Probing phenomenological emergent dark energy model in a Bianchi type-I spacetime with the recent observational data

Abstract

In this work, we investigate the recently introduced phenomenological emergent dark energy (PEDE) model and the anisotropic extension of PEDE ( A PEDE) via Bianchi type-I spacetime metric with the latest observational data involving both low and high redshift datasets as, Hubble, Cosmic Microwave Background (CMB), Baryon Acoustic Oscillations (BAO) and Pantheon. We perform Bayesian inference analysis to carry out a detailed comparison of these models with the standard Λ CDM and anisotropic Λ CDM ( A Λ CDM) models. The 68% confidence limit (CL) constraints on Hubble constant with joint data combination for both PEDE and A PEDE models yield H 0 = 70 . 8 ± 0 . 5 km s − 1 Mpc − 1 , consistent with the local value H 0 = 69 . 8 ± 0 . 8 km s − 1 Mpc − 1 based on a calibration of the Tip of the Red Giant Branch applied to supernovae Type Ia. In addition, this value provides ∼ 2 . 1 σ tension in comparison with the local measurement value 74 . 03 ± 1 . 42 km s − 1 Mpc − 1 from Hubble Space Telescope observations of Cepheids in the Large Magellanic Cloud. The phantom like behaviour of dark energy in PEDE and A PEDE models lead to an early redshift transition in comparison with Λ CDM and A Λ CDM models. Further, we observe that the upper bound on the expansion anisotropy parameter Ω σ 0 for A PEDE at 95% CL is approximately of the order 1 0 − 18 with all data combinations, unable to make any relevant change in the CMB quadrupole problem. Moreover, we find that the expansion anisotropy for A PEDE ( A Λ CDM) model does not alter the conclusions for PEDE ( Λ CDM) model. The statistical results for both PEDE and A PEDE models in comparison with the base Λ CDM show a good fit with the data combination of Hubble+CMB, while the addition of BAO or Pantheon with other data combinations lead to a very strong evidence against the PEDE models.