In this paper we consider a new version of Chaplygin gas cosmology that includes bulk viscosity and a varying gravitational constant. This new model of Chaplygin gas allows us to recover a barotropic fluid with a quadratic equation of state. Bulk viscosity is assumed to be a power law function of the energy density. We study the evolution of dark energy density numerically for several forms of scale factor and analytically under some assumptions corresponding to a late epoch of the universe. We discuss some cosmological parameters and fix them using recent observational data, such as those from the Background Imaging of Cosmic Extragalactic Polarization 2 (BICEP2) telescope.
In this paper, we suggest that a toy model of our universe is based on FRW bulk viscous cosmology in presence of modified Chaplygin gas. We obtain modified Friedman equations due to bulk viscosity and Chaplygin gas and calculate time-dependent energy density for the special case of flat space.
We consider noncommutative two-dimensional quantum harmonic oscillators and extend them to the case of twisted algebra. We obtained modified raising and lowering operators. Also we study statistical mechanics and thermodynamics and calculated partition function which yields the free energy of the system.
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