Interacting extended Chaplygin gas cosmology in Lyra Manifold

The subject of our interest is an extended Chaplygin gas cosmology. In Literature a variety of cosmological models exist studying the behavior of the universe in the presence of the Chaplygin gas. From its initial form Chaplygin gas evolved and accepted different EoS-s and we will work with one of them. The main purpose of this work is to study behavior of the universe in Lyra Manifold with a varying Effective $\Lambda$-Term, which gives us modified field equations. We are also interested in the behavior of the universe in the case of an existing coupling between the quintessence DE and extended Chaplygin gas. We applied observational constraints and causality issue on our model to separate physically relevant behavior of the phenomenological model

Higher order corrections of the extended Chaplygin gas cosmology with varying GG and Λ\Lambda

In this paper, we study two different models of dark energy based on Chaplygin gas equation of state. The first model is the variable modified Chaplygin gas while the second one is the extended Chaplygin gas. Both models are considered in the framework of higher order $f(R)$ modified gravity. We also consider the case of time varying gravitational constant $G$ and $\Lambda$ for both models. We investigate some cosmological parameters such as the Hubble, the deceleration and the equation of state parameters. Then we showed that the model that we considered, extended Chaplygin gas with time-dependent $G$ and $\Lambda$, is consistent with the observational data. Finally we conclude with the discussion of cosmological perturbations of our model.Comment: Perturbation analysis added, typos corrected, references adde

Viscous Modified Cosmic Chaplygin Gas Cosmology

In this paper we construct modified cosmic Chaplygin gas which has viscosity. We use exponential function method to solve non-linear equation and obtain time-dependent dark energy density. Then discuss Hubble expansion parameter and scale factor and fix them by using observational data. We also investigate stability of this theory

Constraints on interacting dark energy models through cosmic chronometers and Gaussian process

Energy flows between dark energy and dark matter may alleviate the Hubble tension and mitigate the coincidence problem. In this paper, after reconstructing the redshift evolution of the Hubble function by adopting Gaussian process techniques, we estimate the best-fit parameters for some flat Friedmann cosmological models based on a Modified Chaplygin Gas interacting with dark matter. In fact, the expansion history of the Universe will be investigated because passively evolving early galaxies constitute cosmic chronometers. An estimate for the present-day values of the deceleration parameter, adiabatic speed of sound within the dark energy fluid, effective dark energy, and dark matter equation of state parameters is provided. By this, we mean that the interaction term between the two dark fluids, which breaks the Bianchi symmetries, will be interpreted as an effective contribution to the dark matter pressure similarly to the framework of the \lq\lq Generalized Dark Matter". Fixing a certain value for the dark matter abundance at the present day as initial condition will allow us to investigate whether the estimate of the Hubble constant is sensitive to the dark matter - dark energy coupling. We will also show that the cosmic chronometers data favor a hot dark matter, and that our findings are in agreement with the Le Ch\^atelier-Braun principle according to which dark energy should decay into dark matter (and not vice versa).Comment: 14 pages, 2 figure

Logarithmic corrected F(R)F(R) gravity in the light of Planck 2015

In this letter, we consider the theory of $F(R)$ gravity with the lagrangian density $\pounds = R+\alpha R^2 + \beta R^2 \ln \beta R$. We obtain the constant curvature solutions and find the scalar potential of the gravitational field. We also obtain the mass squared of a scalaron in the Einstein$^,$s frame. We find cosmological parameters corresponding to the recent Plank 2015 results. Finally, we analyze the critical points and stability of the new modified theory of gravity and find that logarithmic correction is necessary to have successful model.Comment: arXiv admin note: text overlap with arXiv:1502.00659 by other author