scholarly journals The formation of trapped surfaces in the gravitational collapse of spherically symmetric scalar fields with a positive cosmological constant

2020 ◽  
Vol 37 (19) ◽  
pp. 195022
Author(s):  
João L Costa
Keyword(s):  
Cosmological Constant ◽  
Gravitational Collapse ◽  
Scalar Fields ◽  
Spherically Symmetric ◽  
Positive Cosmological Constant ◽  
Trapped Surfaces

scholarly journals EFFECTS OF ELECTROMAGNETIC FIELD ON GRAVITATIONAL COLLAPSE

2009 ◽  
Vol 24 (31) ◽  
pp. 2551-2563 ◽  
Author(s):  
M. SHARIF ◽  
G. ABBAS
Keyword(s):  
Electromagnetic Field ◽  
Cosmological Constant ◽  
Perfect Fluid ◽  
Gravitational Collapse ◽  
Physical Significance ◽  
Spherically Symmetric ◽  
Junction Conditions ◽  
Positive Cosmological Constant ◽  
Symmetric Spacetimes ◽  
Apparent Horizons

In this paper, the effect of electromagnetic field has been investigated on the spherically symmetric gravitational collapse with the perfect fluid in the presence of positive cosmological constant. Junction conditions between the static exterior and non-static interior spherically symmetric spacetimes are discussed. We study the apparent horizons and their physical significance. It is found that electromagnetic field reduces the bound of cosmological constant by reducing the pressure and hence collapsing process is faster as compared to the perfect fluid case. This work gives the generalization of the perfect fluid case to the charged perfect fluid. Results for the perfect fluid case are recovered.

Five-dimensional spherical gravitational collapse of anisotropic fluid with cosmological constant

2017 ◽  
Vol 14 (02) ◽  
pp. 1750025 ◽  
Author(s):  
Suhail Khan ◽  
Hassan Shah ◽  
Ghulam Abbas
Keyword(s):  
Cosmological Constant ◽  
Apparent Horizon ◽  
Physical Significance ◽  
Anisotropic Fluid ◽  
Spherically Symmetric ◽  
Hole Size ◽  
Junction Conditions ◽  
De Sitter ◽  
Positive Cosmological Constant ◽  
Exterior Regions

Our aim is to study five-dimensional spherically symmetric anisotropic collapse with a positive cosmological constant (PCC). For this purpose, five-dimensional spherically symmetric and Schwarzschild–de Sitter metrics are chosen in the interior and exterior regions respectively. A set of junction conditions is derived for the smooth matching of interior and exterior spacetimes. The apparent horizon is calculated and its physical significance is studied. It comes out that the whole collapsing process is influenced by the cosmological constant. The collapsing process under the influence of cosmological constant slows down and black hole size also reduced.

scholarly journals SPHERICALLY SYMMETRIC GRAVITATIONAL COLLAPSE OF A DUST CLOUD IN EINSTEIN–GAUSS–BONNET GRAVITY

2011 ◽  
Vol 26 (28) ◽  
pp. 2135-2147 ◽  
Author(s):  
KANG ZHOU ◽  
ZHAN-YING YANG ◽  
DE-CHENG ZOU ◽  
RUI-HONG YUE
Keyword(s):  
Cosmological Constant ◽  
Gravitational Collapse ◽  
Dust Cloud ◽  
Spherically Symmetric ◽  
Relativistic Case ◽  
Bonnet Gravity ◽  
Profound Influence ◽  
Dimensional Spacetime ◽  
General Relativistic ◽  
Bonnet Term

We explore the gravitational collapse of a spherically symmetric dust cloud in the Einstein–Gauss–Bonnet gravity without a cosmological constant, and obtain three families of LTB-like solutions. It is shown that the Gauss–Bonnet term has a profound influence on the nature of singularities, and the global structure of spacetime changes drastically from the analogous general relativistic case. Interestingly, the formation of a naked, massive and uncentral singularity, allowed in five-dimensional spacetime, is forbidden if D≥6. Moreover, such singularity is gravitational strong and a serious counterexample to CCH.

scholarly journals SPHERICALLY SYMMETRIC MASSIVE SCALAR FIELDS IN GENERAL RELATIVITY

2010 ◽  
Vol 25 (07) ◽  
pp. 1429-1438 ◽  
Author(s):  
MOHAMMAD MEHRPOOYA ◽  
D. MOMENI
Keyword(s):  
Scalar Field ◽  
Cosmological Constant ◽  
Scalar Fields ◽  
Matter Field ◽  
Massless Scalar ◽  
Special Choice ◽  
Spherically Symmetric ◽  
Elementary Functions ◽  
Field Equations ◽  
Tidal Forces

First, we review some attempts made to find the exact spherically symmetric solutions to Einstein field equations in the presence of scalar fields. Wyman's solution in both the static and the nonstatic scalar field is discussed, and it is shown why in the case of the nonstatic homogenous matter field the static metric cannot be represented in terms of elementary functions. We mention here that if the space–time is static, according to field equations, there are two options for fixing the scalar field: static (time-independent) and nonstatic (time-dependent). All these solutions are limited to the minimally coupled massless scalar fields and also in the absence of the cosmological constant. Then we show that if we are interested to have homogenous isotropic scalar field matter, we can construct a series solution in terms of the scalar field's mass and cosmological constant. This solution is static and possesses a locally flat case as a special choice of the mass of the scalar field and can be interpreted as an effective vacuum. Therefore, the mass of the scalar field eliminates any locally gravitational effect as tidal forces. Finally, we describe why this system is unstable in the language of dynamical systems.

scholarly journals THE CONSISTENT NEWTONIAN LIMIT OF EINSTEIN'S GRAVITY WITH A COSMOLOGICAL CONSTANT

2001 ◽  
Vol 10 (05) ◽  
pp. 649-661 ◽  
Author(s):  
MAREK NOWAKOWSKI
Keyword(s):  
Boundary Condition ◽  
General Relativity ◽  
Cosmological Constant ◽  
Mass Distribution ◽  
Newtonian Limit ◽  
Spherically Symmetric ◽  
Maximum Mass ◽  
Finite Range ◽  
Positive Cosmological Constant ◽  
The Poisson Equation

We derive the "exact" Newtonian limit of general relativity with a positive cosmological constant Λ. We point out that in contrast to the case with Λ=0, the presence of a positive Λ in Einsteins's equations enforces, via the condition |Φ|≪1 on the potential Φ, a range ℛ max (Λ)≫r≫ℛ min (Λ), within which the Newtonian limit is valid. It also leads to the existence of a maximum mass, ℳ max (Λ). As a consequence we cannot put the boundary condition for the solution of the Poisson equation at infinity. A boundary condition suitably chosen now at a finite range will then get reflected in the solution of Φ provided the mass distribution is not spherically symmetric.

Final fate of charged anisotropic fluid collapse

2017 ◽  
Vol 32 (35) ◽  
pp. 1750192 ◽  
Author(s):  
Suhail Khan ◽  
Hassan Shah ◽  
Zahid Ahmad ◽  
Muhammad Ramzan
Keyword(s):  
Electromagnetic Field ◽  
Cosmological Constant ◽  
Matter Content ◽  
Repulsive Force ◽  
Anisotropic Fluid ◽  
Time Interval ◽  
Spherically Symmetric ◽  
Positive Cosmological Constant ◽  
Full Agreement ◽  
Theor Phys

This paper studies the effects of charge on spherically symmetric collapse of anisotropic fluid with a positive cosmological constant. It is observed that electromagnetic field places restriction on the bounds of cosmological constant, which acts as repulsive force against the contraction of matter content and hence the rate of destruction is faster in the presence of electromagnetic field. We have also noted that the presence of charge affects the time interval between the formation of cosmological horizon (CH) and black hole horizon (BHH). When the electric field strength E(t, r) vanishes, our investigations are in full agreement with the results obtained by Ahmad and Malik [Int. J. Theor. Phys. 55, 600 (2016)].

GRAVITATIONAL PERFECT FLUID COLLAPSE WITH COSMOLOGICAL CONSTANT

2007 ◽  
Vol 22 (20) ◽  
pp. 1493-1502 ◽  
Author(s):  
M. SHARIF ◽  
ZAHID AHMAD
Keyword(s):  
Black Hole ◽  
Cosmological Constant ◽  
Perfect Fluid ◽  
Physical Significance ◽  
Spherically Symmetric ◽  
Positive Cosmological Constant ◽  
Matching Conditions ◽  
Apparent Horizons ◽  
Dust Case

In this paper, the effect of a positive cosmological constant on spherically symmetric collapse with perfect fluid has been investigated. The matching conditions between static exterior and non-static interior spacetimes are given in the presence of a cosmological constant. We also study the apparent horizons and their physical significance. It is concluded that the cosmological constant slows down the collapse of matter and hence limit the size of the black hole. This analysis gives the generalization of the dust case to the perfect fluid. We recover the results of the dust case for p = 0.

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