Generalized models of unification of dark matter and dark energy

TL;DR

This paper introduces a generalized unification model for dark matter and dark energy based on a variable sound speed, encompassing Chaplygin gas models, and constrains it using observational Hubble data.

Contribution

It proposes a new generalized model where the sound speed depends on the equation of state parameter, unifying dark matter and dark energy, with scalar field representation and observational constraints.

Findings

Model includes generalized Chaplygin gas as a special case.

Scalar field potential can be expressed in closed form in some cases.

Model parameters are constrained using observational Hubble data.

Abstract

A model of unification of dark matter and dark energy based on the modeling of the speed of sound as a function of the parameter of the equation of state is introduced. It is found that the model in which the speed of sound depends on the power of the parameter of the equation of state, $c_s^2=\alpha (-w)^{\gamma}$, contains the generalized Chaplygin gas models as its subclass. An effective scalar field description of the model is obtained in a parametric form which in some cases can be translated into a closed form solution for the scalar field potential. A constraint on model parameters is obtained using the observational data on the Hubble parameter at different redshifts.