Dark energy with oscillatory tracking potential: observational constraints and perturbative effects

Abstract

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 α-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 this paper, we study the oscillatory tracker model (OTM), which belongs to the family of α-attractor dark energy models. Using the current observational data sets like cosmic microwave background (CMB), baryon acoustic oscillation, and type 1a supernova data (Pantheon compilation), we constrain the parameters of the model and estimate both the mean and best-fitting values. Although the OTM contains a larger set of parameters than the usual lambda cold dark matter (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 support Hubble parameter value H0 = 67.4  Km s−1 Mpc−1. We study the effect of the OTM on the CMB temperature and polarization power spectra, matter power spectrum and fσ8. 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.