scholarly journals ROTATING BLACK HOLES IN HIGHER DIMENSIONAL BRANE WORLDS

2006 ◽  
Vol 15 (02) ◽  
pp. 171-188 ◽  
Author(s):  
GAUTAM SENGUPTA
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Causal Structure ◽  
Brane World ◽  
Black String ◽  
Brane Worlds ◽  
Rotating Black Hole ◽  
Geodesic Equations ◽  
Higher Dimensional ◽  
Rotating Black Holes

A black string generalization of the Myers–Perry N-dimensional rotating black hole is considered in an (N + 1)-dimensional Randall–Sundrum brane world. The black string intercepts the (N - 1) brane in a N-dimensional rotating black hole. We examine the diverse cases arising for various non-zero rotation components and obtain the geodesic equations for these space–times. The causal structure and asymptotics of the resulting brane world geometries are analyzed.

scholarly journals ROTATING BRANE WORLD BLACK HOLES

2002 ◽  
Vol 17 (23) ◽  
pp. 1479-1487 ◽  
Author(s):  
MONINDER SINGH MODGIL ◽  
SUKANTA PANDA ◽  
GAUTAM SENGUPTA
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Brane World ◽  
Black String ◽  
Rotating Black Hole ◽  
Geodesic Equations

A five-dimensional rotating black string in a Randall–Sundrum brane world is considered. The black string intercepts the three-brane in a four-dimensional rotating black hole. The geodesic equations and the asymptotics in this background are discussed.

scholarly journals BLACK-HOLE BOMBS AT THE LHC

2012 ◽  
Vol 27 (07) ◽  
pp. 1250038 ◽  
Author(s):  
JONG-PHIL LEE
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Rotating Black Hole ◽  
Field Amplification ◽  
Higher Dimensional ◽  
Original Field

A particle scattered off by a rotating black hole can be amplified when the system is in the superradiant regime. If the system is surrounded by a mirror which reflects the particle back to the black hole the whole system forms a black-hole bomb, amplifying the original field exponentially. We show in this paper that higher-dimensional black holes can also form black-hole bombs at the LHC. For a pion the e-folding time for the field amplification is tc ~ 10-23–10-24 sec . If the lifetime of the black hole is long enough compared with tc, we can observe severely amplified fields.

scholarly journals DENOUEMENT OF A WORMHOLE–BRANE ENCOUNTER

2009 ◽  
Vol 18 (12) ◽  
pp. 1809-1819
Author(s):  
ENRICO RODRIGO
Keyword(s):  
Black Holes ◽  
Dark Matter ◽  
Brane World ◽  
Dark Matter Candidate ◽  
Brane Worlds ◽  
Higher Dimensional ◽  
The Creation ◽  
World Ethos ◽  
Baby Universe

Higher-dimensional black holes have long been considered within the context of brane worlds. Recently, it was shown that the brane-world ethos also permits the consideration of higher-dimensional wormholes. When such a wormhole, pre-existing in the bulk, impinges upon our universe, taken to be a positive-tension three-brane, it can induce the creation in our universe of a wormhole of ordinary dimensionality. The throat of this wormhole might fully constrict, pinch off, and thus birth a baby universe. Alternatively, the induced wormhole might persist. I show that persistence is more likely and note that the persistent wormhole manifests itself as a particle-like object whose interaction with cosmic matter is purely gravitational. I consider the viability of this object as a dark matter candidate.

NUMERICAL TREATMENT OF THIN ACCRETION DISK DYNAMICS AROUND ROTATING BLACK HOLES

2010 ◽  
Vol 19 (13) ◽  
pp. 2111-2133 ◽  
Author(s):  
DENIZ YILDIRAN ◽  
ORHAN DONMEZ
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Steady State ◽  
Accretion Disk ◽  
Outer Boundary ◽  
Adiabatic Index ◽  
Opening Angle ◽  
Computational Domain ◽  
Rotating Black Hole ◽  
Rotating Black Holes

In the present study, we perform the numerical simulation of a relativistic thin accretion disk around the nonrotating and rapidly rotating black holes using the general relativistic hydrodynamic code with Kerr in Kerr–Schild coordinate that describes the central rotating black hole. Since the high energy X-rays are produced close to the event horizon resulting the black hole–disk interaction, this interaction should be modeled in the relativistic region. We have set up two different initial conditions depending on the values of thermodynamical variables around the black hole. In the first setup, the computational domain is filled with constant parameters without injecting gas from the outer boundary. In the second, the computational domain is filled with the matter which is then injected from the outer boundary. The matter is assumed to be at rest far from the black hole. Both cases are modeled over a wide range of initial parameters such as the black hole angular momentum, adiabatic index, Mach number and asymptotic velocity of the fluid. It has been found that initial values and setups play an important role in determining the types of the shock cone and in designating the events on the accretion disk. The continuing injection from the outer boundary presents a tail shock to the steady state accretion disk. The opening angle of shock cone grows as long as the rotation parameter becomes larger. A more compressible fluid (bigger adiabatic index) also presents a bigger opening angle, a spherical shock around the rotating black hole, and less accumulated gas in the computational domain. While results from [J. A. Font, J. M. A. Ibanez and P. Papadopoulos, Mon. Not. R. Astron. Soc.305 (1999) 920] indicate that the tail shock is warped around for the rotating hole, our study shows that it is the case not only for the warped tail shock but also for the spherical and elliptical shocks around the rotating black hole. The warping around the rotating black hole in our case is much smaller than the one by [J. A. Font, J. M. A. Ibanez and P. Papadopoulos, Mon. Not. R. Astron. Soc.305 (1999) 920], due to the representation of results at the different coordinates. Contrary to the nonrotating black hole, the tail shock is slightly warped around the rotating black hole. The filled computational domain without any injection leads to an unstable accretion disk. However much of it reaches a steady state for a short period of time and presents quasi-periodic oscillation (QPO). Furthermore, the disk tends to loose mass during the whole dynamical evolution. The time-variability of these types of accretion flowing close to the black hole may clarify the light curves in Sgr A*.

scholarly journals Constraining the tidal charge of brane black holes using their shadows

2020 ◽  
Vol 80 (8) ◽  
Author(s):  
Juliano C. S. Neves
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Event Horizon ◽  
Upper Bound ◽  
Brane World ◽  
Nonlocal Effect ◽  
Rotating Black Hole

Abstract A constraint on the tidal charge generated within a brane world is shown. Using the shadow of a rotating black hole in a brane context in order to describe the M87* parameters recently announced by the Event Horizon Telescope Collaboration, the deviation from circularity of the reported shadow produces an upper bound on the bulk’s nonlocal effect, which is conceived of as a tidal charge in the four-dimensional brane induced by the five-dimensional bulk. Therefore, a deviation from circularity $$\lesssim 10\%$$≲10% leads to an upper bound on the tidal charge $$\lesssim 0.004M^2$$≲0.004M2.

scholarly journals Aschenbach effect for spinning particles in Kerr–(A)dS spacetime

2021 ◽  
Vol 81 (4) ◽  
Author(s):  
Ali Vahedi ◽  
Jafar Khodagholizadeh ◽  
Arman Tursunov
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Cosmological Constant ◽  
Test Particle ◽  
Critical Value ◽  
Frame Of Reference ◽  
Rotating Frame ◽  
Spinning Particles ◽  
Rotating Black Hole ◽  
Rotating Black Holes

AbstractA non-monotonic behavior of the velocity gradient of a test particle revolving around a rapidly rotating black hole in the locally non-rotating frame of reference is known as the Aschenbach effect. This effect can serve as a distinguishing signature of rapidly rotating black holes, being potentially useful for the measurements of the astrophysical black hole spins. This paper is the generalization of our previous research to the motion of spinning particles around a rotating black hole with non-zero cosmological constant. We show that both the particle’s spin s and the cosmological constant $$\Lambda $$ Λ modify the critical value of the black hole spin $$a_c$$ a c , for which the Aschenbach effect can be observed; $$a_c$$ a c can increase or decrease depending on the signs of s and $$\Lambda $$ Λ . We also found that the particle’s spin s can mimic the effect of the cosmological constant $$\Lambda $$ Λ for a given $$a_c$$ a c , causing thus a discrepancy in the measurements of s, $$\Lambda $$ Λ and $$a_c$$ a c in the Aschenbach effect.

scholarly journals Renormalized vacuum polarization of rotating black holes

2015 ◽  
Vol 24 (09) ◽  
pp. 1542007 ◽  
Author(s):  
Hugo R. C. Ferreira
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Vacuum Polarization ◽  
Kerr Black Hole ◽  
Quantum Field ◽  
Massive Scalar Field ◽  
Rotating Black Hole ◽  
Black Hole Spacetimes ◽  
Rotating Black Holes ◽  
General Method

Quantum field theory on rotating black hole spacetimes is plagued with technical difficulties. Here, we describe a general method to renormalize and compute the vacuum polarization of a quantum field in the Hartle–Hawking state on rotating black holes. We exemplify the technique with a massive scalar field on the warped AdS3 black hole solution to topologically massive gravity, a deformation of (2 + 1)-dimensional Einstein gravity. We use a "quasi-Euclidean" technique, which generalizes the Euclidean techniques used for static spacetimes, and we subtract the divergences by matching to a sum over mode solutions on Minkowski spacetime. This allows us, for the first time, to have a general method to compute the renormalized vacuum polarization, for a given quantum state, on a rotating black hole, such as the physically relevant case of the Kerr black hole in four dimensions.

scholarly journals Brane cosmology and the self-tuning of the cosmological constant in the presence of bulk black holes

2020 ◽  
Vol 80 (7) ◽  
Author(s):  
P. Betzios ◽  
O. Papadoulaki
Keyword(s):  
Black Hole ◽  
Cosmological Constant ◽  
Static Solution ◽  
Brane World ◽  
De Sitter ◽  
Brane Cosmology ◽  
Brane Worlds ◽  
Higher Dimensional ◽  
Self Tuning ◽  
Hole Geometry

Abstract Motivated by the holographic self-tuning proposal of the cosmological constant, we generalize and study the cosmology of brane-worlds embedded in a higher-dimensional bulk black hole geometry. We describe the equations and matching conditions in the case of flat, spherical and hyperbolic slicing of the bulk geometry and find the conditions for the existence of a static solution. We solve the equations that govern dynamical geometries in the probe brane limit and we describe in detail the resulting brane-world cosmologies. Of particular interest are the properties of solutions when the brane-world approaches the black hole horizon. In this case the geometry induced on the brane is that of de Sitter, whose entropy and temperature is related to those of the higher dimensional bulk black hole.

scholarly journals Black hole hair removal for N = 4 CHL models

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
Subhroneel Chakrabarti ◽  
Suresh Govindarajan ◽  
P. Shanmugapriya ◽  
Yogesh K. Srivastava ◽  
Amitabh Virmani
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Degrees Of Freedom ◽  
Microscopic Analysis ◽  
Flat Space ◽  
Special Care ◽  
Hair Removal ◽  
Partition Functions ◽  
Rotating Black Holes

Abstract Although BMPV black holes in flat space and in Taub-NUT space have identical near-horizon geometries, they have different indices from the microscopic analysis. For K3 compactification of type IIB theory, Sen et al. in a series of papers identified that the key to resolving this puzzle is the black hole hair modes: smooth, normalisable, bosonic and fermionic degrees of freedom living outside the horizon. In this paper, we extend their study to N = 4 CHL orbifold models. For these models, the puzzle is more challenging due to the presence of the twisted sectors. We identify hair modes in the untwisted as well as twisted sectors. We show that after removing the contributions of the hair modes from the microscopic partition functions, the 4d and 5d horizon partition functions agree. Special care is taken to present details on the smoothness analysis of hair modes for rotating black holes, thereby filling an essential gap in the literature.

scholarly journals Causality of black holes in 4-dimensional Einstein–Gauss–Bonnet–Maxwell theory

2020 ◽  
Vol 80 (8) ◽  
Author(s):  
Xian-Hui Ge ◽  
Sang-Jin Sin
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Shear Viscosity ◽  
Upper Bound ◽  
Causal Structure ◽  
Density Ratio ◽  
Entropy Density ◽  
Coupling Constant ◽  
Maxwell Theory ◽  
Black Hole Solutions

Abstract We study charged black hole solutions in 4-dimensional (4D) Einstein–Gauss–Bonnet–Maxwell theory to the linearized perturbation level. We first compute the shear viscosity to entropy density ratio. We then demonstrate how bulk causal structure analysis imposes an upper bound on the Gauss–Bonnet coupling constant in the AdS space. Causality constrains the value of Gauss–Bonnet coupling constant $$\alpha _{GB}$$αGB to be bounded by $$\alpha _{GB}\le 0$$αGB≤0 as $$D\rightarrow 4$$D→4.

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