de Sitter geometry appears despite the negative potential of the 3-form field. Such a dynamical compactification could shed some light on the origin of de Sitter geometry of our Universe, exacerbated by the Swampland conjecture. In addition, we show that the spacetime is geodesically complete. The geometry is singularity-free due to the violation of the null energy condition.

scholarly journals REAL TUNNELING AND BLACK HOLE CREATION

1998 ◽  
Vol 07 (01) ◽  
pp. 111-127 ◽  
Author(s):  
ZHONG CHAO WU
Keyword(s):  
Black Hole ◽  
De Sitter ◽  
Planck Constant ◽  
Gravitational Instanton ◽  
Constrained Gravitational Instanton ◽  
Black Hole Spacetime ◽  
Sitter Background ◽  
Transition Surface ◽  
The Universe ◽  
Black Hole Creation

We discuss the Hawking theory of quantum cosmology with regard to approximation at the lowest order of the Planck constant. At this level, the quantum scenario will be reduced to its classical evolutions in real and imaginary times. We restrict our attention to the so-called real tunneling case. It can be shown that, even at this level, there still exist some quantum effects, the classical field equation may not hold at the transition surface. One can introduce the concept of constrained gravitational instanton. It may play some important role in the scenario of black hole creation in the inflationary background at the Planckian era of the universe. From the constrained gravitational instanton, the real tunneling can occur through different ways. Consequently, it will lead to the creation of different parts of the black hole spacetime in the de Sitter background. The global aspects of the black hole creation are discussed.

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