scholarly journals Constraining LQG Graph with Light Surfaces: Properties of BH Thermodynamics for Mini-Super-Space, Semi-Classical Polymeric BH

Entropy ◽  
2020 ◽  
Vol 22 (4) ◽  
pp. 402
Author(s):  
Daniela Pugliese ◽  
Giovanni Montani
Keyword(s):  
Black Hole ◽  
Loop Quantum Gravity ◽  
Causal Structure ◽  
Thermodynamic Characteristics ◽  
Kerr Geometry ◽  
Regular Black Hole ◽  
Loop Area ◽  
Symmetric Spacetimes ◽  
Wide Range ◽  
Limiting Case

This work participates in the research for potential areas of observational evidence of quantum effects on geometry in a black hole astrophysical context. We consider properties of a family of loop quantum corrected regular black hole (BHs) solutions and their horizons, focusing on the geometry symmetries. We study here a recently developed model, where the geometry is determined by a metric quantum modification outside the horizon. This is a regular static spherical solution of mini-super-space BH metric with Loop Quantum Gravity (LQG) corrections. The solutions are characterized delineating certain polymeric functions on the basis of the properties of the horizons and the emergence of a singularity in the limiting case of the Schwarzschild geometry. We discuss particular metric solutions on the base of the parameters of the polymeric model related to similar properties of structures, the metric Killing bundles (or metric bundles MBs), related to the BH horizons’ properties. A comparison with the Reissner–Norström geometry and the Kerr geometry with which analogies exist from the point of their respective MBs properties is done. The analysis provides a way to recognize these geometries and detect their main distinctive phenomenological evidence of LQG origin on the basis of the detection of stationary/static observers and the properties of light-like orbits within the analysis of the (conformal invariant) MBs related to the (local) causal structure. This approach could be applied in other quantum corrected BH solutions, constraining the characteristics of the underlining LQG-graph, as the minimal loop area, through the analysis of the null-like orbits and photons detection. The study of light surfaces associated with a diversified and wide range of BH phenomenology and grounding MBs definition provides a channel to search for possible astrophysical evidence. The main BHs thermodynamic characteristics are studied as luminosity, surface gravity, and temperature. Ultimately, the application of this method to this spherically symmetric approximate solution provides us with a way to clarify some formal aspects of MBs, in the presence of static, spherical symmetric spacetimes.

scholarly journals Testing Kerr black hole mimickers with quasi-periodic oscillations from GRO J1655-40

2021 ◽  
Vol 81 (11) ◽  
Author(s):  
Xin Jiang ◽  
Peng Wang ◽  
Haitang Yang ◽  
Houwen Wu
Keyword(s):  
Black Hole ◽  
Kerr Black Hole ◽  
Compact Object ◽  
Kerr Metric ◽  
Observation Data ◽  
Periodic Oscillations ◽  
Regular Black Hole ◽  
Rotating Black Hole ◽  
Traversable Wormholes ◽  
Limiting Case

AbstractThe measurements of quasi-periodic oscillations (QPOs) provide a quite powerful tool to test the nature of astrophysical black hole candidates in the strong gravitational field regime. In this paper, we use QPOs within the relativistic precession model to test a recently proposed family of rotating black hole mimickers, which reduce to the Kerr metric in a limiting case, and can represent traversable wormholes or regular black holes with one or two horizons, depending on the values of the parameters. In particular, assuming that the compact object of GRO J1655-40 is described by a rotating black hole mimicker, we perform a $$\chi $$ χ -square analysis to fit the parameters of the mimicker with two sets of observed QPO frequencies from GRO J1655-40. Our results indicate that although the metric around the compact object of GRO J1655-40 is consistent with the Kerr metric, a regular black hole with one horizon is favored by the observation data of GRO J1655-40.

scholarly journals Gravitational and Electromagnetic Perturbations of a Charged Black Hole in a General Gauge Condition

Particles ◽  
2021 ◽  
Vol 4 (2) ◽  
pp. 106-128
Author(s):  
Claudia Moreno ◽  
Juan Carlos Degollado ◽  
Darío Núñez ◽  
Carlos Rodríguez-Leal
Keyword(s):  
Black Hole ◽  
Scalar Function ◽  
Gauge Condition ◽  
Fluid Distribution ◽  
Electromagnetic Signal ◽  
Charged Fluid ◽  
Coupled Equations ◽  
Electromagnetic Signals ◽  
Limiting Case ◽  
Weyl Scalar

We derive a set of coupled equations for the gravitational and electromagnetic perturbation in the Reissner–Nordström geometry using the Newman–Penrose formalism. We show that the information of the physical gravitational signal is contained in the Weyl scalar function Ψ4, as is well known, but for the electromagnetic signal, the information is encoded in the function χ, which relates the perturbations of the radiative Maxwell scalars φ2 and the Weyl scalar Ψ3. In deriving the perturbation equations, we do not impose any gauge condition and as a limiting case, our analysis contains previously obtained results, for instance, those from Chandrashekhar’s book. In our analysis, we also include the sources for the perturbations and focus on a dust-like charged fluid distribution falling radially into the black hole. Finally, by writing the functions on the basis of spin-weighted spherical harmonics and the Reissner–Nordström spacetime in Kerr–Schild type coordinates, a hyperbolic system of coupled partial differential equations is presented and numerically solved. In this way, we completely solve a system that generates a gravitational signal as well as an electromagnetic/gravitational one, which sets the basis to find correlations between them and thus facilitates gravitational wave detection via electromagnetic signals.

scholarly journals Quantum gravity: A brief history of ideas and some prospects

2015 ◽  
Vol 24 (11) ◽  
pp. 1530028 ◽  
Author(s):  
Steven Carlip ◽  
Dah-Wei Chiou ◽  
Wei-Tou Ni ◽  
Richard Woodard
Keyword(s):  
Black Hole ◽  
String Theory ◽  
Quantum Gravity ◽  
Loop Quantum Gravity ◽  
Black Hole Thermodynamics ◽  
History Of Ideas ◽  
Foreseeable Future ◽  
Gravitational Effects ◽  
History Of

We present a bird's-eye survey on the development of fundamental ideas of quantum gravity, placing emphasis on perturbative approaches, string theory, loop quantum gravity (LQG) and black hole thermodynamics. The early ideas at the dawn of quantum gravity as well as the possible observations of quantum gravitational effects in the foreseeable future are also briefly discussed.

scholarly journals Regular black hole motion and stellar orbital resonances

2007 ◽  
Vol 383 (4) ◽  
pp. 1619-1638 ◽  
Author(s):  
C. M. Boily ◽  
T. Padmanabhan ◽  
A. Paiement
Keyword(s):  
Black Hole ◽  
Regular Black Hole ◽  
Orbital Resonances

scholarly journals Black Hole Interior from Loop Quantum Gravity

2008 ◽  
Vol 2008 ◽  
pp. 1-12 ◽  
Author(s):  
Leonardo Modesto
Keyword(s):  
Black Hole ◽  
Quantum Gravity ◽  
Event Horizon ◽  
Loop Quantum Gravity ◽  
Planck Scale ◽  
Semiclassical Analysis ◽  
Schwarzschild Solution ◽  
Quantum Black Hole ◽  
Minimum Value ◽  
Black Hole Interior

We calculate modifications to the Schwarzschild solution by using a semiclassical analysis of loop quantum black hole. We obtain a metric inside the event horizon that coincides with the Schwarzschild solution near the horizon but that is substantially different at the Planck scale. In particular, we obtain a bounce of theS2sphere for a minimum value of the radius and that it is possible to have another event horizon close to ther=0point.

On embeddings of the Kerr geometry

1981 ◽  
Vol 59 (5) ◽  
pp. 688-692 ◽  
Author(s):  
Nigel A. Sharp
Keyword(s):  
Black Hole ◽  
Event Horizon ◽  
Equatorial Plane ◽  
Kerr Metric ◽  
Intrinsic Structure ◽  
Kerr Geometry ◽  
Rotating Black Hole ◽  
Isometric Embeddings

The use of isometric embeddings of curved geometries reveals their intrinsic structure in a way that is readily appreciated. This is done for 3 two-surfaces sliced from the Kerr metric which describes a rotating black hole: the equatorial plane, the event horizon, and the ergosurface.

scholarly journals ENTROPY AND AREA IN LOOP QUANTUM GRAVITY

2005 ◽  
Vol 14 (12) ◽  
pp. 2301-2305
Author(s):  
JOHN SWAIN
Keyword(s):  
Black Hole ◽  
Quantum Gravity ◽  
Maximum Entropy ◽  
Degrees Of Freedom ◽  
Loop Quantum Gravity ◽  
Black Hole Entropy ◽  
Black Hole Thermodynamics ◽  
Three Dimensions ◽  
Spin Network

Black hole thermodynamics suggests that the maximum entropy that can be contained in a region of space is proportional to the area enclosing it rather than its volume. We argue that this follows naturally from loop quantum gravity and a result of Kolmogorov and Bardzin' on the the realizability of networks in three dimensions. This represents an alternative to other approaches in which some sort of correlation between field configurations helps limit the degrees of freedom within a region. It also provides an approach to thinking about black hole entropy in terms of states inside rather than on its surface. Intuitively, a spin network complicated enough to imbue a region with volume only lets that volume grow as quickly as the area bounding it.

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