Dark energy equation of state parameter and its variation at low redshifts

TL;DR

This study constrains dark energy models at low redshifts using supernova, BAO, and Hubble data, finding strong limits on its density variation and highlighting tensions in varying models.

Contribution

It provides combined observational constraints on dark energy's equation of state and its evolution at low redshifts, comparing constant and varying models.

Findings

Strong limits on dark energy density variation

Tension between supernova data and other measurements for varying models

Combined data constrains dark energy parameters effectively

Abstract

In this paper, we constrain dark energy models using a compendium of observations at low redshifts. We consider the dark energy as a barotropic fluid, with the equation of state a constant as well the case where dark energy equation of state is a function of time. The observations considered here are Supernova Type Ia data, Baryonic Acoustic Oscillation data and Hubble parameter measurements. We compare constraints obtained from these data and also do a combined analysis. The combined observational constraints put strong limits on variation of dark energy energy density with redshift. For varying dark energy models, the range of parameters preferred by the supernova type Ia data is in tension with the other low redshift distance measurements.