scholarly journals Quantum-Only Metrics in Spherically Symmetric Gravity

2020 ◽  
Vol 2 (2) ◽  
pp. 314-325
Author(s):  
Giovanni Modanese
Keyword(s):  
Classical Limit ◽  
Transition Probability ◽  
Flat Space ◽  
Conformal Factor ◽  
Spherically Symmetric ◽  
Vacuum Fluctuations ◽  
Classical Analogue ◽  
Effective Dimensionality ◽  
The Continuum ◽  
Very Low Temperature

The Einstein action for the gravitational field has some properties which make of it, after quantization, a rare prototype of systems with quantum configurations that do not have a classical analogue. Assuming spherical symmetry in order to reduce the effective dimensionality, we have performed a Monte Carlo simulation of the path integral with transition probability e − β | S | . Although this choice does not allow to reproduce the full dynamics, it does lead us to find a large ensemble of metric configurations having action | S | ≪ ħ by several magnitude orders. These vacuum fluctuations are strong deformations of the flat space metric (for which S = 0 exactly). They exhibit a periodic polarization in the scalar curvature R. In the simulation we fix a length scale L and divide it into N sub-intervals. The continuum limit is investigated by increasing N up to ∼ 10 6 ; the average squared action ⟨ S 2 ⟩ is found to scale as 1 / N 2 and thermalization of the algorithm occurs at a very low temperature (classical limit). This is in qualitative agreement with analytical results previously obtained for theories with stabilized conformal factor in the asymptotic safety scenario.

scholarly journals Field of a charged particle in the presence of scalar meson fields in general relativity

1983 ◽  
Vol 24 (4) ◽  
pp. 461-465 ◽  
Author(s):  
D. R. K. Reddy ◽  
V. U. M. Rao
Keyword(s):  
Charged Particle ◽  
Point Charge ◽  
Scalar Meson ◽  
Scalar Fields ◽  
Flat Space ◽  
Spherically Symmetric ◽  
Conformally Flat ◽  
Field Equations ◽  
Conformally Flat Metric ◽  
Scalar Meson Field

AbstractField equations for coupled gravitational and zero mass scalar fields in the presence of a point charge are obtained with the aid of a static spherically symmetric conformally flat metric. A closed from exact solution of the field equations is presented which may be considered as describing the field of a charged particle at the origin surrounded by the scalar meson field in a flat space-time.

scholarly journals Spinning black holes with a separable Hamilton–Jacobi equation from a modified Newman–Janis algorithm

2020 ◽  
Vol 80 (11) ◽  
Author(s):  
Haroldo C. D. Lima Junior ◽  
Luís C. B. Crispino ◽  
Pedro V. P. Cunha ◽  
Carlos A. R. Herdeiro
Keyword(s):  
Black Holes ◽  
Jacobi Equation ◽  
Plasma Frequency ◽  
Conformal Factor ◽  
Matter Content ◽  
Spherically Symmetric ◽  
Einstein Field Equations ◽  
Field Equations ◽  
Original Procedure ◽  
Hamilton Jacobi Equation

AbstractObtaining solutions of the Einstein field equations describing spinning compact bodies is typically challenging. The Newman–Janis algorithm provides a procedure to obtain rotating spacetimes from a static, spherically symmetric, seed metric. It is not guaranteed, however, that the resulting rotating spacetime solves the same field equations as the seed. Moreover, the former may not be circular, and thus expressible in Boyer–Lindquist-like coordinates. Amongst the variations of the original procedure, a modified Newman–Janis algorithm (MNJA) has been proposed that, by construction, originates a circular, spinning spacetime, expressible in Boyer–Lindquist-like coordinates. As a down side, the procedure introduces an ambiguity, that requires extra assumptions on the matter content of the model. In this paper we observe that the rotating spacetimes obtained through the MNJA always admit separability of the Hamilton–Jacobi equation for the case of null geodesics, in which case, moreover, the aforementioned ambiguity has no impact, since it amounts to an overall metric conformal factor. We also show that the Hamilton–Jacobi equation for light rays propagating in a plasma admits separability if the plasma frequency obeys a certain constraint. As an illustration, we compute the shadow and lensing of some spinning black holes obtained by the MNJA.

scholarly journals Global Embeddings of BTZ and Schwarzschild-ADS Type Black Holes in a Flat Space

Symmetry ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 841 ◽  
Author(s):  
Anton Sheykin ◽  
Dmitry Solovyev ◽  
Sergey Paston
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Cosmological Constant ◽  
Isometric Embedding ◽  
Flat Space ◽  
Ambient Space ◽  
Spherically Symmetric ◽  
Btz Black Hole ◽  
3 Dimensional ◽  
Negative Cosmological Constant

We study the problem of construction of global isometric embedding for spherically symmetric black holes with negative cosmological constant in various dimensions. Firstly, we show that there is no such embedding for 4D RN-AdS black hole in 6D flat ambient space, completing the classification which we started earlier. Then we construct an explicit embedding of non-spinning BTZ black hole in 6D flat ambient space. Using this embedding as an anzats, we then construct a global explicit embedding of d-dimensional Schwarzschild-AdS black hole in a flat ( d + 3 ) -dimensional ambient space.

scholarly journals Comparison of Blanketing in a 3000 K, Oxygen Rich, Spherically Symmetric Model with the Blanketing in Non-Mira, M Giant Stars

1989 ◽  
Vol 106 ◽  
pp. 157-157
Author(s):  
G.C. Augason ◽  
J.A. Brown ◽  
D.R. Alexander
Keyword(s):  
Water Vapor ◽  
Model Parameters ◽  
Symmetric Model ◽  
Spherically Symmetric ◽  
Giant Stars ◽  
Symmetrical Model ◽  
Equilibrium Data ◽  
Spherically Symmetric Model ◽  
The Continuum ◽  
Flux Curve

A flux curve has been computed using a preliminary, spherically symmetric model for a 3000 K, oxygen rich, giant star. The model was computed using the opacity sampling method with an improved frequency set, improved molecular equilibrium data and an improved set of opacities. In addition, a continuum flux curve is computed using the same model and only continuum opacity sources. The relative and to some extent the absolute blanketing used to compute both the model and the flux curve derived from the model may be illustrated by dividing the normal flux curve by the continuum flux curve. This same procedure is used to illustrate the blanketing in an observed star by dividing the observed flux curve by the continuum flux curve. When this is done, the blanketing in an observed flux curve may be compared with the blanketing in a model. When this comparison is made, it is obvious that the treatment of blanketing in the “new” flux curve, computed using the spherically symmetric model and using new parameters, is superior to the flux curves based on earlier models. This is especially true in the regions of the fundamental, the first overtone and the second overtone of Co. Also, the new water vapor opacity is much improved. The new water vapor opacity is based on actual measurements of high temperature water vapor. Correct representation of water vapor opacity is extremely important for oxygen rich stars because it forms a psuedo continuum because of its many lines. The TiO opacity does not fit the observations well. When the spherically symmetrical model flux curve is compared directly to an observed flux curve, the new flux curve gives a better fit than do flux curves computed from previous models. There is still (at least for the non-Mira stars) a serious flux excess in the model flux curves at 1.6 microns in the region of the H minus b-f and f-f crossover. However, this excess is not as great for the spherically symmetric model as it is for earlier plane parallel models. It is not determined if this improvement is due to spherical symmetry or due to the new model parameters.

BLACK HOLES AND SOLITONS OF THE NONLINEAR ISOVECTOR MODEL

2006 ◽  
Vol 21 (21) ◽  
pp. 4343-4354 ◽  
Author(s):  
NEMATOLLAH RIAZI ◽  
HASSAN NIAD ◽  
SEYED HOSSEIN HENDI
Keyword(s):  
Strong Coupling ◽  
Asymptotic Form ◽  
Flat Space ◽  
Strong Coupling Regime ◽  
Spherically Symmetric ◽  
Coupling Constant ◽  
Curved Space ◽  
Dimensionless Coupling ◽  
Dimensionless Coupling Constant ◽  
Black Hole Solutions

We formulate the nonlinear isovector model in a curved background and calculate the spherically symmetric solutions for weak and strong coupling regimes. The question whether gravity has appreciable effects on the structure of solitons will be examined, in the framework of the calculated solutions, by comparing the flat-space and curved-space solutions. It turns out that in the strong coupling regime, gravity has essential effects on the solutions. It is also shown that the asymptotic form of the metric conforms with that of the charged Reissner–Nordstrom metric. The dimensionless coupling constant of the model has a limit, beyond which a horizon appears in the solutions, indicating the presence of black hole solutions.

scholarly journals Semi-classical BMS-blocks from the oscillator construction

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Martin Ammon ◽  
Seán Gray ◽  
Claire Moran ◽  
Michel Pannier ◽  
Katharina Wölfl
Keyword(s):  
Classical Limit ◽  
Flat Space ◽  
Highest Weight ◽  
Highest Weight Representation

Abstract Flat-space holography requires a thorough understanding of BMS symmetry. We introduce an oscillator construction of the highest-weight representation of the $$ {\mathfrak{bms}}_3 $$ bms 3 algebra and show that it is consistent with known results concerning the $$ {\mathfrak{bms}}_3 $$ bms 3 module. We take advantage of this framework to prove that $$ {\mathfrak{bms}}_3 $$ bms 3 -blocks exponentiate in the semi-classical limit, where one of the central charges is large. Within this context, we compute perturbatively heavy, and heavy-light vacuum $$ {\mathfrak{bms}}_3 $$ bms 3 -blocks.

scholarly journals Decay of bound states in the continuum of Majorana fermions induced by vacuum fluctuations: Proposal of qubit technology

2016 ◽  
Vol 93 (16) ◽  
Author(s):  
L. S. Ricco ◽  
Y. Marques ◽  
F. A. Dessotti ◽  
R. S. Machado ◽  
M. de Souza ◽  
...  
Keyword(s):  
Bound States ◽  
Majorana Fermions ◽  
Vacuum Fluctuations ◽  
The Continuum
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