scholarly journals New developments on structure formation in Chaplygin gas cosmological models

2009 ◽  
Author(s):  
Sandro Silva ◽  
Marceliano Eduardo de Oliveira
Keyword(s):  
Structure Formation ◽  
Chaplygin Gas ◽  
Cosmological Models ◽  
New Developments

scholarly journals Late Time Attractors of Some Varying Chaplygin Gas Cosmological Models

Symmetry ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 769
Author(s):  
Martiros Khurshudyan ◽  
Ratbay Myrzakulov
Keyword(s):  
Dark Energy ◽  
Gravitational Interaction ◽  
Chaplygin Gas ◽  
Cosmological Models ◽  
Late Time ◽  
Time Behavior ◽  
Coincidence Problem ◽  
Energy Models ◽  
Non Linear ◽  
Bayesian Machine Learning

The goal of this paper is to study new cosmological models where the dark energy is a varying Chaplygin gas. This specific dark energy model with non-linear EoS had been often discussed in modern cosmology. Contrary to previous studies, we consider new forms of non-linear non-gravitational interaction between dark matter and assumed dark energy models. We applied the phase space analysis allowing understanding the late time behavior of the models. It allows demonstrating that considered non-gravitational interactions can solve the cosmological coincidence problem. On the other hand, we applied Bayesian Machine Learning technique to learn the constraints on the free parameters. In this way, we gained a better understanding of the models providing a hint which of them can be ruled out. Moreover, the learning based on the simulated expansion rate data shows that the models cannot solve the H0 tension problem.

scholarly journals Viscous dissipative Chaplygin gas dominated homogenous and isotropic cosmological models

2008 ◽  
Vol 77 (6) ◽  
Author(s):  
C. S. J. Pun ◽  
L. Á. Gergely ◽  
M. K. Mak ◽  
Z. Kovács ◽  
G. M. Szabó ◽  
...  
Keyword(s):  
Chaplygin Gas ◽  
Cosmological Models

scholarly journals Observational Constraints on Cosmological Models

1995 ◽  
Vol 148 ◽  
pp. 470-477
Author(s):  
T. Padmanabhan
Keyword(s):  
Power Spectrum ◽  
Structure Formation ◽  
Cosmological Models ◽  
Observational Constraints

AbstractCosmological models for structure formation are severely constrained by several of the recent observational results. We now have observations which probe the power spectrum of fluctuations from about 0.5 h−1 Mpc to 3000 h−1 Mpc. These probes and the constraints they imply on models for structure formation are reviewed.

scholarly journals Scalar models for the generalized Chaplygin gas and the structure formation constraints

2011 ◽  
Vol 17 (3) ◽  
pp. 259-271 ◽  
Author(s):  
Júlio C. Fabris ◽  
Thaisa C. da C. Guio ◽  
Mahamadou Hamani Daouda ◽  
Oliver F. Piattella
Keyword(s):  
Structure Formation ◽  
Chaplygin Gas ◽  
Generalized Chaplygin Gas

scholarly journals RASTALL COSMOLOGY

2012 ◽  
Vol 18 ◽  
pp. 67-76 ◽  
Author(s):  
JÚLIO C. FABRIS ◽  
OLIVER F. PIATTELLA ◽  
DAVI C. RODRIGUES ◽  
CARLOS E. M. BATISTA ◽  
MAHAMADOU H. DAOUDA
Keyword(s):  
Scalar Field ◽  
Observational Data ◽  
Canonical Form ◽  
Conservation Law ◽  
Chaplygin Gas ◽  
Cosmological Models ◽  
The Self ◽  
Generalized Chaplygin Gas ◽  
Field Representation ◽  
Theory Of Gravity

We review the difficulties of the generalized Chaplygin gas model to fit observational data, due to the tension between background and perturbative tests. We argue that such issues may be circumvented by means of a self-interacting scalar field representation of the model. However, this proposal seems to be successful only if the self-interacting scalar field has a non-canonical form. The latter can be implemented in Rastall's theory of gravity, which is based on a modification of the usual matter conservation law. We show that, besides its application to the generalized Chaplygin gas model, other cosmological models based on Rastall's theory have many interesting and unexpected new features.

scholarly journals Spherical "Top-Hat" collapse in a modified Chaplygin gas dominated universe

2015 ◽  
Vol 24 (07) ◽  
pp. 1550050 ◽  
Author(s):  
S. Karbasi ◽  
H. Razmi
Keyword(s):  
Equation Of State ◽  
Structure Formation ◽  
Observational Data ◽  
Chaplygin Gas ◽  
Modified Chaplygin Gas ◽  
Time Rate ◽  
Generalized Chaplygin Gas ◽  
The Stability ◽  
Perturbation Growth ◽  
Good Agreement

Considering perturbation growth in spherical Top-Hat (STH) model of structure formation in a generalized Chaplygin gas (GCG) dominated universe, we want to study this scenario with modified Chaplygin gas (MCG) obeying an equation of state p = A - B/ρα model. Different parameters of this scenario for positive and negative values of A are computed. The evolution of background and collapsed region parameters are found for different cases. The stability of the model and the collapse time rate are considered in different cases. The turn-around redshifts for different values of α are computed; the results are in relatively good agreement with current observational data.

scholarly journals INHOMOGENEOUS COSMOLOGICAL MODELS AND H0 OBSERVATIONS

2012 ◽  
Vol 21 (12) ◽  
pp. 1250085 ◽  
Author(s):  
ANTONIO ENEA ROMANO
Keyword(s):  
Exact Solution ◽  
Perturbation Theory ◽  
Dark Energy ◽  
Equation Of State ◽  
Structure Formation ◽  
Cosmological Models ◽  
Implicit Assumption ◽  
Dimensionless Parameters ◽  
Inhomogeneous Cosmological Models ◽  
Einstein's Equation

We address some recent erroneous claim that H0 observations are difficult to accommodate with LTB cosmological models, showing how to construct solutions in agreement with an arbitrary value of H0 by rewriting the exact solution in terms of dimensionless parameters and functions. This approach can be applied to fully exploit LTB solutions in designing models alternative to dark energy without making any restrictive or implicit assumption about the inhomogeneity profile. The same solution can also be used to study structure formation in the regime in which perturbation theory is not enough and an exact solution of the Einstein's equation is required, or to estimate the effects of a local inhomogeneities on the apparent equation of state of dark energy.

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