Charged cylindrical collapse in f(𝒢) gravity

The aim of this paper is to study the gravitational collapse of charged cylindrical star in [Formula: see text] gravity. For this purpose, we derive dynamical equations by applying Misner–Sharp formalism and examine the effects of effective pressure and charge on the collapse rate. We also construct a relationship between matter variables, Gauss–Bonnet (GB) terms, and the Weyl tensor. For the constant value of [Formula: see text], it is found that spacetime is conformally flat if and only if the energy density is homogeneous. We conclude that the rate of collapse slows down in [Formula: see text] gravity due to anti-gravitational effects.

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Dynamics of perfect fluid collapse in f(𝒢,T) gravity

International Journal of Modern Physics D ◽

10.1142/s0218271819500548 ◽

2019 ◽

Vol 28 (03) ◽

pp. 1950054 ◽

Cited By ~ 3

Author(s):

M. Sharif ◽

M. Zeeshan Gul

Keyword(s):

Energy Density ◽

Perfect Fluid ◽

Junction Conditions ◽

Conformally Flat ◽

Dynamical Equations ◽

Spherical Collapse ◽

Exterior Regions ◽

Correction Terms ◽

Weyl Scalar ◽

Collapse Rate

This paper investigates the dynamics of perfect fluid spherical collapse in curvature-matter coupled gravity. Using Darmois junction conditions, we derive smooth matching of both interior and exterior regions. The dynamical equations are formulated through Misner–Sharp formalism that give the collapse rate for both general and constant curvature terms. Finally, we formulate a relationship between correction terms, Weyl scalar and matter variables. For constant value of [Formula: see text], it is found that the metric is conformally flat if and only if energy density of the collapsing system is homogeneous while the positive correction terms decrease the collapse rate.

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Dynamical Analysis of Charged Dissipative Cylindrical Collapse in Energy-Momentum Squared Gravity

Universe ◽

10.3390/universe7050154 ◽

2021 ◽

Vol 7 (5) ◽

pp. 154

Author(s):

Muhammad Zeeshan Gul ◽

Muhammad Sharif

Keyword(s):

General Relativity ◽

Electromagnetic Field ◽

Energy Density ◽

Weyl Tensor ◽

Dynamical Analysis ◽

Conformal Flatness ◽

The Impact ◽

Correction Terms ◽

Cylindrical Collapse ◽

Fluid Parameters

This paper investigates the dynamics of charged cylindrical collapse with the dissipative matter configuration in f(R,TαβTαβ) theory. This newly formulated theory resolves the primordial singularity and provides feasible cosmological results in the early universe.Moreover, its implications occur in high curvature regime where the deviations of energy-momentum squared gravity from general relativity is confirmed. We establish dynamical and transport equations through the Misner–Sharp and Mu¨ler–Israel Stewart techniques, respectively. We then couple these equations to examine the impact of effective fluid parameters and correction terms on the collapsing phenomenon. A connection between the modified terms, matter parameters, and Weyl tensor is also developed. To obtain conformal flatness, we choose a particular model of this theory and assume that dust matter with zero charge leads to conformal flatness and homogenous energy density. We found that the modified terms, dissipative matter, and electromagnetic field reduce the collapsing phenomenon.

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A Study of Charged Cylindrical Gravitational Collapse with Dissipative Fluid

Advances in High Energy Physics ◽

10.1155/2017/8786791 ◽

2017 ◽

Vol 2017 ◽

pp. 1-8 ◽

Cited By ~ 3

Author(s):

Sanjukta Chakraborty ◽

Subenoy Chakraborty

Keyword(s):

Heat Flux ◽

Transport Equation ◽

Gravitational Collapse ◽

Thermodynamic Theory ◽

Anisotropic Fluid ◽

Heat Conducting ◽

Dynamical Equations ◽

Viscous Heat ◽

Dissipative Fluid ◽

Cylindrical Collapse

The present works deals with gravitational collapse of cylindrical viscous heat conducting anisotropic fluid following the work of Misner and Sharp. Using Darmois matching conditions, the dynamical equations are derived and the effects of charge and dissipative quantities over the cylindrical collapse are analyzed. Finally, using the Miller-Israel-Steward causal thermodynamic theory, the transport equation for heat flux is derived and its influence on collapsing system has been studied.

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Charged bulk viscous cylindrical collapse in f(R) theory

International Journal of Modern Physics D ◽

10.1142/s021827181850013x ◽

2018 ◽

Vol 27 (02) ◽

pp. 1850013 ◽

Cited By ~ 4

Author(s):

M. Sharif ◽

Naila Farooq

Keyword(s):

Transport Equation ◽

Source Terms ◽

Dynamical Equations ◽

Cylindrical Model ◽

Bulk Viscous ◽

Dissipative Fluid ◽

Collapse Rate ◽

Cylindrical Collapse

In this paper, we investigate the dynamics of charged cylindrical stellar collapsing model filled with bulk viscous dissipative fluid in [Formula: see text] gravity. For this purpose, we formulate dynamical equations through Misner–Sharp technique and derive transport equation. Finally, we analyze the collapse rate by coupling the transport and dynamical equations. It is concluded that the collapse rate of charged cylindrical model slows down under the influence of dark source terms and matter variables.

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Pseudo-Z symmetric space-times with divergence-free Weyl tensor and pp-waves

International Journal of Geometric Methods in Modern Physics ◽

10.1142/s0219887816500158 ◽

2016 ◽

Vol 13 (02) ◽

pp. 1650015 ◽

Cited By ~ 9

Author(s):

Carlo Alberto Mantica ◽

Young Jin Suh

Keyword(s):

Symmetric Space ◽

Weyl Tensor ◽

Killing Vector ◽

Complete Classification ◽

Space Time ◽

Conformal Killing ◽

Conformally Flat ◽

Conformal Curvature ◽

Wave Space ◽

Divergence Free

In this paper we present some new results about [Formula: see text]-dimensional pseudo-Z symmetric space-times. First we show that if the tensor Z satisfies the Codazzi condition then its rank is one, the space-time is a quasi-Einstein manifold, and the associated 1-form results to be null and recurrent. In the case in which such covector can be rescaled to a covariantly constant we obtain a Brinkmann-wave. Anyway the metric results to be a subclass of the Kundt metric. Next we investigate pseudo-Z symmetric space-times with harmonic conformal curvature tensor: a complete classification of such spaces is obtained. They are necessarily quasi-Einstein and represent a perfect fluid space-time in the case of time-like associated covector; in the case of null associated covector they represent a pure radiation field. Further if the associated covector is locally a gradient we get a Brinkmann-wave space-time for [Formula: see text] and a pp-wave space-time in [Formula: see text]. In all cases an algebraic classification for the Weyl tensor is provided for [Formula: see text] and higher dimensions. Then conformally flat pseudo-Z symmetric space-times are investigated. In the case of null associated covector the space-time reduces to a plane wave and results to be generalized quasi-Einstein. In the case of time-like associated covector we show that under the condition of divergence-free Weyl tensor the space-time admits a proper concircular vector that can be rescaled to a time like vector of concurrent form and is a conformal Killing vector. A recent result then shows that the metric is necessarily a generalized Robertson–Walker space-time. In particular we show that a conformally flat [Formula: see text], [Formula: see text], space-time is conformal to the Robertson–Walker space-time.

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Gravitational collapse of a massive sphere of constant energy density

Astrophysics and Space Science ◽

10.1007/bf00636766 ◽

1988 ◽

Vol 143 (1) ◽

pp. 187-191

Author(s):

M. C. Durgapal ◽

A. K. Pande

Keyword(s):

Energy Density ◽

Gravitational Collapse ◽

Constant Energy ◽

Constant Energy Density

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NEGATIVE ENERGY DENSITY IN SPINNING MATTER SOURCES IN WORMHOLE SPACE–TIMES WITH TORSION

Modern Physics Letters A ◽

10.1142/s0217732398003260 ◽

1998 ◽

Vol 13 (38) ◽

pp. 3069-3072

Author(s):

L. C. GARCIA DE ANDRADE

Keyword(s):

Energy Density ◽

Spin Density ◽

Gravitational Collapse ◽

Negative Pressure ◽

Negative Energy ◽

Space Time ◽

Negative Energy Density ◽

Traversable Wormholes ◽

Radial Tension

Negative energy densities in spinning matter sources of non-Riemannian ultrastatic traversable wormholes require the spin energy density to be higher than the negative pressure or the radial tension. Since the radial tension necessary to support wormholes is higher than the spin density in practice, it seems very unlikely that wormholes supported by torsion may exist in nature. This result corroborates earlier results by Soleng against the construction of the closed time-like curves (CTC) in space–time geometries with spin and torsion. It also agrees with earlier results by Kerlick according to which Einstein–Cartan (EC) gravity torsion sometimes enhance the gravitational collapse instead of avoiding it.

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CHILD UNIVERSE UV REGULARIZATION?

International Journal of Modern Physics D ◽

10.1142/s0218271808012243 ◽

2008 ◽

Vol 17 (03n04) ◽

pp. 551-555 ◽

Cited By ~ 4

Author(s):

E. I. GUENDELMAN

Keyword(s):

Black Hole ◽

Energy Density ◽

High Energy ◽

High Energy Density ◽

Field Theories ◽

Minimum Length ◽

Quantum Field Theories ◽

Quantum Field ◽

Gravitational Effects ◽

Black Hole Evaporation

It is argued that high energy density excitations, responsible for UV divergences in quantum field theories, including quantum gravity, are likely to be the source of child universes which carry them out of the original space–time. This decoupling prevents the high UV excitations from having any influence on physical amplitudes. Child universe production could therefore be responsible for UV regularization in quantum field theories which take into account gravitational effects. Finally, we discuss child universe production in the last stages of black hole evaporation, the prediction of the absence of trans-Planckian primordial perturbations, the connection with the minimum length hypothesis, and in particular the connection with the maximal curvature hypothesis.

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Cylindrically symmetric relativistic fluids and the purely electric Weyl tensor

International Journal of Geometric Methods in Modern Physics ◽

10.1142/s0219887815501030 ◽

2015 ◽

Vol 12 (10) ◽

pp. 1550103 ◽

Cited By ~ 2

Author(s):

Rajesh Kumar ◽

S. K. Srivastava ◽

V. C. Srivastava

Keyword(s):

General Relativity ◽

Energy Density ◽

Weyl Tensor ◽

Einstein’S Equations ◽

Relativistic Fluids ◽

Einstein's Equations ◽

Cylindrically Symmetric ◽

Expansion Scalar

In General Relativity (GR), the analysis of electric and magnetic Weyl tensors has been studied by various authors. The present study deals with cylindrically symmetric relativistic fluids in GR characterized by the vanishing of magnetic Weyl tensor-purely electric (PE) fields. A very new assumption has been adapted to solve the Einstein's equations and the obtained solution is shearing at all. We signified the importance of PE fields in the context of expansion scalar, energy density, shear and acceleration.

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