A unique equation of state for the universe evolution from AdS$_5$ space-time

TL;DR

This paper introduces a five-dimensional cosmological model derived from AdS$_5$ space-time that unifies different cosmic expansion phases and relates the universe's matter content to an equation of state similar to the MIT bag model, fitting observational data.

Contribution

It presents a novel five-dimensional cosmological solution with an equation of state analogous to the MIT bag model, connecting extra-dimensional physics with observable universe dynamics.

Findings

Describes radiation-dominated and bounce cosmological models.

Provides a continuous description of cosmic acceleration and deceleration.

Fits observational Hubble parameter data with H_0=72.2 km/s/Mpc.

Abstract

We apply the Induced Matter Model to a five-dimensional metric. For the case with null cosmological constant, we obtain a solution able to describe the radiation-dominated era of the universe. The positive $\Lambda$ case yields a bounce cosmological model. In the negative five-dimensional cosmological constant case, the scale factor is obtained as $a(t)\sim\sqrt[]{\sinh t}$, which is able to describe not only the late-time cosmic acceleration but also the non-accelerated stages of the cosmic expansion in a continuous form. This solution together with the extra-dimensional scale factor solution yields the material content of the model to be remarkably related through an equation of state analogous to the renowned MIT bag model equation of state for quark matter $p=(\rho-4B)/3$. In our case, $\rho=\rho_m+B$, with $\rho_m$ being the energy density of relativistic and non-relativistic matter and $B=\ \Lambda\ /16\pi$ represents the bag energy constant, which plays the role of the dark energy in the four-dimensional universe, with $\Lambda$ being the cosmological constant of the AdS$_5$ space-time. Our model satisfactorily fits the observational data for the low redshift sample of the experimental measurement of the Hubble parameter, which resulted in $H_0=72.2^{+5.3}_{-5.5}$km s$^{-1}$ Mpc$^{-1}$.