scholarly journals Cosmological models of generalized ghost pilgrim dark energy (GGPDE) in the gravitation theory of Saez–Ballester

2021 ◽  
Author(s):  
Priyanka Garg ◽  
Archana Dixit ◽  
Anirudh Pradhan
Keyword(s):  
Dark Energy ◽  
Cosmological Parameters ◽  
Acoustic Oscillation ◽  
Type I ◽  
Microwave Background ◽  
Light Curve Analysis ◽  
Pilgrim Dark Energy ◽  
Type Ia ◽  
State Formula ◽  
Quintessence Field

In this paper, we study the mechanism of the cosmic model in the presence of generalized ghost pilgrim dark energy (GGPDE) and matter in locally rotationally symmetric (LRS) Bianchi type-I space-time by the utilization of new holographic DE in Saez–Ballester theory. Here, we discuss all the data for three scenarios, the first is supernovae type-Ia union data, the second is SN Ia data in combination with baryon acoustic oscillation and cosmic microwave background observations and the third is a combination with observational Hubble data and joint light-curve analysis observations. From this, we get a model of our universe, where transit state exists from deceleration to acceleration phase. Here, we have observed that the results yielded by cosmological parameters like [Formula: see text] (energy density), equation of state [Formula: see text], squared speed of sound [Formula: see text] and [Formula: see text]–[Formula: see text] are compatible with the recent observations. The [Formula: see text]–[Formula: see text] trajectories lie in both thawing and freezing regions and the correspondence of the quintessence field with GGPDE is also discussed. Some physical aspects of the GGPDE models are mainly highlighted.

scholarly journals Redshift parametrizations of dark energy and observational constraint on their parameters: Galileon gravity as background

2015 ◽  
Vol 30 (31) ◽  
pp. 1550151 ◽  
Author(s):  
Prabir Rudra ◽  
Chayan Ranjit ◽  
Sujata Kundu
Keyword(s):  
Dark Energy ◽  
Data Analysis ◽  
Theoretical Models ◽  
Acoustic Oscillation ◽  
Model Parameters ◽  
Distance Modulus ◽  
Microwave Background ◽  
Frw Universe ◽  
Type Ia ◽  
Best Fit

In this work, Friedmann–Robertson–Walker (FRW) universe filled with dark matter (DM) (perfect fluid with negligible pressure) along with dark energy (DE) in the background of Galileon gravity is considered. Four DE models with different equation of state (EoS) parametrizations have been employed namely, linear, Chevallier–Polarski–Lindler (CPL), Jassal–Bagla–Padmanabhan (JBP) and logarithmic parametrizations. From Stern, Stern+Baryonic Acoustic Oscillation (BAO) and Stern+BAO+Cosmic Microwave Background (CMB) joint data analysis, we have obtained the bounds of the arbitrary parameters [Formula: see text] and [Formula: see text] by minimizing the [Formula: see text] test. The best fit values and bounds of the parameters are obtained at 66%, 90% and 99% confidence levels which are shown by closed confidence contours in the figures. For the logarithmic model unbounded confidence contours are obtained and hence the model parameters could not be finitely constrained. The distance modulus [Formula: see text](z) against redshift [Formula: see text] has also been plotted for our predicted theoretical models for the best fit values of the parameters and compared with the observed Union2 data sample and SNe Type Ia 292 data and we have shown that our predicted theoretical models permits the observational datasets. From the data fitting it is seen that at lower redshifts [Formula: see text] the SNe Type Ia 292 data gives a better fit with our theoretical models compared to the Union2 data sample. So, from the data analysis, SNe Type Ia 292 data is the more favored data sample over its counterpart given the present choice of free parameters. From the study, it is also seen that the logarithmic parametrization model is less supported by the observational data. Finally, we have generated the plot for the deceleration parameter against the redshift parameter for all the theoretical models and compared the results with the work of Farooq et al., (2013).

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.

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.

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.

Probing the anisotropy effects on the CPL parametrizations from light-curve SNIa, BAO and OHD datasets

2019 ◽  
Vol 16 (11) ◽  
pp. 1950177 ◽  
Author(s):  
H. Hossienkhani ◽  
N. Azimi ◽  
Z. Zarei
Keyword(s):  
Light Curve ◽  
Observational Data ◽  
Cosmological Parameters ◽  
Estimation Method ◽  
Likelihood Estimation ◽  
Anisotropic Universe ◽  
Type I ◽  
Acoustic Oscillations ◽  
Type Ia ◽  
Best Fit

Recent observers have shown that an anisotropy cosmic expansion may exist. In this work, we study the effects of low anisotropy with Bianchi type I model using the current observational data, which includes the supernova Legacy Survey (SNLS) sample of 238 SN events ([Formula: see text]) and 1048 Pantheon sample confirmed type Ia supernova (SNIa) covering the redshift range [Formula: see text]. Assuming an anisotropic universe, we use the two parametrizations of the dark energy equation-of-state, such as the [Formula: see text] (PA) and [Formula: see text] (PB), and then we fit the SNIa light-curve parameters and free cosmological parameters, simultaneously employing maximum likelihood estimation method. When combining the Baryon Acoustic Oscillations (BAO) and the observational Hubble data (OHD) measurements with the SNLS SN sample, we find [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text] for the PA model and [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text] for the PB model. When combining also Pantheon data, we obtain [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text] for the PA model and [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text] for the PB model. The analysis shows that by considering the anisotropy effects, it leads to more best-fit parameters in [Formula: see text]CDM model with the current observational data.

scholarly journals THE EFFECT OF DIFFERENT OBSERVATIONAL DATA IN CONSTRAINING COSMOLOGICAL PARAMETERS

2012 ◽  
Vol 10 ◽  
pp. 85-94 ◽  
Author(s):  
YUNGUI GONG ◽  
QING GAO ◽  
ZONG-HONG ZHU
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Observational Data ◽  
Cosmological Parameters ◽  
State Parameter ◽  
Wilkinson Microwave Anisotropy Probe ◽  
Model Parameters ◽  
Type Ia Supernova ◽  
Equation Of State Parameter ◽  
Type Ia

We use the SNLS3 compilation of 472 type Ia supernova data, the baryon acoustic oscillation measurement of distance, and the cosmic microwave background radiation data from the seven year Wilkinson Microwave Anisotropy Probe to study the effect of their different combinations on the fittings of cosmological parameters. Neither BAO nor WMAP7 data alone gives good constraint on the equation of state parameter of dark energy, but both WMAP7 data and BAO data help type Ia supernova data break the degeneracies among the model parameters, hence tighten the constraint on the variation of equation of state parameter wa, and WMAP7 data does the job a little better. Although BAO and WMAP7 data provide reasonably good constraints on Ωm and Ωk, it is not able to constrain the dynamics of dark energy, we need SNe Ia data to probe the property of dark energy, especially the variation of the equation of state parameter of dark energy. For the SNLS SNe Ia data, the nuisance parameters α and β are consistent for all different combinations of the above data. Their impacts on the fittings of cosmological parameters are minimal. ΛCDM model is consistent with current observational data.

scholarly journals A divergence-free parametrization of deceleration parameter for scalar field dark energy

2016 ◽  
Vol 25 (03) ◽  
pp. 1650032 ◽  
Author(s):  
Abdulla Al Mamon ◽  
Sudipta Das
Keyword(s):  
Dark Energy ◽  
Deceleration Parameter ◽  
Acoustic Oscillations ◽  
Microwave Background ◽  
Frw Universe ◽  
Potential Term ◽  
Type Ia ◽  
De Formula ◽  
Divergence Free ◽  
Baryonic Acoustic Oscillations

In this paper, we have considered a spatially flat FRW universe filled with pressureless matter and dark energy (DE). We have considered a phenomenological parametrization of the deceleration parameter [Formula: see text] and from this, we have reconstructed the equation-of-state (EoS) for DE [Formula: see text]. This divergence-free parametrization of the deceleration parameter is inspired from one of the most popular parametrization of the DE EoS given by Barboza and Alcaniz [see E. M. Barboza and J. S. Alcaniz, Phys. Lett. B 666 (2008) 415]. Using the combination of datasets (Type Ia Supernova (SN Ia) + Hubble + baryonic acoustic oscillations/cosmic microwave background (BAO/CMB)), we have constrained the transition redshift [Formula: see text] (at which the universe switches from a decelerating to an accelerating phase) and have found the best fit value of [Formula: see text]. We have also compared the reconstructed results of [Formula: see text] and [Formula: see text] and have found that the results are compatible with a [Formula: see text]CDM universe if we consider SN Ia + Hubble data, but inclusion of BAO/CMB data makes [Formula: see text] and [Formula: see text] incompatible with [Formula: see text]CDM model. The potential term for the present toy model is found to be functionally similar to a Higgs potential.

scholarly journals First cosmology results using Type IA supernovae from the dark energy survey: effects of chromatic corrections to supernova photometry on measurements of cosmological parameters

2019 ◽  
Vol 485 (4) ◽  
pp. 5329-5344 ◽  
Author(s):  
J Lasker ◽  
R Kessler ◽  
D Scolnic ◽  
D Brout ◽  
D L Burke ◽  
...  
Keyword(s):  
Dark Energy ◽  
Cosmological Parameters ◽  
Critical Density ◽  
Transmission Function ◽  
Type Ia Supernovae ◽  
Distance Modulus ◽  
Dark Energy Survey ◽  
Type Ia ◽  
Ia Supernovae ◽  
Energy Survey

Abstract Calibration uncertainties have been the leading systematic uncertainty in recent analyses using Type Ia supernovae (SNe Ia) to measure cosmological parameters. To improve the calibration, we present the application of spectral energy distribution-dependent ‘chromatic corrections’ to the SN light-curve photometry from the Dark Energy Survey (DES). These corrections depend on the combined atmospheric and instrumental transmission function for each exposure, and they affect photometry at the 0.01 mag (1 per cent) level, comparable to systematic uncertainties in calibration and photometry. Fitting our combined DES and low-z SN Ia sample with baryon acoustic oscillation (BAO) and cosmic microwave background (CMB) priors for the cosmological parameters Ωm (the fraction of the critical density of the universe comprised of matter) and w (the dark energy equation of state parameter), we compare those parameters before and after applying the corrections. We find the change in w and Ωm due to not including chromatic corrections is −0.002 and 0.000, respectively, for the DES-SN3YR sample with BAO and CMB priors, consistent with a larger DES-SN3YR-like simulation, which has a w-change of 0.0005 with an uncertainty of 0.008 and an Ωm change of 0.000 with an uncertainty of 0.002. However, when considering samples on individual CCDs we find large redshift-dependent biases (∼0.02 in distance modulus) for SN distances.

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