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Register a new userPhenomenological model explaining Hubble Tension origin
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Added by
G. S. Bisnovatyi-Kogan
Publication date
2020
fields
Physics
and research's language is
English
Authors
G.S. Bisnovatyi-Kogan
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One of the problem revealed recently in cosmology is a so-called Hubble tension (HT), which is the difference between values of the present Hubble constant, measured by observation of the universe at redshift $z lesssim 1$, and by observations of a distant universe with CMB fluctuations originated at $z sim 1100$. In this paper we suggest, that this discrepancy may be explained by deviation of the cosmological expansion from a standard Lambda-CDM %simple Friedman model of a flat universe, during the period after recombination at $z lesssim 1100$, due to action of additional variable component of a dark energy of different origin.. We suppose, that a dark matter (DM) has a common origin with a variable component of a dark energy (DEV). DE presently may have two components, one of which is the Einstein constant $Lambda$, and another, smaller component DEV ($Lambda_V$) comes from the remnants of a scalar fields responsible for inflation. Due to common origin and interconnections the densities of DEV and DM are supposed to be connected, and remain almost constant during, at least, the time after recombination, when we may approximate $rho_{DM}=alpha rho_{DEV}$. This part of the dark energy in not connected with the cosmological constant $Lambda$, but is defined by existence of scalar fields with a variable density. Taking into account the influence of DEV on the universe expansion we find the value of $alpha$ which could remove the HT problem. In order to maintain the almost constant DEV/DM energy density ratio during the time interval at $z<1100$, we suggest an existence of a wide mass DM particle distribution.
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We investigate a generalized form of the phenomenologically emergent dark energy model, known as generalized emergent dark energy (GEDE), introduced by Li and Shafieloo [Astrophys. J. {bf 902}, 58 (2020)] in light of a series of cosmological probes and considering the evolution of the model at the level of linear perturbations. This model introduces a free parameter $Delta$ that can discriminate between the $Lambda$CDM (corresponds to $Delta=0$) or the phenomenologically emergent dark energy (PEDE) (corresponds to $Delta=1$) models, allowing us to determine which model is preferred most by the fit of the observational datasets. We find evidence in favor of the GEDE model for Planck alone and in combination with R19, while the Bayesian model comparison is inconclusive when Supernovae Type Ia or BAO data are included. In particular, we find that $Lambda$CDM model is disfavored at more than $2sigma$ CL for most of the observational datasets considered in this work and PEDE is in agreement with Planck 2018+BAO+R19 combination within $1sigma$ CL.
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