Hawking effect of some axially symmetric non-stationary black holes

1994 ◽  
Vol 109 (5) ◽  
pp. 483-491 ◽  
Author(s):  
Zhao Zheng ◽  
Luo Zhi-qiang ◽  
Dai Xian-xin
Keyword(s):  
Black Holes ◽  
Axially Symmetric ◽  
Hawking Effect

scholarly journals A conserved energy for axially symmetric Newman–Penrose–Maxwell scalars on Kerr black holes

2019 ◽  
Vol 475 (2221) ◽  
pp. 20180686
Author(s):  
Nishanth Gudapati
Keyword(s):  
Black Holes ◽  
Poisson Bracket ◽  
Positive Definite ◽  
Parameter Family ◽  
Axially Symmetric ◽  
Energy Functionals ◽  
Kerr Black Holes ◽  
Maximal Space

We show that there exists a 1-parameter family of positive-definite and conserved energy functionals for axially symmetric Newman–Penrose–Maxwell scalars on the maximal space-like hypersurfaces in the exterior of Kerr black holes. It is also shown that the Poisson bracket within this 1-parameter family of energies vanishes on the maximal hypersurfaces.

scholarly journals Amplifying the Hawking Signal in BECs

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Roberto Balbinot ◽  
Alessandro Fabbri
Keyword(s):  
Black Holes ◽  
Casimir Effect ◽  
Pair Creation ◽  
Time Dependent ◽  
Dynamical Casimir Effect ◽  
Hawking Effect ◽  
Acoustic Black Holes ◽  
Bose Einstein ◽  
Simple Models

We consider simple models of Bose-Einstein condensates to study analog pair-creation effects, namely, the Hawking effect from acoustic black holes and the dynamical Casimir effect in rapidly time-dependent backgrounds. We also focus on a proposal by Cornell to amplify the Hawking signal in density-density correlators by reducing the atoms’ interactions shortly before measurements are made.

NONCOMMUTATIVE D-BRANE WORLD, BLACK HOLES AND EXTRA DIMENSIONS

2009 ◽  
Vol 24 (18n19) ◽  
pp. 3571-3576 ◽  
Author(s):  
SUPRIYA KAR
Keyword(s):  
Black Holes ◽  
String Theory ◽  
Extra Dimensions ◽  
Space Time ◽  
Brane World ◽  
Spherically Symmetric ◽  
Axially Symmetric ◽  
Ordinary Space ◽  
Classical Black Holes ◽  
Type Iib String Theory

Inspired by the space-time noncommutativity on a D5-brane world, in a type IIB string theory, we explore the possibility of an emergent 4D ordinary space-time in the formalism. In particular, a curved D3-brane dynamics is worked out to obtain an axially symmetric and a spherically symmetric AdS and dS black holes. Extremal geometries are analyzed, using the noncommutative scaling. The emerging two dimensional semi-classical black holes are investigated to yield evidence for extra dimensions in the curved brane-world. Interestingly, a tunneling between dS to AdS vacua in the formalism is briefly discussed by incorporating the Hagedorn transitions in string theory.

scholarly journals Dynamics of Electromagnetic Fields and Structure of Regular Rotating Electrically Charged Black Holes and Solitons in Nonlinear Electrodynamics Minimally Coupled to Gravity

Universe ◽  
2019 ◽  
Vol 5 (10) ◽  
pp. 205 ◽  
Author(s):  
Irina Dymnikova ◽  
Evgeny Galaktionov
Keyword(s):  
Black Holes ◽  
Electromagnetic Fields ◽  
Nonlinear Electrodynamics ◽  
Axially Symmetric ◽  
De Sitter ◽  
Dynamical Equations ◽  
Naked Singularities ◽  
Charged Black Holes ◽  
De Sitter Vacuum ◽  
Electrically Charged

We study the dynamics of electromagnetic fields of regular rotating electrically charged black holes and solitons replacing naked singularities in nonlinear electrodynamics minimally coupled to gravity (NED-GR). They are related by electromagnetic and gravitational interactions and described by the axially symmetric NED-GR solutions asymptotically Kerr-Newman for a distant observer. Geometry is described by the metrics of the Kerr-Schild class specified by T t t = T r r ( p r = − ρ ) in the co-rotating frame. All regular axially symmetric solutions obtained from spherical solutions with the Newman-Janis algorithm belong to this class. The basic generic feature of all regular objects of this class, both electrically charged and electrically neutral, is the existence of two kinds of de Sitter vacuum interiors. We analyze the regular solutions to dynamical equations for electromagnetic fields and show which kind of a regular interior is favored by electromagnetic dynamics for NED-GR objects.

scholarly journals Dependence of acoustic surface gravity on geometric configuration of matter for axially symmetric background flows in the Schwarzschild metric

2015 ◽  
Vol 24 (14) ◽  
pp. 1550096 ◽  
Author(s):  
Pratik Tarafdar ◽  
Tapas K. Das
Keyword(s):  
Black Holes ◽  
Fluid Flow ◽  
Boundary Conditions ◽  
Equations Of State ◽  
Initial Boundary ◽  
Stationary Flow ◽  
Geometric Configuration ◽  
Surface Gravity ◽  
Axially Symmetric ◽  
Schwarzschild Metric

In black hole evaporation process, the mass of the hole anti-correlates with the Hawking temperature. This indicates that the smaller holes have higher surface gravity. For analogue Hawking effects, however, the acoustic surface gravity is determined by the local values of the dynamical velocity of the stationary background fluid flow and the speed of propagation of the characteristic perturbation embedded in the background fluid, as well as by their space derivatives evaluated along the direction normal to the acoustic horizon, respectively. The mass of the analogue system — whether classical or quantum — does not directly contribute to extremize the value of the associated acoustic surface gravity. For general relativistic axially symmetric background fluid flow in the Schwarzschild metric, we show that the initial boundary conditions describing such accretion influence the maximization scheme of the acoustic surface gravity and associated analogue temperature. Aforementioned background flow onto black holes can assume three distinct geometric configurations. Identical set of initial boundary conditions can lead to entirely different phase-space behavior of the stationary flow solutions, as well as the salient features of the associated relativistic acoustic geometry. This implies that it is imperative to investigate how the measure of the acoustic surface gravity corresponding to the accreting black holes gets influenced by the geometric configuration of the inflow described by various thermodynamic equations of state. Such investigation is useful to study the effect of Einstenian gravity on the nonconventional classical features as observed in Hawking like effect in a dispersive medium in the limit of a strong dispersion relation.

Thermodynamics from field equations for charged radiating rotating black hole near horizon

2020 ◽  
Vol 35 (19) ◽  
pp. 2050092
Author(s):  
Uma Papnoi ◽  
Sushant G. Ghosh
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Field Equation ◽  
Thermodynamic Parameters ◽  
Apparent Horizon ◽  
Einstein Field Equation ◽  
Axially Symmetric ◽  
Field Equations ◽  
Rotating Black Hole

It is well known that near horizon black hole space–times show a resemblance to thermodynamic systems, it is easy to associate the thermodynamic parameters like temperature and entropy with them. In this paper, we study the connection between gravitational dynamics of the horizon and thermodynamics for the case of charged radiating rotating axially symmetric black holes. It is shown that Einstein field equation near apparent horizon can be interpreted in the form of thermodynamic law, i.e. [Formula: see text].

scholarly journals Gravitating Disks Around Black Holes

2009 ◽  
Vol 5 (S267) ◽  
pp. 332-332
Author(s):  
Vladimír Karas ◽  
Ladislav Šubr
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Gravitational Field ◽  
Relativistic Effects ◽  
Einstein Equations ◽  
Axially Symmetric ◽  
Disk System ◽  
Massive Black Hole ◽  
Black Hole Binary

AbstractFluid disks and tori around black holes are discussed within different approaches and with the emphasis on the role of disk gravity. We first review the prospects for investigating the gravitational field of a black hole–disk system by analytical solutions of stationary, axially symmetric Einstein equations. More detailed considerations are focused on the middle and outer parts of extended disk-like configurations where relativistic effects are small and the Newtonian description is adequate. As an example, we investigate the case of a torus near a massive black hole that is a member of the black-hole binary system.

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