Static spherically-symmetric perfect fluids with pressure equal to energy density

1991 ◽  
Vol 186 (2) ◽  
pp. 331-336 ◽  
Author(s):  
R. B. S. Yadav ◽  
S. L. Saini
Keyword(s):  
Energy Density ◽  
Spherically Symmetric ◽  
Perfect Fluids

A NONSINGULAR PERFECT FLUID CLASSICAL LEPTON MODEL OF ARBITRARILY SMALL RADIUS

2013 ◽  
Vol 22 (14) ◽  
pp. 1350088 ◽  
Author(s):  
THOMAS E. KIESS
Keyword(s):  
Electric Field ◽  
Perfect Fluid ◽  
Small Radius ◽  
Spherically Symmetric ◽  
Model Based ◽  
Perfect Fluids ◽  
General Relativistic ◽  
Relativistic Models ◽  
Lepton Model

We exhibit a classical lepton model based on a perfect fluid that reproduces leptonic charges and masses in arbitrarily small volumes without metric singularities or pressure discontinuities. This solution is the first of this kind to our knowledge, because to date the only classical general relativistic models that have reproduced leptonic charges and masses in arbitrarily small volumes are based on imperfect (anisotopic) fluids or perfect fluids with electric field discontinuities. We use a Maxwell–Einstein exact metric for a spherically symmetric static perfect fluid in a region in which the pressure vanishes at a boundary, beyond which the metric is of the Reissner–Nordström form. This construction models lepton mass and charge in the limit as the boundary → 0.

HOLOGRAPHIC SPHERICALLY SYMMETRIC METRICS

2007 ◽  
Vol 16 (06) ◽  
pp. 1603-1641 ◽  
Author(s):  
MICHAEL PETRI
Keyword(s):  
Energy Density ◽  
Degrees Of Freedom ◽  
Mass Density ◽  
Entropy Density ◽  
Constant Factor ◽  
Spherically Symmetric ◽  
Scale Invariant ◽  
Total Energy Density ◽  
Boundary Area ◽  
Symmetric Metrics

The holographic principle (HP) conjectures, that the maximum number of degrees of freedom of any realistic physical system is proportional to the system's boundary area. The HP has its roots in the study of black holes. It has recently been applied to cosmological solutions. In this article we apply the HP to spherically symmetric static space-times. We find that any regular spherically symmetric object saturating the HP is subject to tight constraints on the (interior) metric, energy-density, temperature and entropy-density. Whenever gravity can be described by a metric theory, gravity is macroscopically scale invariant and the laws of thermodynamics hold locally and globally, the (interior) metric of a regular holographic object is uniquely determined up to a constant factor and the interior matter-state must follow well defined scaling relations. When the metric theory of gravity is general relativity, the interior matter has an overall string equation of state (EOS) and a unique total energy-density. Thus the holographic metric derived in this article can serve as simple interior 4D realization of Mathur's string fuzzball proposal. Some properties of the holographic metric and its possible experimental verification are discussed. The geodesics of the holographic metric describe an isotropically expanding (or contracting) universe with a nearly homogeneous matter-distribution within the local Hubble volume. Due to the overall string EOS the active gravitational mass-density is zero, resulting in a coasting expansion with Ht = 1, which is compatible with the recent GRB-data.

scholarly journals SELFGRAVITATION IN A GENERAL-RELATIVISTIC ACCRETION OF STEADY FLUIDS

2007 ◽  
Vol 04 (01) ◽  
pp. 197-208 ◽  
Author(s):  
BOGUSZ KINASIEWICZ ◽  
PATRYK MACH ◽  
EDWARD MALEC
Keyword(s):  
Total Mass ◽  
Accretion Rate ◽  
The Other ◽  
Newtonian Gravity ◽  
Spherically Symmetric ◽  
Steady Flows ◽  
Fluid Content ◽  
Mass Accretion Rate ◽  
Perfect Fluids ◽  
General Relativistic

The selfgravity of an infalling gas can alter significantly the accretion of gases. In the case of spherically symmetric steady flows of polytropic perfect fluids the mass accretion rate achieves maximal value when the mass of the fluid is 1/3 of the total mass. There are two weakly accreting regimes, one over-abundant and the other poor in fluid content. The analysis within the newtonian gravity suggests that selfgravitating fluids can be unstable, in contrast to the accretion of test fluids.

scholarly journals Stability of spherically symmetric timelike thin-shells in general relativity with a variable equation-of-state

2017 ◽  
Vol 26 (14) ◽  
pp. 1750158 ◽  
Author(s):  
S. Habib Mazharimousavi ◽  
M. Halilsoy ◽  
S. N. Hamad Amen
Keyword(s):  
General Relativity ◽  
Equation Of State ◽  
Energy Density ◽  
Surface Energy ◽  
Thin Shell ◽  
Minkowski Spacetime ◽  
Thin Shells ◽  
Spherically Symmetric ◽  
Surface Energy Density ◽  
Variable Equation

We study spherically symmetric timelike thin-shells in [Formula: see text]-dimensional bulk spacetime with a variable equation-of-state for the fluid presented on the shell. In such a fluid, the angular pressure [Formula: see text] is a function of both surface energy density [Formula: see text] and the radius [Formula: see text] of the thin-shell. Explicit cases of the thin shells connecting two nonidentical cloud of strings spacetimes and a flat Minkowski spacetime to the Schwarzschild metric are investigated.

scholarly journals Nonstatic Spherically Symmetric Isotropic Solutions for a Perfect Fluid in General Relativity

1978 ◽  
Vol 31 (1) ◽  
pp. 111 ◽  
Author(s):  
Max Wyman
Keyword(s):  
Differential Equation ◽  
General Relativity ◽  
General Solution ◽  
Present Author ◽  
Spherically Symmetric ◽  
Einstein Field Equations ◽  
Field Equations ◽  
Perfect Fluids ◽  
Specific Choice ◽  
Total Differential

The present author (Wyman 1946) showed that all perfect fluids which can be represented by nonstatic, spherically symmetric, isotropic solutions of the Einstein field equations can be found by solving a nonlinear total differential equation of the second order involving. an arbitrary function 'P(r). Since then several particular solutions of this equation have been found. Although the four solutions given recently by Chakravarty et at. (1976) involve particular choices of 'P(r), none of these is the general solution of the equation that results from the specific choice of 'P(r) that was made. The present paper shows how these four general solutions are obtained.

scholarly journals Genericity aspects of black hole formation in the collapse of spherically symmetric slightly inhomogeneous perfect fluids

2016 ◽  
Vol 25 (02) ◽  
pp. 1650023 ◽  
Author(s):  
Seema Satin ◽  
Daniele Malafarina ◽  
Pankaj S. Joshi
Keyword(s):  
Black Hole ◽  
Perfect Fluid ◽  
Naked Singularity ◽  
Spherically Symmetric ◽  
Final State ◽  
Naked Singularities ◽  
Perfect Fluids ◽  
Special Cases ◽  
Collapse Models ◽  
Mass Profile

We study the complete gravitational collapse of a class of spherically symmetric inhomogeneous perfect fluid models obtained by introducing small radial perturbations in an otherwise homogeneous matter cloud. Our aim here is to study the genericity and stability of the formation of black holes and locally naked singularities in collapse. While the occurrence of naked singularities is known for many models of collapse, the key issue now in focus is genericity and stability of these outcomes. Towards this purpose, we study how the introduction of a somewhat general class of small inhomogeneities in homogeneous collapse leading to a black hole can change the final outcome to a naked singularity. The key feature that we assume for the perturbation profile is that of a mass profile that is separable in radial and temporal coordinates. The known models of dust and homogeneous perfect fluid collapse can be obtained from this choice of the mass profile as special cases. This choice is very general and physically well motivated and we show that this class of collapse models leads to the formation of a naked singularity as the final state.

SYMMETRY CHANGES DURING THE EVOLUTION OF THE UNIVERSE

1990 ◽  
Vol 05 (31) ◽  
pp. 2593-2598 ◽  
Author(s):  
METIN ARIK ◽  
MUHITTIN MUNGAN
Keyword(s):  
Energy Density ◽  
Spatial Structure ◽  
Spherically Symmetric ◽  
Evolution Of The Universe ◽  
The Universe ◽  
Kaluza Klein ◽  
Symmetry Change

This article investigates a (2 + 1)-dimensional universe evolving from a spherically symmetric spatial structure into the Kaluza-Klein structure. The implications of the symmetry change are discussed for this model in particular and also in general. It turns out that for such symmetry changes, the energy density is ill-defined for early times.

Modification of gravity by a spherically symmetric wormhole

2017 ◽  
Vol 26 (13) ◽  
pp. 1750145 ◽  
Author(s):  
A. A. Kirillov ◽  
E. P. Savelova
Keyword(s):  
Energy Density ◽  
Newtonian Potential ◽  
Spherically Symmetric ◽  
Conformal Invariant ◽  
Invariant Equation ◽  
Polarization Energy ◽  
Newton's Law ◽  
Newton’S Law

We examine corrections to the standard Newton's law due to the presence of a spherically symmetric wormhole. We show that the Newtonian potential can be decomposed into two terms. The first term does not depend on the wormhole metric and corresponds to the standard law. It obeys to the conformal invariant equation. The second term explicitly depends on the wormhole metric and corresponds to corrections. We show that such corrections can be described in terms of a polarization energy density.

scholarly journals Scalar and vector perturbations in a universe with nonlinear perfect fluid

2021 ◽  
Vol 81 (3) ◽  
Author(s):  
Ezgi Canay ◽  
Ruslan Brilenkov ◽  
Maxim Eingorn ◽  
A. Savaş Arapoğlu ◽  
Alexander Zhuk
Keyword(s):  
Energy Density ◽  
Perfect Fluid ◽  
Nonlinear Equations ◽  
Equations Of State ◽  
Cosmological Models ◽  
Perfect Fluids ◽  
Screening Approach ◽  
Linear And Nonlinear ◽  
Discrete Inhomogeneities

AbstractWe study a three-component universe filled with dust-like matter in the form of discrete inhomogeneities (e.g., galaxies) and perfect fluids characterized by linear and nonlinear equations of state. Within the cosmic screening approach, we develop the theory of scalar and vector perturbations. None of the energy density contrasts associated with the distinct components is treated as small. Consequently, the derived equations are valid at both sub- and super-horizon scales and enable simulations for a variety of cosmological models.

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