Abstract
In this work we examine the recently proposed phenomenological emergent dark energy (PEDE) model by [1], using the latest observational data in both expansion and perturbation levels. Applying the statistical Bayesian evidence as well as the AIC and BIC information criteria, we compare the PEDE model with the concordance Lambda CDM model in both flat and non-flat universes. We combine the observational datasets as (i) expansion data (except CMB), (ii) expansion data (including CMB) and (iii) expansion data jointed to the growth rate dataset. Our statistical results show that the flat- Lambda CDM model is still the best model. In the case of expansion data (including CMB), we observe that the flat- PEDE model is well consistent with observations as well as the concordance Lambda CDM universe. While in the cases of (i) and (iii), the PEDE models in both of the flat and non-flat geometries are not favored. In particular, we see that in the perturbation level the PEDE model can not fit the observations as equally as standard Lambda CDM cosmology. As the ability of the model, we show that the PEDE models can alleviate the tension of Hubble constant value appearing between the local observations and Planck inferred estimation in standard cosmology.
Highlights
Fine-tuning (i.e., the fact that the value of this cosmological constant inferred from observations is extremely small compared with the energy scales of high energy physics (Planck, grand unified theory, strong and even electroweak scales) and cosmic coincidence issues [10,11,12,13]
We present the results of our analysis for non-flat phenomenological emergent dark energy (PEDE) and CDM model models, respectively, in Tables 4 and 5
Same as the flat geometry, in the case of non-flat PEDE model, we obtain the larger value of H0 compared to non-flat CDM model
Summary
In order to overcome or at least alleviate the above problems, different kinds of dynamical dark energy (DE) models have been proposed. Quintessence [21], ghost [22,23,24], holographic [25], k-essence [26], phantom [27], tachyon [28], dilaton [29], quintom [30] and dynamical vacuum energy [31] are examples of such dynamical DE models Many of these models have been compared with various observational data obtained from different cosmic surveys. In [1], authors by assuming hard cut priors from local measurement of the Hubble constant ,compared the model with combined sets of observations at both low and high redshifts, include SnIa data, BAO data and CMB measurement Their investigation showed that the PEDE model statistically is better than the CDM cosmology.
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