Cosmic expansion with curved dark energy cosmology: Inevitability of cosmic doomsday

2021 ◽  
pp. 2150048
Author(s):  
Chayanika Rabha ◽  
Sanjeev Kalita
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Spatial Curvature ◽  
Dark Energy Density ◽  
Future Evolution ◽  
Cosmic Expansion ◽  
Energy Models ◽  
Type Ia ◽  
Ia Supernovae ◽  
Dynamical Dark Energy

In this work, we have constructed deceleration–acceleration and future evolution of cosmic expansion with curved dynamical dark energy models. Closed and open spatial curvatures are calculated by assuming that dark energy density does not exceed 85% of the closure density and by obtaining lower bounds on the ratio of dark energy to matter density, in terms of equation of state of dark energy. The range of transition epoch [Formula: see text] realized for spatial curvature [Formula: see text] is consistent with model independent estimations coming from galactic ages, strong lensing, Type Ia supernovae and recent constraints coming from [Formula: see text] measurements in non-flat dynamical dark energy models. Two novel parametrizations of dark energy equation of state namely the logarithmic and oscillatory, which are singularity free at future point [Formula: see text] are used to study the deceleration parameter q(z). Irrespective of spatial curvature, cosmic doomsday has been found inevitable for both the parametrizations. The time evolution of logarithmic parametrization, being reminiscent of a quintom field (canonical[Formula: see text]phantom), is converted into dynamics of a canonical quintessence and a phantom field for the redshift range ([Formula: see text],[Formula: see text]) and ([Formula: see text], [Formula: see text]). It is found that irrespective of spatial curvature, the quintessence component becomes sub-dominant in future giving it’s way to the phantom component.

THE EFFECT OF CURVATURE IN DETERMINING THE PROPERTY OF DARK ENERGY FROM TYPE IA SUPERNOVA WITH A MODEL INDEPENDENT METHOD

2013 ◽  
Vol 22 (06) ◽  
pp. 1350025 ◽  
Author(s):  
XIANGYUN FU ◽  
PUXUN WU ◽  
HONGWEI YU ◽  
BINGJU ZHOU
Keyword(s):  
Dark Energy ◽  
Smoothing Function ◽  
Spatial Curvature ◽  
Apparent Effect ◽  
Cosmic Expansion ◽  
Type Ia ◽  
Model Independent ◽  
Ia Supernovae ◽  
Energy Property ◽  
Cosmic Expansion History

The effect of spatial curvature in reconstructing the cosmic expansion history and the property of dark energy is studied in this paper by smoothing the noise of the Union2.1 Type Ia Supernovae (SNIa) data with a Gaussian smoothing function. We find that the spatial curvature induces an apparent effect in reconstructing the Hubble parameter H(z), the deceleration parameter q(z), and especially on the equation of state w(z) of dark energy. Thus, when one probes the dark energy property, an assumption of a flat universe may induce critical bias and it is imperative to take account of the spatial curvature.

scholarly journals RECONSTRUCTION OF 5D COSMOLOGICAL MODELS FROM RECENT OBSERVATIONS

2007 ◽  
Vol 16 (10) ◽  
pp. 1573-1579
Author(s):  
CHENGWU ZHANG ◽  
LIXIN XU ◽  
YONGLI PING ◽  
HONGYA LIU
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Equation Of State ◽  
Cosmological Solution ◽  
Type Ia Supernovae ◽  
Shift Parameter ◽  
Type Ia ◽  
Ia Supernovae ◽  
Best Fit ◽  
The Universe

We use a parameterized equation of state (EOS) of dark energy to a 5D Ricci-flat cosmological solution and suppose the universe contains two major components: dark matter and dark energy. Using the recent observational datasets: the latest 182 type Ia Supernovae Gold data, the three-year WMAP CMB shift parameter and the SDSS baryon acoustic peak, we obtain the best fit values of the EOS and two major components' evolution. We find that the best fit EOS crosses -1 in the near past where z ≃ 0.07, the present best fit value of wx(0) < -1 and for this model, the universe experiences the acceleration at about z ≃ 0.5.

scholarly journals Constraints on barotropic dark energy models by a new phenomenological q(z) parameterization

2019 ◽  
Vol 79 (11) ◽  
Author(s):  
Jaime Román-Garza ◽  
Tomás Verdugo ◽  
Juan Magaña ◽  
Verónica Motta
Keyword(s):  
Dark Energy ◽  
Joint Analysis ◽  
Effective Equation ◽  
Phantom Divide ◽  
Plane Analysis ◽  
Energy Models ◽  
A Value ◽  
Type Ia ◽  
Ia Supernovae ◽  
The Universe

Abstract In this paper, we propose a new phenomenological two parameter parameterization of q(z) to constrain barotropic dark energy models by considering a spatially flat Universe, neglecting the radiation component, and reconstructing the effective equation of state (EoS). This two free-parameter EoS reconstruction shows a non-monotonic behavior, pointing to a more general fitting for the scalar field models, like thawing and freezing models. We constrain the q(z) free parameters using the observational data of the Hubble parameter obtained from cosmic chronometers, the joint-light-analysis Type Ia Supernovae (SNIa) sample, the Pantheon (SNIa) sample, and a joint analysis from these data. We obtain, for the joint analysis with the Pantheon (SNIa) sample a value of q(z) today, $$q_0=-0.51\begin{array}{c} +0.09 \\ -0.10 \end{array}$$q0=-0.51+0.09-0.10, and a transition redshift, $$z_t=0.65\begin{array}{c} +0.19 \\ -0.17 \end{array}$$zt=0.65+0.19-0.17 (when the Universe change from an decelerated phase to an accelerated one). The effective EoS reconstruction and the $$\omega '$$ω′–$$\omega $$ω plane analysis point towards a transition over the phantom divide, i.e. $$\omega =-1$$ω=-1, which is consistent with a non parametric EoS reconstruction reported by other authors.

GRAVITATIONAL LENSING CONSTRAINT ON THE COSMIC EQUATION OF STATE

2003 ◽  
Vol 12 (05) ◽  
pp. 953-962 ◽  
Author(s):  
DEEPAK JAIN ◽  
ABHA DEV ◽  
N. PANCHAPAKESAN ◽  
S. MAHAJAN ◽  
V. B. BHATIA
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Gravitational Lensing ◽  
Energy Component ◽  
Distance Measurements ◽  
Dark Energy Component ◽  
Highly Sensitive ◽  
Type Ia ◽  
Image Separation ◽  
Ia Supernovae

Recent redshift-distance measurements of Type Ia supernovae (SNe Ia) at cosmological distances suggest that two-third of the energy density of the universe is dominated by dark energy component with an effective negative pressure. This dark energy component is described by the equation of state px= wρx(w ≥ - 1). We use gravitational lensing statistics to constrain the equation of state of this dark energy. We use n(Δθ), the image separation distribution function of lensed quasars, as a tool to probe w. We find that for the observed range of Ωm~ 0.2–0.4, w should lie between -0.8 ≤ w ≤ -0.4 in order to have five lensed quasars in a sample of 867 optical quasars. This limit is highly sensitive to lens and Schechter parameters and the evolution of galaxies.

scholarly journals Analysis off(R)Theory Corresponding to NADE and NHDE

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
M. Sharif ◽  
M. Zubair
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Deceleration Parameter ◽  
Holographic Dark Energy ◽  
Cosmological Parameters ◽  
State Parameter ◽  
Future Evolution ◽  
Energy Models ◽  
Equation Of State Parameter ◽  
Effective Description

We develop the connection off(R)theory with new agegraphic and holographic dark energy models. The functionf(R)is reconstructed regarding thef(R)theory as an effective description for these dark energy models. We show the future evolution offand conclude that these functions represent distinct pictures of cosmological eras. The cosmological parameters such as equation of state parameter, deceleration parameter, statefinder diagnostic, andw−w′analysis are investigated which assure the evolutionary paradigm off.

scholarly journals Testing the isotropy of the Universe with Type Ia supernovae in a model-independent way

2017 ◽  
Vol 474 (3) ◽  
pp. 3516-3522 ◽  
Author(s):  
Yu-Yang Wang ◽  
F Y Wang
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Light Curve ◽  
Type Ia Supernovae ◽  
Anisotropic Universe ◽  
Preferred Direction ◽  
Type Ia ◽  
Model Independent ◽  
Ia Supernovae ◽  
The Universe

Abstract In this paper, we study an anisotropic universe model with Bianchi-I metric using Joint light-curve analysis (JLA) sample of Type Ia supernovae (SNe Ia). Because light-curve parameters of SNe Ia vary with different cosmological models and SNe Ia samples, we fit the SNe Ia light-curve parameters and cosmological parameters simultaneously employing Markov chain Monte Carlo method. Therefore, the results on the amount of deviation from isotropy of the dark energy equation of state (δ), and the level of anisotropy of the large-scale geometry (Σ0) at present, are totally model-independent. The constraints on the skewness and cosmic shear are −0.101 &lt; δ &lt; 0.071 and −0.007 &lt; Σ0 &lt; 0.008. This result is consistent with a standard isotropic universe (δ = Σ0 = 0). However, a moderate level of anisotropy in the geometry of the Universe and the equation of state of dark energy, is allowed. Besides, there is no obvious evidence for a preferred direction of anisotropic axis in this model.

CONSTRAINTS ON VARIABLE CHAPLYGIN GAS MODEL FROM TYPE IA SUPERNOVAE AND BARYON ACOUSTIC OSCILLATIONS

2010 ◽  
Vol 25 (09) ◽  
pp. 737-747 ◽  
Author(s):  
JIANBO LU ◽  
LIXIN XU
Keyword(s):  
Dark Energy ◽  
Chaplygin Gas ◽  
Model Parameters ◽  
Type Ia Supernovae ◽  
Acoustic Oscillations ◽  
Confidence Levels ◽  
Energy Models ◽  
Type Ia ◽  
Baryon Acoustic Oscillations ◽  
Ia Supernovae

We apply the type Ia supernovae union dataset and the baryon acoustic oscillations data at z = 0.2 and z = 0.35 to constrain variable Chaplygin gas (VCG) model as the unification of dark matter and dark energy. It is shown that the confidence levels for VCG model parameters are [Formula: see text]. And it indicates that the values of transition redshift and current deceleration parameter are: [Formula: see text]. In addition, we plot the evolution trajectory of the VCG model in the statefinder parameter r–s plane and show the discrimination between this scenario and other dark energy models.

scholarly journals Update constraints on neutrino mass and mass hierarchy in light of dark energy models

2020 ◽  
Vol 29 (13) ◽  
pp. 2050088
Author(s):  
Zhenjie Liu ◽  
Haitao Miao
Keyword(s):  
Dark Energy ◽  
Neutrino Masses ◽  
Mass Hierarchy ◽  
Acoustic Oscillations ◽  
Energy Models ◽  
Background Data ◽  
Type Ia ◽  
Model Independent ◽  
Degenerate Neutrino ◽  
Ia Supernovae

Combining cosmic microwave (CMB) background data from Planck satellite data, Baryon Acoustic Oscillations (BAO) measurements and Type Ia supernovae (SNe Ia) data, we obtain the bounds on total neutrino masses [Formula: see text] with the approximation of degenerate neutrino masses and for three dark energy models: the cosmological constant ([Formula: see text]CDM) model, a phenomenological emergent dark energy (PEDE) model and a model-independent quintessential parametrization (HBK). The bounds on the sum of neutrino masses [Formula: see text] depend on the dark energy (DE) models. In the HBK model, we confirm the conclusion from some previous work that the quintessence prior of DE tends to tighten the cosmological constraint on [Formula: see text]. On the other hand, the PEDE model leads to larger [Formula: see text] and a nonzero lower bound. Besides, we also explore the correlation between three different neutrino hierarchies and DE models.

scholarly journals SNe Ia as a cosmological probe

2015 ◽  
Vol 24 (14) ◽  
pp. 1530029 ◽  
Author(s):  
Xiangcun Meng ◽  
Yan Gao ◽  
Zhanwen Han
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
High Redshift ◽  
Type Ia Supernovae ◽  
Analysis Techniques ◽  
Type Ia ◽  
History Of ◽  
Acceleration Of The Universe ◽  
Ia Supernovae ◽  
The Universe

Type Ia supernovae (SNe Ia) luminosities can be corrected in order to render them useful as standard candles that are able to probe the expansion history of the universe. This technique was successfully applied to discover the present acceleration of the universe. As the number of SNe Ia observed at high redshift increases and analysis techniques are perfected, people aim to use this technique to probe the equation-of-state of the dark energy (EOSDE). Nevertheless, the nature of SNe Ia progenitors remains controversial and concerns persist about possible evolution effects that may be larger and harder to characterize than the more obvious statistical uncertainties.

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