scholarly journals Dynamical Stability and Geometrical Diagnostic of the Power Law K-Essence Dark Energy Model with Interaction

Universe ◽  
2020 ◽  
Vol 6 (12) ◽  
pp. 244
Author(s):  
Bo-Hai Chen ◽  
Ya-Bo Wu ◽  
Dong-Fang Xu ◽  
Wei Dong ◽  
Nan Zhang
Keyword(s):  
Dark Energy ◽  
Power Law ◽  
Critical Points ◽  
Coupling Parameter ◽  
Cosmological Evolution ◽  
Potential Parameter ◽  
Dynamical Process ◽  
Accelerating Expansion ◽  
Evolutionary Trajectories ◽  
Autonomous Dynamical System

We investigate the cosmological evolution of the power law k-essence dark energy (DE) model with interaction in FRWL spacetime with the Lagrangian that contains a kinetic function F(X)=−X+X. Concretely, the cosmological evolution in this model are discussed by the autonomous dynamical system and its critical points, together with the corresponding cosmological quantities, such as Ωϕ, wϕ, cs2, and q, are calculated at each critical point. The evolutionary trajectories are drawn in order to show the dynamical process on the phases plan around the critical points. The result that we obtained indicates that there are four dynamical attractors, and all of them correspond to an accelerating expansion of universe for certain potential parameter and coupling parameter. Besides that, the geometrical diagnostic by the statefinder hierarchy S3(1) and S4(1) of this scalar field model are numerically obtained by the phase components, as an extended null diagnostic for the cosmological constant. This diagnostic shows that both the potential parameter λ and interaction parameter α play important roles in the evolution of the statefinder hierarchy.

scholarly journals Power-law entropy-corrected new agegraphic dark energy in Hořava–Lifshitz cosmology

2012 ◽  
Vol 90 (5) ◽  
pp. 473-479 ◽  
Author(s):  
K. Karami ◽  
A. Sheykhi ◽  
M. Jamil ◽  
R. Myrzakulov ◽  
S. Ghaffari ◽  
...  
Keyword(s):  
Dark Energy ◽  
Power Law ◽  
Dark Energy Model ◽  
Coupling Parameter ◽  
State Parameter ◽  
Density Parameter ◽  
Agegraphic Dark Energy ◽  
New Agegraphic Dark Energy ◽  
Corrected Entropy ◽  
Interacting Dark Energy Model

We investigate the new agegraphic dark energy (NADE) model with power-law corrected entropy in the framework of Hořava–Lifshitz cosmology. For a nonflat universe containing the interacting power-law entropy-corrected NADE with dark matter, we obtain the differential equation of the evolution of the density parameter as well as the deceleration parameter. To study parametric behavior, we use an interesting form of state parameter as a function of redshift ωΛ(z) = ω0 + ω1z. We find that phantom crossing occurs for the state parameter for a nonzero coupling parameter, thus supporting the interacting dark energy model.

BOUNDS ON f(G) GRAVITY FROM ENERGY CONDITIONS

2010 ◽  
Vol 25 (27) ◽  
pp. 2325-2332 ◽  
Author(s):  
PUXUN WU ◽  
HONGWEI YU
Keyword(s):  
General Relativity ◽  
Dark Energy ◽  
Energy Density ◽  
Modified Gravity ◽  
Energy Conditions ◽  
Model Parameters ◽  
Effective Energy ◽  
Raychaudhuri Equation ◽  
Accelerating Expansion

The f(G) gravity is a theory to modify the general relativity and it can explain the present cosmic accelerating expansion without the need of dark energy. In this paper the f(G) gravity is tested with the energy conditions. Using the Raychaudhuri equation along with the requirement that the gravity is attractive in the FRW background, we obtain the bounds on f(G) from the SEC and NEC. These bounds can also be found directly from the SEC and NEC within the general relativity context by the transformations: ρ → ρm + ρE and p → pm + pE, where ρE and pE are the effective energy density and pressure in the modified gravity. With these transformations, the constraints on f(G) from the WEC and DEC are obtained. Finally, we examine two concrete examples with WEC and obtain the allowed region of model parameters.

scholarly journals Precise astronomical flux calibration and its impact on studying the nature of the dark energy

2015 ◽  
Vol 30 (40) ◽  
pp. 1530030 ◽  
Author(s):  
Christopher W. Stubbs ◽  
Yorke J. Brown
Keyword(s):  
Dark Energy ◽  
Survey Methodology ◽  
Atmospheric Transmission ◽  
Dwarf Stars ◽  
White Dwarf Stars ◽  
Accelerating Expansion ◽  
Systematic Uncertainties ◽  
Type Ia ◽  
Ia Supernovae ◽  
Flux Calibration

Measurements of the luminosity of Type Ia supernovae versus redshift provided the original evidence for the accelerating expansion of the Universe and the existence of dark energy. Despite substantial improvements in survey methodology, systematic uncertainty in flux calibration dominates the error budget for this technique, exceeding both statistics and other systematic uncertainties. Consequently, any further collection of Type Ia supernova data will fail to refine the constraints on the nature of dark energy unless we also improve the state of the art in astronomical flux calibration to the order of 1%. We describe how these systematic errors arise from calibration of instrumental sensitivity, atmospheric transmission and Galactic extinction, and discuss ongoing efforts to meet the 1% precision challenge using white dwarf stars as celestial standards, exquisitely calibrated detectors as fundamental metrologic standards, and real-time atmospheric monitoring.

Testing anisotropy and comparison of various supernova data constraints on dark energy model

2019 ◽  
Vol 34 (34) ◽  
pp. 1950276 ◽  
Author(s):  
H. Hossienkhani ◽  
H. Yousefi ◽  
N. Azimi
Keyword(s):  
Dark Energy ◽  
Dark Energy Model ◽  
Cosmological Parameters ◽  
Acoustic Oscillation ◽  
Maximum Likelihood Analysis ◽  
Accelerating Expansion ◽  
Combining Data ◽  
Likelihood Analysis ◽  
Data Constraints ◽  
The Universe

We study the possibly existing anisotropy in the accelerating expansion Universe with various supernovae data, the baryon acoustic oscillation and the observational Hubble data. We present combined results from these probes, deriving constraints on the equation of state (EoS), [Formula: see text], of dark energy (DE) and its energy density in the Universe. We fit the cosmological parameters simultaneously employing the maximum likelihood analysis. By combining data and considering anisotropy effects, we find that the EoS of DE are [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] within [Formula: see text] confidence level. Finally, introducing an anisotropy appears to improve the fit to observations with respect to that provided by an isotropic [Formula: see text]CDM model.

scholarly journals Unveiling the Evolution of Type I AGNs in the IR (15μm) — As Seen by ISO in the ELAIS-S1 Region

2002 ◽  
Vol 184 ◽  
pp. 167-172
Author(s):  
Israel Matute ◽  
Fabio La Franca ◽  
Carlotta Gruppioni ◽  
Francesca Pozzi ◽  
Carlo Lari
Keyword(s):  
Power Law ◽  
Luminosity Function ◽  
Evolution Model ◽  
Cosmological Evolution ◽  
Type I ◽  
Infrared Background ◽  
Power Law Function ◽  
Cosmic Infrared Background ◽  
Luminosity Evolution

AbstractWe present the first estimate of the evolution of type 1 AGNs in the IR (15 μm) obtained from the ELAIS survey in the S1 region. We find that the luminosity function (LF) of Type 1 AGNs at 15μm is fairly well represented by a double power-law function with a bright slope of 2.9 and a faint slope of 1.1. There is evidence for significant cosmological evolution according to a pure luminosity evolution model L15(z)α(l+z)k, with in a (Ωm,ΩΛ)=(1.0,0.0) cosmology. This evolution is similar to what is observed at other wavebands. From the luminosity function and its evolution, we estimate a contribution of ~ 2% from Type 1 AGN to the total Cosmic Infrared Background (CIRB) at 15 μm.

scholarly journals The cosmological behavior and the statefinder diagnosis for the New Tsallis agegraphic dark energy

2020 ◽  
Vol 35 (38) ◽  
pp. 2050318
Author(s):  
Umesh Kumar Sharma ◽  
Shikha Srivastava
Keyword(s):  
Dark Energy ◽  
Dynamical Analysis ◽  
Current Phase ◽  
Statefinder Parameters ◽  
Frw Universe ◽  
Eos Parameter ◽  
Agegraphic Dark Energy ◽  
Evolutionary Trajectories ◽  
The Universe ◽  
Friedmann Robertson Walker

In this work, we have considered the recently proposed new Tsallis agegraphic dark energy (NTADE) model [Mod. Phys. Lett. A 34, 1950086 (2019)] within the framework of a flat Friedmann–Robertson–Walker (FRW) Universe by taking various values of the parameter [Formula: see text]. The NTADE model shows the current phase transition of the Universe from decelerated to accelerated phase. The NTADE equation of state (EoS) parameter shows a rich behavior as it can be quintessence-like or phantom-like depending on the value of [Formula: see text]. For discriminating the NTADE model from [Formula: see text]CDM, we have plotted the statefinder parameters [Formula: see text], [Formula: see text] and [Formula: see text], [Formula: see text] pair. The NTADE model shows distinct evolutionary trajectories of their evolution in ([Formula: see text]) and ([Formula: see text]) plane. An analysis using the snap parameter and the [Formula: see text] pair dynamical analysis have also been performed.

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