scholarly journals Non-linear interacting cosmological models after Planck 2018 legacy release and the H0 tension

2020 ◽  
Vol 493 (3) ◽  
pp. 3114-3131 ◽  
Author(s):  
Supriya Pan ◽  
Weiqiang Yang ◽  
Andronikos Paliathanasis
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Observational Data ◽  
Energy Equation ◽  
Hubble Space Telescope ◽  
Hubble Constant ◽  
Acoustic Oscillations ◽  
Coincidence Problem ◽  
Linear Interaction ◽  
Non Linear

ABSTRACT Interacting dark energy models are widely renowned for giving an explanation to the cosmic coincidence problem as well as several observational issues. According to the recent observational data, and so far we are concerned with the literature, the choice of the interaction function between dark matter and dark energy is always questionable since there is no such underlying theory that could derive it. Thus, in this work we have raised this issue by proposing two new non-linear interaction functions and constrain them using cosmic microwave background (CMB) from Planck 2018, baryon acoustic oscillations (BAOs), dark energy survey and a measurement of the Hubble constant H0 from Hubble Space Telescope (HST) 2019. The dark energy equation of state is considered to be constant throughout the work and the geometry of the universe is assumed to be homogeneous and isotropic with zero spatial curvature. Our analyses report that a non-zero interaction is always allowed by the observational data and the dark energy equation of state is bent towards the phantom regime. In particular, when H0 from HST is added to Planck 2018+BAO, we find an evidence for a non-zero coupling at more than 2σ confidence level. Our analyses also report that for both the models, H0 is close to its local measurements and thus alleviating the H0 tension. In particular, one of the interacting models perfectly solves the H0 tension.

scholarly journals Observational Constraints on Dynamical Dark Energy with Pivoting Redshift

Universe ◽  
2019 ◽  
Vol 5 (11) ◽  
pp. 219 ◽  
Author(s):  
Weiqiang Yang ◽  
Supriya Pan ◽  
Eleonora Di Valentino ◽  
Emmanuel N. Saridakis
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Free Parameter ◽  
Energy Equation ◽  
Hubble Constant ◽  
Mean Value ◽  
Observational Constraints ◽  
Acoustic Oscillations ◽  
Light Curve Analysis ◽  
Full Data

We investigate the generalized Chevallier–Polarski–Linder (CPL) parametrization, which contains the pivoting redshift z p as an extra free parameter, in order to examine whether the evolution of the dark energy equation of state can be better described by a different parametrization. We use various data combinations from cosmic microwave background (CMB), baryon acoustic oscillations (BAO), redshift space distortion (RSD), weak lensing (WL), joint light curve analysis (JLA), and cosmic chronometers (CC), and we include a Gaussian prior on the Hubble constant value, in order to extract the observational constraints on various quantities. For the case of free z p we find that for all data combinations it always remains unconstrained, and there is a degeneracy with the value of the dark energy equation of state w 0 p at z p . For the case where z p is fixed to specific values, and for the full data combination, we find that with increasing z p the mean value of w 0 p slowly moves into the phantom regime, however the cosmological constant is always allowed within 1 σ confidence-level. In fact, the significant effect is that with increasing z p , the correlations between w 0 p and w a (the free parameter of the dark energy equation of state quantifying its evolution with redshift), change from negative to positive, with the case z p = 0 . 35 corresponding to no correlation. The fact that the two parameters describing the dark energy equation of state are uncorrelated for z p = 0 . 35 justifies why a non-zero pivoting redshift needs to be taken into account.

scholarly journals MEASURING NEUTRINO MASSES AND DARK ENERGY

2008 ◽  
Vol 23 (34) ◽  
pp. 2881-2895
Author(s):  
HUITZU TU
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Neutrino Mass ◽  
Energy Equation ◽  
Mass Scale ◽  
Neutrino Masses ◽  
Acoustic Oscillations ◽  
Distance Measurements ◽  
The Galaxy ◽  
Absolute Neutrino Mass

We review some recent efforts in determining the absolute neutrino mass scale in cosmology. We illustrate in particular how distance measurements such as the baryon acoustic oscillations and the galaxy weak lensing can break the degeneracy between the neutrino mass and dark energy equation of state parameters.

CONSTRAINTS ON THE DARK ENERGY EQUATION OF STATE IN PRESENCE OF A VARYING FINE STRUCTURE CONSTANT

2010 ◽  
Vol 19 (04) ◽  
pp. 507-512 ◽  
Author(s):  
E. MENEGONI ◽  
S. PANDOLFI ◽  
S. GALLI ◽  
M. LATTANZI ◽  
A. MELCHIORRI
Keyword(s):  
Fine Structure ◽  
Dark Energy ◽  
Equation Of State ◽  
Cosmological Constant ◽  
Energy Equation ◽  
Structure Constant ◽  
Hubble Constant ◽  
Fine Structure Constant ◽  
Cosmological Constraints ◽  
Energy Models

We discuss the cosmological constraints on the dark energy equation of state in the presence of primordial variations in the fine structure constant. We find that the constraints from CMB data alone on w and the Hubble constant are much weaker when variations in the fine structure constant are permitted. Vice versa, constraints on the fine structure constant are relaxed by more than 50% when dark energy models different from a cosmological constant are considered.

scholarly journals Clustering and halo abundances in early dark energy cosmological models

2021 ◽  
Vol 504 (1) ◽  
pp. 769-781
Author(s):  
Anatoly Klypin ◽  
Vivian Poulin ◽  
Francisco Prada ◽  
Joel Primack ◽  
Marc Kamionkowski ◽  
...  
Keyword(s):  
Dark Energy ◽  
Cold Dark Matter ◽  
Power Spectra ◽  
Hubble Constant ◽  
Cosmological Models ◽  
Acoustic Oscillations ◽  
Microwave Background ◽  
Linear Evolution ◽  
James Webb Space Telescope ◽  
Non Linear

ABSTRACT Cold Dark Matter with cosmological constant (ΛCDM) cosmological models with early dark energy (EDE) have been proposed to resolve tensions between the Hubble constant $H_0=100\, h$ km ṡ−1Ṁpc−1 measured locally, giving h ≈ 0.73, and H0 deduced from Planck cosmic microwave background (CMB) and other early-Universe measurements plus ΛCDM, giving h ≈ 0.67. EDE models do this by adding a scalar field that temporarily adds dark energy equal to about 10 per cent of the cosmological energy density at the end of the radiation-dominated era at redshift z ∼ 3500. Here, we compare linear and non-linear predictions of a Planck-normalized ΛCDM model including EDE giving h = 0.728 with those of standard Planck-normalized ΛCDM with h = 0.678. We find that non-linear evolution reduces the differences between power spectra of fluctuations at low redshifts. As a result, at z = 0 the halo mass functions on galactic scales are nearly the same, with differences only 1–2 per cent. However, the differences dramatically increase at high redshifts. The EDE model predicts 50 per cent more massive clusters at z = 1 and twice more galaxy-mass haloes at z = 4. Even greater increases in abundances of galaxy-mass haloes at higher redshifts may make it easier to reionize the universe with EDE. Predicted galaxy abundances and clustering will soon be tested by the James Webb Space Telescope (JWST) observations. Positions of baryonic acoustic oscillations (BAOs) and correlation functions differ by about 2 per cent between the models – an effect that is not washed out by non-linearities. Both standard ΛCDM and the EDE model studied here agree well with presently available acoustic-scale observations, but the Dark Energy Spectroscopic Instrument and Euclid measurements will provide stringent new tests.

scholarly journals Dynamical dark energy after Planck CMB final release and H0 tension

2020 ◽  
Author(s):  
Weiqiang Yang ◽  
Eleonora Di Valentino ◽  
Supriya Pan ◽  
Yabo Wu ◽  
Jianbo Lu
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Hubble Space Telescope ◽  
Acoustic Oscillations ◽  
Energy Models ◽  
Bayesian Evidence ◽  
Local Measurements ◽  
Evidence Analysis ◽  
Baryon Acoustic Oscillations ◽  
Dynamical Dark Energy

Abstract In this article we compare a variety of well known dynamical dark energy models using the cosmic microwave background measurements from the 2018 Planck legacy and 2015 Planck data releases, the baryon acoustic oscillations measurements and the local measurements of H0 obtained by the SH0ES (Supernovae, H0, for the Equation of State of Dark energy) collaboration analysing the Hubble Space Telescope data. We discuss the alleviation of H0 tension, that is obtained at the price of a phantom-like dark energy equation of state. We perform a Bayesian evidence analysis to quantify the improvement of the fit, finding that all the dark energy models considered in this work are preferred against the ΛCDM scenario. Finally, among all the possibilities analyzed, the CPL model is the best one in fitting the data and solving the H0 tension at the same time. However, unfortunately, this dynamical dark energy solution is not supported by the baryon acoustic oscillations (BAO) data, and the tension is restored when BAO data are included for all the models.

scholarly journals Late Time Attractors of Some Varying Chaplygin Gas Cosmological Models

Symmetry ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 769
Author(s):  
Martiros Khurshudyan ◽  
Ratbay Myrzakulov
Keyword(s):  
Dark Energy ◽  
Gravitational Interaction ◽  
Chaplygin Gas ◽  
Cosmological Models ◽  
Late Time ◽  
Time Behavior ◽  
Coincidence Problem ◽  
Energy Models ◽  
Non Linear ◽  
Bayesian Machine Learning

The goal of this paper is to study new cosmological models where the dark energy is a varying Chaplygin gas. This specific dark energy model with non-linear EoS had been often discussed in modern cosmology. Contrary to previous studies, we consider new forms of non-linear non-gravitational interaction between dark matter and assumed dark energy models. We applied the phase space analysis allowing understanding the late time behavior of the models. It allows demonstrating that considered non-gravitational interactions can solve the cosmological coincidence problem. On the other hand, we applied Bayesian Machine Learning technique to learn the constraints on the free parameters. In this way, we gained a better understanding of the models providing a hint which of them can be ruled out. Moreover, the learning based on the simulated expansion rate data shows that the models cannot solve the H0 tension problem.

scholarly journals Nonparametric reconstruction of the dark energy equation of state from diverse data sets

2011 ◽  
Vol 84 (8) ◽  
Author(s):  
Tracy Holsclaw ◽  
Ujjaini Alam ◽  
Bruno Sansó ◽  
Herbie Lee ◽  
Katrin Heitmann ◽  
...  
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Energy Equation ◽  
Data Sets ◽  
Diverse Data
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