Constraining decaying dark energy density models with the CMB temperature-redshift relation

TL;DR

This paper investigates variable dark energy models with density scaling as (1+z)^m, analyzing their effects on cosmic evolution and the CMB temperature-redshift relation, and constrains them using current measurements.

Contribution

It introduces and constrains a variable dark energy model affecting matter and radiation, using CMB temperature data up to redshift 3.

Findings

Model is indistinguishable from a cosmological constant within current uncertainties.

Future CMB temperature measurements at high redshift can tighten bounds on dark energy properties.

Current data cannot distinguish the variable dark energy model from the standard cosmological constant.

Abstract

We discuss the thermodynamic and dynamical properties of a variable dark energy model with density scaling as $\rho_x \propto (1+z)^{m}$, z being the redshift. These models lead to the creation/disruption of matter and radiation, which affect the cosmic evolution of both matter and radiation components in the Universe. In particular, we have studied the temperature-redshift relation of radiation, which has been constrained using a recent collection of cosmic microwave background (CMB) temperature measurements up to $z \sim 3$. We find that, within the uncertainties, the model is indistinguishable from a cosmological constant which does not exchange any particles with other components. Future observations, in particular measurements of CMB temperature at large redshift, will allow to give firmer bounds on the effective equation of state parameter $w_{eff}$ for such types of dark energy models.