CMB acoustic scale in the entropic-like accelerating universe

Abstract

We consider generalizations of the entropic accelerating universe recently proposed in Ref. [4,5] and show that their background equations can be made equivalent to a model with a dark energy component with constant parameter of state $w_X=-1+2\gamma /3$, where $\gamma$ is related to the coefficients of the new terms in the Friedman equations. After discussing all the Friedman equations for an arbitrary $\gamma$, we show how to recover the standard scalings for dust and radiation. The acoustic scale ${\ell }_A$, related to the peak positions in the pattern of the angular power spectrum of the Cosmic Microwave Background anisotropies, is also computed and yields the stringent bound $|\gamma |\ll 1$. We then argue that future data might be able to distinguish this model from pure $\Lambda$CDM (corresponding to $\gamma =0$).

6 pages, 2 figures. Accepted for publication in Physical Review D

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• Evolution of the universe in entropic cosmologies via different formulations
• Entropic-force dark energy reconsidered
• Non-adiabatic-like accelerated expansion of the late universe in entropic cosmology
• Entropic cosmology in a dissipative universe
• Entropic Force Scenarios and Eternal Inflation
• Noncommutative Geometry Inspired Entropic Inflation
• Cosmological Constraints on Entropic Cosmology with Matter Creation
• Entropic force, running gravitational coupling and future singularities
• Dynamical behavior of the Universe: an entropic force scenario