scholarly journals Marginalized Fisher forecast for Horndeski dark energy models

2017 ◽  
Vol 26 (07) ◽  
pp. 1750070 ◽  
Author(s):  
Jason S.-Y. Leung ◽  
Zhiqi Huang
Keyword(s):  
Dark Energy ◽  
Effective Field Theory ◽  
Energy Equation ◽  
Cosmological Parameters ◽  
Effective Field ◽  
Nuisance Parameters ◽  
Galaxy Surveys ◽  
Energy Parameters ◽  
Energy Models ◽  
State Formula

We use effective field theory (EFT) formalism to forecast the constraint on Horndeski class of dark energy models with future supernova and galaxy surveys. Previously, Gleyzes et al. computed unmarginalized constraints (68% CL error [Formula: see text]–[Formula: see text]) on EFT dark energy parameters by fixing all other parameters. We extend the previous work by allowing all cosmological parameters and nuisance parameters to vary and marginalize over them. We find that (i) the constraints on EFT dark energy parameters are typically worsen by a factor of few after marginalization, and (ii) the constraint on the dark energy equation-of-state [Formula: see text] is not significantly affected by the inclusion of EFT dark energy parameters.

scholarly journals Unveiling cosmography from the dark energy equation of state

2019 ◽  
Vol 28 (12) ◽  
pp. 1950154 ◽  
Author(s):  
Celia Escamilla-Rivera ◽  
Salvatore Capozziello
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Energy Equation ◽  
Cosmological Parameters ◽  
Cosmic Acceleration ◽  
Type Ia ◽  
State Formula ◽  
Cosmological Tests ◽  
Supernovae Type Ia ◽  
Straightforward Approach

Constraining the dark energy equation of state, [Formula: see text], is one of the main issues of current and future cosmological surveys. In practice, this requires making assumptions about the evolution of [Formula: see text] with redshift [Formula: see text], which can be manifested in a choice of a specific parametric form where the number of cosmological parameters play an important role in the observed cosmic acceleration. Since any attempt to constrain the EoS requires some prior fixing in one form or the other, settling a method to constrain cosmological parameters is of great importance. In this paper, we provide a straightforward approach to show how cosmological tests can be improved via a parametric methodology based on cosmography. Using Supernovae Type IA samplers, we show how by performing a statistical analysis of a specific dark energy parametrization can give directly the cosmographic parameters values.

scholarly journals Using a multi-messenger and multi-wavelength observational strategy to probe the nature of dark energy through direct measurements of cosmic expansion history

2021 ◽  
Vol 2021 (12) ◽  
pp. 042
Author(s):  
Jing-Zhao Qi ◽  
Shang-Jie Jin ◽  
Xi-Long Fan ◽  
Jing-Fei Zhang ◽  
Xin Zhang
Keyword(s):  
Dark Energy ◽  
Cosmological Parameters ◽  
Data Sets ◽  
Energy Parameters ◽  
Energy Models ◽  
Redshift Drift ◽  
Multi Wavelength ◽  
Weak Constraints ◽  
Almost All ◽  
Observational Strategy

Abstract In the near future, the redshift drift observations in optical and radio bands will provide precise measurements on H(z) covering the redshift ranges of 2<z<5 and 0<z<0.3. In addition, gravitational wave (GW) standard siren observations could make measurements on the dipole anisotropy of luminosity distance, which will also provide the H(z) measurements in the redshift range of 0<z<3. In this work, we propose a multi-messenger and multi-wavelength observational strategy to measure H(z) based on the three next-generation projects, E-ELT, SKA, and DECIGO, and we wish to see whether the future H(z) measurements could provide tight constraints on dark-energy parameters. The dark energy models we consider include ΛCDM, wCDM, CPL, HDE, and IΛCDM models. It is found that E-ELT, SKA1, and DECIGO are highly complementary in constraining dark energy models. Although any one of these three data sets can only give rather weak constraints on each model we consider, the combination of them could significantly break the parameter degeneracies and give much tighter constraints on almost all the cosmological parameters. Moreover, we find that the combination of E-ELT, SKA1, DECIGO, and CMB could further improve the constraints on dark energy parameters, e.g., σ(w 0)=0.024 and σ(w a)=0.17 in the CPL model, which means that these three promising probes will play a key role in helping reveal the nature of dark energy.

scholarly journals Neutrino Dispersion Relations from a Dark Energy Model

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Emilio Ciuffoli ◽  
Jarah Evslin ◽  
Jie Liu ◽  
Xinmin Zhang
Keyword(s):  
Dark Energy ◽  
Scalar Field ◽  
Effective Field Theory ◽  
Lorentz Violation ◽  
Effective Field ◽  
Dispersion Relations ◽  
Interstellar Space ◽  
Neutrino Sector ◽  
Energy Models ◽  
The Earth

We consider a model in which the neutrino is kinetically coupled to a scalar field and study its implications for environmentally dependent neutrino velocities. Following the usual effective field theory logic, this coupling is expected to arise in neutrino dark energy models. It leads to a Lorentz violation in the neutrino sector. The coupling of the scalar field to the stress tensor of the Earth yields terrestrial neutrino dispersion relations distinct from those in interstellar space.

scholarly journals Physical Acceptability of the Renyi, Tsallis and Sharma-Mittal Holographic Dark Energy Models in the f(T,B) Gravity under Hubble’s Cutoff

Universe ◽  
2021 ◽  
Vol 7 (3) ◽  
pp. 67
Author(s):  
Salim Harun Shekh ◽  
Pedro H. R. S. Moraes ◽  
Pradyumn Kumar Sahoo
Keyword(s):  
Dark Energy ◽  
Holographic Dark Energy ◽  
Cosmological Parameters ◽  
Field Equations ◽  
Eos Parameter ◽  
Two Fluids ◽  
Gravitational Field Equations ◽  
Energy Models ◽  
Different Types ◽  
The Universe

In the present article, we investigate the physical acceptability of the spatially homogeneous and isotropic Friedmann–Lemâitre–Robertson–Walker line element filled with two fluids, with the first being pressureless matter and the second being different types of holographic dark energy. This geometric and material content is considered within the gravitational field equations of the f(T,B) (where T is the torsion scalar and the B is the boundary term) gravity in Hubble’s cut-off. The cosmological parameters, such as the Equation of State (EoS) parameter, during the cosmic evolution, are calculated. The models are stable throughout the universe expansion. The region in which the model is presented is dependent on the real parameter δ of holographic dark energies. For all δ≥4.5, the models vary from ΛCDM era to the quintessence era.

Cosmological implications of dark energy models in modified gravity

2018 ◽  
Vol 15 (03) ◽  
pp. 1850034 ◽  
Author(s):  
Nadeem Azhar ◽  
Abdul Jawad ◽  
Sarfraz Ahmad ◽  
Iftikhar Ahmed
Keyword(s):  
Dark Energy ◽  
Modified Gravity ◽  
Cold Dark Matter ◽  
Cosmological Parameters ◽  
Accelerated Expansion ◽  
Pilgrim Dark Energy ◽  
Energy Models ◽  
Expansion Of The Universe ◽  
Qcd Ghost Dark Energy ◽  
Chern Simons

We discuss the interacting modified QCD ghost dark energy and generalized ghost pilgrim dark energy with cold dark matter in the framework of dynamical Chern–Simons modified gravity. We investigate the cosmological parameters such as Hubble parameter, deceleration parameter and equation of state. We also discuss the physical significance of various cosmological planes like [Formula: see text] and statefinders. It is found that the results of cosmological parameters as well as planes explain the accelerated expansion of the Universe and are compatible with observational data.

Analysis of entropy corrected holographic and new agegraphic dark energy models in generalized Rastall gravity

2020 ◽  
Vol 35 (28) ◽  
pp. 2050175
Author(s):  
Sayani Maity ◽  
Mahasweta Biswas ◽  
Ujjal Debnath
Keyword(s):  
Dark Energy ◽  
Cosmological Parameters ◽  
State Parameter ◽  
Graphical Analysis ◽  
Future Singularity ◽  
Agegraphic Dark Energy ◽  
New Agegraphic Dark Energy ◽  
Energy Models ◽  
Dark Energy Component ◽  
The Stability

This work deals with two fluid system in the framework of generalized Rastall gravity theory. One component represents dark energy whereas the other is dark matter. For the dark energy component, entropy corrected holographic and entropy corrected new agegraphic dark energy models in power-law and logarithmic versions are taken into account. For this study, we assume two classes of scale factors in which one corresponds to the future singularity and another corresponds to the initial singularity. For each of the entropy corrected dark energy models, the cosmological parameters such as Hubble parameter, deceleration parameter and equation of state parameter are calculated and their implications are established. Furthermore, to describe the stability analysis of the models, the behaviors of the squared speed of sound are analyzed graphically for each of these models. From the graphical analysis of [Formula: see text] plane, the thawing or freezing regions of all the models are determined.

scholarly journals Effective field theory of dark energy: A review

2020 ◽  
Vol 857 ◽  
pp. 1-63 ◽  
Author(s):  
Noemi Frusciante ◽  
Louis Perenon
Keyword(s):  
Field Theory ◽  
Dark Energy ◽  
Effective Field Theory ◽  
Effective Field

scholarly journals NONPARAMETRIC DETERMINATION OF REDSHIFT EVOLUTION INDEX OF DARK ENERGY

2007 ◽  
Vol 22 (21) ◽  
pp. 1569-1580 ◽  
Author(s):  
HOURI ZIAEEPOUR
Keyword(s):  
Dark Energy ◽  
Cosmological Constant ◽  
Cosmological Parameters ◽  
Positive Energy ◽  
Fundamental Constants ◽  
Geometrical Properties ◽  
Precise Data ◽  
Energy Models ◽  
Scaling Models

We propose a nonparametric method to determine the sign of γ — the redshift evolution index of dark energy. This is important for distinguishing between positive energy models, a cosmological constant, and what is generally called ghost models. Our method is based on geometrical properties and is more tolerant to uncertainties of other cosmological parameters than fitting methods in what concerns the sign of γ. The same parametrization can also be used for determining γ and its redshift dependence by fitting. We apply this method to SNLS supernovae and to gold sample of re-analyzed supernovae data from Riess et al. Both datasets show strong indication of a negative γ. If this result is confirmed by more extended and precise data, many of the dark energy models, including simple cosmological constant, standard quintessence models without interaction between quintessence scalar field(s) and matter, and scaling models are ruled out. We have also applied this method to Gurzadyan–Xue models with varying fundamental constants to demonstrate the possibility of using it to test other cosmologies.

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