scholarly journals Model‐independent Constraints on Dark Energy Density from Flux‐averaging Analysis of Type Ia Supernova Data

2004 ◽  
Vol 606 (2) ◽  
pp. 654-663 ◽  
Author(s):  
Yun Wang ◽  
Pia Mukherjee
Keyword(s):  
Dark Energy ◽  
Energy Density ◽  
Dark Energy Density ◽  
Type Ia Supernova ◽  
Type Ia ◽  
Model Independent ◽  
Averaging Analysis

scholarly journals RECONSTRUCTING DARK ENERGY

2006 ◽  
Vol 15 (12) ◽  
pp. 2105-2132 ◽  
Author(s):  
VARUN SAHNI ◽  
ALEXEI STAROBINSKY
Keyword(s):  
Dark Energy ◽  
Energy Density ◽  
Current Data ◽  
Effective Equation ◽  
Dark Energy Density ◽  
Future Directions ◽  
Reconstruction Methods ◽  
History Of ◽  
Model Independent ◽  
Constant Energy Density

This review summarizes recent attempts to reconstruct the expansion history of the universe and to probe the nature of dark energy. Reconstruction methods can be broadly classified into parametric and non-parametric approaches. It is encouraging that, even with the limited observational data currently available, different approaches give consistent results for the reconstruction of the Hubble parameter H(z) and the effective equation of state w(z) of dark energy. Model independent reconstruction using current data allows for modest evolution of dark energy density with redshift. However, a cosmological constant (= dark energy with a constant energy density) remains an excellent fit to the data. Some pitfalls to be guarded against during cosmological reconstruction are summarized and future directions for the model independent reconstruction of dark energy are explored.

scholarly journals Dark Energy Density in Brane World

2005 ◽  
Vol 22 (4) ◽  
pp. 816-819 ◽  
Author(s):  
Wen Hai-Bao ◽  
Huang Xin-Bing
Keyword(s):  
Dark Energy ◽  
Energy Density ◽  
Brane World ◽  
Dark Energy Density

scholarly journals Limits on decaying dark energy density models from the CMB temperature–redshift relation

2010 ◽  
Vol 43 (4) ◽  
pp. 1083-1093 ◽  
Author(s):  
Philippe Jetzer ◽  
Denis Puy ◽  
Monique Signore ◽  
Crescenzo Tortora
Keyword(s):  
Dark Energy ◽  
Energy Density ◽  
Dark Energy Density ◽  
Cmb Temperature

Ghost dark energy in Rastall theory

2021 ◽  
pp. 2150090
Author(s):  
E. E. Kangal ◽  
M. Salti ◽  
O. Aydogdu
Keyword(s):  
Dark Energy ◽  
Energy Density ◽  
Text Analysis ◽  
Functional Form ◽  
Expansion Rate ◽  
Dark Energy Density ◽  
Cosmic Expansion ◽  
Astrophysical Data ◽  
Ghost Dark Energy ◽  
History Of

Making use of the generalized form of the Ghost dark energy density, which has the functional form [Formula: see text] where [Formula: see text] represents the Hubble expanding rate, the present accelerated enlargement behavior of the cosmos is investigated from the Rastall theory perspective. After finding a relation for the Hubble cosmic expansion rate, we consider recent cosmology-independent measurements calculated for the expansion history of the cosmos to fit the model via the [Formula: see text]-analysis. Moreover, we discuss the cosmographic properties of the model with the help of some cosmological quantities. We show that our model is stable and consistent with the recent astrophysical data. Also, for our model, we investigate cosmological interpretations of thermodynamics.

scholarly journals Cosmological Constant from the Entropy Balance Condition

2018 ◽  
Vol 2018 ◽  
pp. 1-5
Author(s):  
Merab Gogberashvili
Keyword(s):  
Dark Energy ◽  
Energy Density ◽  
Apparent Horizon ◽  
Critical Density ◽  
Zero Energy ◽  
Dark Energy Density ◽  
Event Horizons ◽  
Balance Condition ◽  
Quantum Particles ◽  
Hubble Horizon

In the action formalism variations of metric tensors usually are limited by the Hubble horizon. On the contrary, variations of quantum fields should be extended up to the event horizon, which is the real boundary of the spacetime. As a result the entanglement energy of quantum particles across the apparent horizon is missed in the cosmological equations written for the Hubble volume. We identify this missing boundary term with the dark energy density and express it (using the zero energy assumption for the finite universe) as the critical density multiplied by the ratio of the Hubble and event horizons radii.

FRW viscous modified cosmic Chaplygin gas cosmology in the presence of cosmological constant

2019 ◽  
Vol 16 (09) ◽  
pp. 1950141 ◽  
Author(s):  
G. S. Khadekar ◽  
Aina Gupta ◽  
Kalpana Pande
Keyword(s):  
Dark Energy ◽  
Energy Density ◽  
Cosmological Constant ◽  
Chaplygin Gas ◽  
Frw Universe ◽  
Dark Energy Density ◽  
Linear Combinations ◽  
Linear Differential ◽  
The Stability ◽  
Cardassian Universe

In this paper, we study viscous Modified Cosmic Chaplygin Gas (MCCG) in the presence of cosmological constant in flat FRW universe. We assume that bulk viscosity [Formula: see text] and cosmological constant [Formula: see text] are the linear combinations of two terms, one is constant and other is a function of dark energy density [Formula: see text]. In this framework, we solve the non-linear differential equation analytically and numerically and obtain time dependent dark energy density. We also consider two separate cases of early and late universe and discussed the evolution of dark energy density. We investigate the effect of viscosity and cosmological constant to the evolution of universe and discuss the stability of the model by square of speed of sound. Finally, we compare our model with Cardassian universe.

Holographic dark energy in a vector field cosmology

2015 ◽  
Vol 12 (10) ◽  
pp. 1550119 ◽  
Author(s):  
S. Davood Sadatian
Keyword(s):  
Dark Energy ◽  
Vector Field ◽  
Equation Of State ◽  
Energy Density ◽  
Holographic Dark Energy ◽  
Lorentz Invariance ◽  
Holographic Model ◽  
Dark Energy Density ◽  
Invariance Violation ◽  
Lorentz Invariance Violation

We obtain interacting holographic dark energy density in the framework of vector field cosmology (LIV). We consider possible modification of equation of state for the holographic energy density in lorentz invariance violation cosmology. In this case we select Jeans length as the IR cut-off in the holographic model. Then we consider the interaction between holographic energy densities ρΛ and ρm in this framework.

scholarly journals SUPERNOVA Ia AND GALAXY CLUSTER GAS MASS FRACTION CONSTRAINTS ON DARK ENERGY

2006 ◽  
Vol 21 (29) ◽  
pp. 2197-2204 ◽  
Author(s):  
KYLE M. WILSON ◽  
GANG CHEN ◽  
BHARAT RATRA
Keyword(s):  
Dark Energy ◽  
Energy Density ◽  
Cosmological Constant ◽  
Mass Fraction ◽  
Galaxy Cluster ◽  
Apparent Magnitude ◽  
Model Parameters ◽  
Dark Energy Density ◽  
Energy Models ◽  
Fraction Versus

We use the Riess et al. (2004)1 supernova Ia apparent magnitude versus redshift data and the Allen et al. (2004)2 galaxy cluster gas mass fraction versus redshift data to constrain dark energy models. These data provide complementary constraints that when combined together significantly restrict model parameters and favor slowly-evolving dark energy density models, close to the Einstein cosmological constant limit of dark energy.

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