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Register a new userWarm Modified Chaplygin Gas Shaft Inflation
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In this paper, we examine the possible realization of a new family of inflation called shaft inflation by assuming the modified Chaplygin gas model and tachyon scalar field. We also consider the special form of dissipative coefficient as $Gamma={a_0}frac{T^{3}}{phi^{2 }}$ and calculate the various inflationary parameters in the scenario of strong and weak dissipative regimes. In order to examine the behavior of inflationary parameters, the planes of $n_s - phi,~n_s - r$ and $n_s - alpha_s$ (where $n_s,~alpha_s,~r$ and $phi$ represent spectral index, its running, tensor to scalar ratio and scalar field respectively) are being developed which lead to the constraints: $r< 0.11$, $n_s=0.96pm0.025$ and $alpha_s =-0.019pm0.025$. It is quite interesting that these results of inflationary parameters are compatible with BICEP$2$, WMAP $(7+9)$ and recent Planck data.
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We investigate the role of bulk viscous pressure on the warm inflationary modified Chaplygin gas in brane-world framework in the presence of standard scalar field. We assume the intermediate inflationary scenario in strong dissipative regime and constructed the inflaton, potential, entropy density, slow-roll parameters, scalar and tensor power spectra, scalar spectral index and tensor-to-scalar ratio. We develop various trajectories such as $n_s - N$, $n_s - r$ and $n_s - alpha_s$ (where $n_s$ is the spectral index, $alpha_s$ is the running of spectral index, $N$ is the number of e-folds and $r$ is tensor-to-scalar ratio) for variable as well as constant dissipation and bulk viscous coefficients at high dissipative regime. It is interesting to remark here that our results of these parameters are compatible with recent observational data such as WMAP $7+9$, BICEP$2$ and Planck data.
In this paper we study the Chaplygin gas model as a candidate for inflation in the framework of the Randall Sundrum type-II braneworld model. We consider the original and generalized Chaplygin gas model in the presence of monomial potential. The inflationary spectrum perturbation parameters are reformulated and evaluated in the high-energy limit and we found that they depend on several parameters. We also showed that these perturbation parameters are widely compatible with the recent Planck data for a particular choice of the parameters space of the model. A suitable observational central value of $n_{s}simeq $ $0.965$ is also obtained in the case of original and generalized Chaplygin gas.
Unification of dark matter and dark energy as short- and long-range manifestations of a single cosmological substance is possible in models described by the generalized Chaplygin gas equation of state. We show it admits halo-like structures and discuss their density profiles, the resulting space-time geometry and the rotational velocity profiles expected in these models.
The present work employs the Linder parametrization of a constant growth index cite{linder/index} to investigate the evolution of growth rate of clustering and the dissipation of configurational entropy in some of the most widely studied Chaplygin gas models, such as the generalized Chaplygin gas and the modified Chaplygin gas. The model parameters of the Chaplygin gas models are found to play a vital role in the evolution of growth rate, dark energy density parameter, EoS parameter, and configurational entropy. Furthermore, the work communicates the rate of change of configurational entropy to attain a minimum which depend solely on the choice of model parameters and that there exist suitable parameter combinations giving rise to a viable dissipation of configurational entropy, and therefore certifying its time derivative to hit a minimum at a scale factor which complies with the current observational constraints on the redshift of transition from a dust to an accelerated Universe and thereby making Chaplygin gas models a viable candidate for dark energy.
An extension of the Starobinsky model is proposed. Besides the usual Starobinsky Lagrangian, a term proportional to the derivative of the scalar curvature, $ abla_{mu}R abla^{mu}R$, is considered. The analyzis is done in the Einstein frame with the introduction of a scalar field and a vector field. We show that inflation is attainable in our model, allowing for a graceful exit. We also build the cosmological perturbations and obtain the leading-order curvature power spectrum, scalar and tensor tilts and tensor-to-scalar ratio. The tensor and curvature power spectrums are compared to the most recent observations from BICEP2/Keck collaboration. We verify that the scalar-to-tensor rate $r$ can be expected to be up to three times the values predicted by Starobinsky model.
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