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.

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.

Five-dimensional spherical symmetric perfect fluid collapse in f(R, T) gravity

2019 ◽  
Vol 97 (6) ◽  
pp. 637-643
Author(s):  
M. Jamil Amir ◽  
Sadia Sattar
Keyword(s):  
Black Hole ◽  
Perfect Fluid ◽  
Spherically Symmetric ◽  
Junction Conditions ◽  
Field Equations ◽  
Interior Region ◽  
Exterior Region ◽  
Modified Theory Of Gravity ◽  
Apparent Horizons ◽  
Modified Theory

This paper contains the study of spherically symmetric perfect fluid collapse in the framework of f(R, T) modified theory of gravity using five-dimensional background. We consider the five-dimensional spherical symmetric metric as the interior region and a five-dimensional Schwarzschild metric as an exterior region. The Darmois junction conditions between exterior and interior regions are discussed. By taking the particular f(R, T) model, the corresponding field equations are evaluated for both marginally bound L(r) = 1 and non-marginally bound L(r) ≠ 1 cases. We find the gravitational mass of the collapsing system and discuss the apparent horizons and their time formation for different possible cases. Also, the cosmological and black hole horizons have been discussed. It has been concluded that the term involving λ plays a double role: it accelerates the collapse in the region where ρ0 < 4p0 and it slows down the collapsing of matter when ρ0 > 4p0. Further, it is noted that our results reduce to the results found by Sharif and Ahmad (J. Korean Phys. Soc. 52, 980 (2008). doi: 10.3938/jkps.52.980) in general relativity for λ = 0.

scholarly journals Apparent horizons of anN-black-hole system in a space-time with a cosmological constant

1993 ◽  
Vol 47 (8) ◽  
pp. 3203-3213 ◽  
Author(s):  
Ken-ichi Nakao ◽  
Kazuhiro Yamamoto ◽  
Kei-ichi Maeda
Keyword(s):  
Black Hole ◽  
Cosmological Constant ◽  
Space Time ◽  
Apparent Horizons

scholarly journals HORIZONS IN MATTER: BLACK HOLE HAIR VERSUS NULL BIG BANG

2009 ◽  
Vol 18 (14) ◽  
pp. 2283-2287 ◽  
Author(s):  
K. A. BRONNIKOV ◽  
OLEG B. ZASLAVSKII
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Cosmological Constant ◽  
Cosmic Strings ◽  
Density Ratio ◽  
Radial Pressure ◽  
Big Bang ◽  
Spherically Symmetric ◽  
Normal Matter ◽  
Phantom Matter

It is shown that only particular kinds of matter (in terms of the "radial" pressure-to-density ratio w) can coexist with Killing horizons in black hole or cosmological space–times. Thus, for arbitrary (not necessarily spherically symmetric) static black holes, admissible are vacuum matter (w = −1, i.e. the cosmological constant or its generalization with the same value of w) and matter with certain values of w between 0 and −1, in particular a gas of disordered cosmic strings (w = −1/3). If the cosmological evolution starts from a horizon (the so-called null big bang scenarios), this horizon can coexist with vacuum matter and certain kinds of phantom matter with w ≤ −3. It is concluded that normal matter in such scenarios is entirely created from vacuum.

scholarly journals Shadow cast by a rotating and nonlinear magnetic-charged black hole in perfect fluid dark matter

2021 ◽  
pp. 2150112
Author(s):  
Tian-Chi Ma ◽  
He-Xu Zhang ◽  
Peng-Zhang He ◽  
Hao-Ran Zhang ◽  
Yuan Chen ◽  
...  
Keyword(s):  
Black Hole ◽  
Dark Matter ◽  
Perfect Fluid ◽  
Emission Rate ◽  
Magnetic Charge ◽  
Spherically Symmetric ◽  
Intensity Parameter ◽  
Shadow Cast ◽  
Sgr A ◽  
Charge Formula

In this paper, we derived an exact solution of the spherically symmetric Hayward black hole surrounded by perfect fluid dark matter (PFDM). By applying the Newman–Janis algorithm, we generalized it to the corresponding rotating black hole. Then, we studied the shadows of rotating Hayward black hole in PFDM. The apparent shape of the shadow depends upon the black hole spin [Formula: see text], the magnetic charge [Formula: see text] and the PFDM intensity parameter [Formula: see text]. The shadow is a perfect circle in the non-rotating case [Formula: see text] and a deformed one in the rotating case [Formula: see text]. For a fixed value of [Formula: see text], the size of the shadow increases with the increasing [Formula: see text], but decreases with the increasing [Formula: see text]. We further investigated the black hole emission rate. We found that the emission rate decreases with the increasing [Formula: see text] (or [Formula: see text]) and the peak of the emission shifts to lower frequency. Finally, we discussed the observational prospects corresponding to the supermassive black hole Sgr A[Formula: see text] at the center of the Milky Way.

Gravitational collapse in f(R) theories of gravity with non-minimal coupling

2019 ◽  
Vol 34 (03) ◽  
pp. 1950025 ◽  
Author(s):  
H. Nazar ◽  
G. Abbas
Keyword(s):  
Perfect Fluid ◽  
Gravitational Collapse ◽  
Spherically Symmetric ◽  
Coupling Constant ◽  
Minimal Coupling ◽  
Apparent Horizons ◽  
Exterior Regions ◽  
Theories Of Gravity ◽  
Minimal Curvature ◽  
Zero Coupling

The purpose of this paper is to discuss the perfect fluid gravitational collapse in modified f(R) metric gravity theories with non-minimal curvature coupled to matter. For this inference, we investigate the effects on self-gravitating implosion with spherically symmetric non-static geometry in the presence of extra force [Formula: see text], that express the cosmic expansion with dark source constraints. Matching conditions are given in which we have taken the insertion of non-static interior and static exterior regions along with cosmological constant. We have investigated the apparent horizons with effective results and along with their physical interpretation. It is analyzed that the extra component of dark source material reduces the gravitating implosion, hence slowing the rate of collapse. This study also reflects the contribution towards the perfect fluid for the generalization in f(R) gravity with zero coupling constant [Formula: see text].

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