Observational data analysis for generalized cosmic Chaplygin gas in the background of Brans–Dicke theory

In this paper, we have considered the generalized cosmic Chaplygin gas (GCCG) in the background of Brans–Dicke (BD) theory and also assumed that the Universe is filled in GCCG, dark matter and radiation. To investigate the data fitting of model parameters, we have constrained the model using recent observations. Using [Formula: see text] minimum test, the best-fit values of the model parameters are determined by OHD+CMB+BAO+SNIa joint data analysis. We have drawn the contour figures for different confidence levels [Formula: see text], [Formula: see text] and [Formula: see text]. To examine the viability of the GCCG model in BD theory, we have also determined △AIC and △BIC using the information criteria (AIC and BIC). Graphically, we have analyzed the natures of the equation of state parameter and deceleration parameter for our best-fit values of model parameters. Also, we have studied the square speed of sound [Formula: see text] which lies in the interval [Formula: see text] for expansion of the Universe. So, our considered model is classically stable by considering the best-fit values of the model parameters due to the data analysis.

Attractor inflationary solutions in braneworld scenario

This paper is devoted to discuss the attractor solutions of inflationary Chaplygin gas models such as generalized Chaplygin gas, modified Chaplygin gas and generalized cosmic Chaplygin gas in the framework of Randall–Sundrum type II braneworld scenario. We investigate the inflationary parameters like scalar spectral index [Formula: see text], tensor to scalar ratio [Formula: see text], and the running of scalar index [Formula: see text] as a function of e-folding numbers [Formula: see text] in the presence of attractor: [Formula: see text]. We evaluate and reformulate these parameters under high energy condition. In this inflationary scenario, we develop [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] planes. We also found that these cosmological parameters and perturbation strongly agree with the recent Planck data 2018 for considered Chaplygin gas models instead of [Formula: see text] in case of generalized cosmic Chaplygin gas.

Particle Creation and Thermal Aspects of Viscous Generalized Cosmic Chaplygin Gas

We investigate the particle creation, as well as the thermodynamics phenomenon of viscous generalized cosmic Chaplygin gas as a cosmic fluid by assuming the flat FRW universe. For this purpose, we extract various parameters such as the energy density ( ρ ) , Hubble parameter ( H ) , declaration parameter ( q ) , temperature ( T f ) , and particle number density ( n ) in the presence of three different models of the particle creation rate ( Γ ). We discuss the validity of the generalized second law of thermodynamics and thermal equilibrium condition under three models of Γ and discuss the graphical behavior of above-mentioned terms.

Viscous Chaplygin gas models as spherical top-hat collapsing fluids

We study the spherical top-hat collapse in Einstein gravity and loop quantum cosmology (LQC) by taking the nonlinear evolution of viscous modified variable Chaplygin gas (CG) and viscous generalized cosmic chaplygin gas (GCCG). We calculate the equation of state (EoS) parameter, square speed of sound, perturbed (EoS) parameter, perturbed square speed of sound, density contrast and divergence of peculiar velocity in perturbed region and discussed their behavior. It is observed that both CG models support the spherical collapse (SC) in Einstein as well as LQC because density contrast remains positive in both cases and the perturbed EoS parameter remains positive at the present epoch as well as near future. It is remarked here that these parameters provide consistent results for both CG models in both gravities.

Thermodynamics of generalized cosmic Chaplygin gas model

In this paper, we study thermal stability of an exotic fluid known as generalized cosmic Chaplygin gas (GCCG). We evaluate different physical parameters and examine how this fluid describes accelerated expansion of the universe. The stability conditions are formulated from thermodynamics which indicate that the respective fluid is stable adiabatically but it cannot be checked under isothermal condition.