Dark energy with oscillatory tracking potential: Observational Constraints and Perturbative effects

TL;DR

This paper investigates an oscillatory tracker dark energy model within the $ ext{α}$-attractor framework, constraining its parameters with observational data and analyzing its effects on cosmological spectra, showing close agreement with LCDM but notable differences.

Contribution

It introduces and constrains the oscillatory tracker model using current observational data, highlighting its similarities and differences with the standard LCDM model.

Findings

Model parameters are consistent within 1σ with LCDM.

Supports Hubble constant $H_0 = 67.4$ km/s/Mpc.

Shows noticeable differences in cosmological spectra from LCDM.

Abstract

The cosmological models exhibiting tracker properties have great significance in the context of dark energy as they can reach the present value of dark energy density from a wide range of initial conditions, thereby alleviating both the fine-tuning and the cosmic coincidence problem. The $\alpha$-attractors, which are originally discussed in the context of inflation, can exhibit the properties of dark energy as they can behave like cosmological trackers at early times and show the late time behaviour of a cosmological constant. In the present paper, we study the Oscillatory Tracker Model (OTM), which belongs to the family of $\alpha$-attractor dark energy models. Using the current observational data sets like Cosmic Microwave Background (CMB), Baryon Acoustic Oscillation (BAO) and type 1a supernova data (Pantheon compilation), we constrain the parameters of the model and estimate both the mean and best-fit values. Although the oscillatory tracker model contains a larger set of parameters than the usual LCDM model, the common set of parameters of both agree within $1\, \sigma$ error limits. Our observations using both high redshift and low redshift data supports Hubble parameter value $H_0 = 67.4$ Kms$^{-1}$Mpc$^{-1}$. We study the effect of the OTM on the CMB temperature and polarization power spectra, matter power spectrum and $f \sigma_8$. Our analysis of the CMB power spectrum and matter power spectrum suggests that the oscillatory tracker dark energy model has noticeable differences from usual LCDM predictions. Yet, in most cases, the agreement is very close.