scholarly journals EXTENDED SPHERICAL COLLAPSE AND THE ACCELERATING UNIVERSE

2013 ◽  
Vol 22 (08) ◽  
pp. 1350038 ◽  
Author(s):  
A. DEL POPOLO ◽  
F. PACE ◽  
J. A. S. LIMA
Keyword(s):  
Shear Stress ◽  
Angular Momentum ◽  
Linear Density ◽  
Accelerating Universe ◽  
De Sitter ◽  
Local Rotation ◽  
Spherical Collapse ◽  
Collapse Model ◽  
Density Threshold

The influence of the shear stress and angular momentum on the nonlinear spherical collapse model is discussed in the framework of the Einstein–de Sitter and ΛCDM models. By assuming that the vacuum component is not clustering within the homogeneous nonspherical overdensities, we show how the local rotation and shear affect the linear density threshold for collapse of the nonrelativistic component (δc) and its virial overdensity (ΔV). It is also found that the net effect of shear and rotation in galactic scale is responsible for higher values of the linear overdensity parameter as compared with the standard spherical collapse model (no shear and rotation).

Improvements in the Spherical Collapse Model and Dark Energy Cosmologies

2014 ◽  
Vol 23 (3-4) ◽  
Author(s):  
A. Del Popolo
Keyword(s):  
Shear Stress ◽  
Angular Momentum ◽  
Dark Energy ◽  
Spherical Symmetry ◽  
Linear Density ◽  
Spherical Collapse ◽  
Collapse Model ◽  
Density Threshold ◽  
Stress Influence

AbstractIn the present paper, we study how the effects of deviations from spherical symmetry of a system, produced by angular momentum, and shear stress, influence typical parameters of the spherical collapse model, like the linear density threshold for collapse of the non-relativistic component (

scholarly journals Angular momentum in cluster Spherical Collapse Model

2011 ◽  
Vol 417 (4) ◽  
pp. 2554-2561 ◽  
Author(s):  
Guido Cupani ◽  
Marino Mezzetti ◽  
Fabio Mardirossian
Keyword(s):  
Angular Momentum ◽  
Spherical Collapse ◽  
Collapse Model

scholarly journals A precise mass function in the excursion set approach

2017 ◽  
Vol 26 (1) ◽  
Author(s):  
Antonino Del Popolo
Keyword(s):  
Angular Momentum ◽  
Cosmological Constant ◽  
Mass Range ◽  
Mass Function ◽  
Dynamical Friction ◽  
Spherical Collapse ◽  
Collapse Model ◽  
Virial Mass ◽  
Excursion Set ◽  
Good Agreement

AbstractIn the present paper, using previous results from Del Popolo papers, we show how the mass function evolution can be obtained in the framework of a spherical collapse model, which has been modified to take account of dynamical friction, the cosmological constant, and angular momentum which proto-structures acquire through tidal interaction with neighbouring ones. We found an improved barrier which is in excellent agreement with simulations. The quoted barrier is used to calculated the mass function. In the case of the ΛCDM paradigm, our mass function is in good agreement (within some %) with the mass function of Klypin’s Bolshoi simulation for the virial mass range 5 × 10

Boundary conditions for Maxwell fields in Kerr-AdS spacetimes

2016 ◽  
Vol 25 (09) ◽  
pp. 1641011 ◽  
Author(s):  
Mengjie Wang
Keyword(s):  
Black Holes ◽  
Angular Momentum ◽  
Boundary Conditions ◽  
Energy Flux ◽  
Momentum Flux ◽  
De Sitter ◽  
Perturbative Methods ◽  
Flux Boundary Conditions ◽  
Maxwell Fields ◽  
New Type

Perturbative methods are useful to study the interaction between black holes and test fields. The equation for a perturbation itself, however, is not complete to study such a composed system if we do not assign physically relevant boundary conditions. Recently we have proposed a new type of boundary conditions for Maxwell fields in Kerr-anti-de Sitter (Kerr-AdS) spacetimes, from the viewpoint that the AdS boundary may be regarded as a perfectly reflecting mirror, in the sense that energy flux vanishes asymptotically. In this paper, we prove explicitly that a vanishing energy flux leads to a vanishing angular momentum flux. Thus, these boundary conditions may be dubbed as vanishing flux boundary conditions.

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