Cosmological constraints on the variable modified Chaplygin gas model by using MCMC approach

2015 ◽  
Vol 24 (08) ◽  
pp. 1550059 ◽  
Author(s):  
Jian-bin Chen ◽  
Zhen-qi Liu ◽  
Lili Xing
Keyword(s):  
Apparent Horizon ◽  
Chaplygin Gas ◽  
Modified Chaplygin Gas ◽  
Acoustic Oscillations ◽  
Microwave Background ◽  
Mean Values ◽  
Cosmological Constraints ◽  
Variable Modified Chaplygin Gas ◽  
Type Ia ◽  
Ia Supernovae

We investigate the cosmological constraints on the variable modified Chaplygin gas (VMCG) model from the latest observational data: Union2 dataset of Type Ia supernovae (SNIa), the observational Hubble data (OHD), the baryon acoustic oscillations (BAO) and the cosmic microwave background (CMB) data. By using the Markov chain Monte Carlo (MCMC) method, we obtain the mean values of parameters in the flat model: [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text]. Furthermore, we investigate the thermodynamical properties of VMCG model at apparent horizon, event horizon and particle horizon respectively.

scholarly journals Can f(R) gravity relieve $$H_0$$ and $$\sigma _8$$ tensions?

2021 ◽  
Vol 81 (5) ◽  
Author(s):  
Deng Wang
Keyword(s):  
Cosmic Microwave Background ◽  
Confidence Level ◽  
Cosmological Parameters ◽  
Type Ia Supernovae ◽  
Acoustic Oscillations ◽  
Microwave Background ◽  
Type Ia ◽  
Baryon Acoustic Oscillations ◽  
Ia Supernovae

AbstractTo investigate whether f(R) gravity can relieve current $$H_0$$ H 0 and $$\sigma _8$$ σ 8 tensions, we constrain the Hu-Sawicki f(R) gravity with Planck-2018 cosmic microwave background and redshift space distortions observations. We find that this model fails to relieve both $$H_0$$ H 0 and $$\sigma _8$$ σ 8 tensions, and that its two typical parameters $$\log _{10}f_{R0}$$ log 10 f R 0 and n are insensitive to other cosmological parameters. Combining the cosmic microwave background, baryon acoustic oscillations, Type Ia supernovae, cosmic chronometers with redshift space distortions observations, we give our best constraint $$\log _{10}f_{R0}<-6.75$$ log 10 f R 0 < - 6.75 at the $$2\sigma $$ 2 σ confidence level.

scholarly journals OBSERVATIONAL CONSTRAINTS ON PHANTOM CROSSING DGP GRAVITY

2011 ◽  
Vol 20 (01) ◽  
pp. 1-16 ◽  
Author(s):  
KOICHI HIRANO ◽  
ZEN KOMIYA
Keyword(s):  
Observational Constraints ◽  
Late Time ◽  
Acoustic Oscillations ◽  
Microwave Background ◽  
Phantom Divide ◽  
Phantom Crossing ◽  
Type Ia ◽  
Acceleration Of The Universe ◽  
Ia Supernovae ◽  
Best Fit

We study the observational constraints on the Phantom Crossing DGP model. We demonstrate that the crossing of the phantom divide does not occur within the framework of the original Dvali–Gabadadze–Porrati (DGP) model or the DGP model developed by Dvali and Turner. By extending their model in the framework of an extra dimension scenario, we study a model that realizes crossing of the phantom divide. We investigate the cosmological constraints obtained from the recent observational data of Type Ia supernovae, cosmic microwave background anisotropies, and baryon acoustic oscillations. The best-fit values of the parameters with 1σ (68%) errors for the Phantom Crossing DGP model are [Formula: see text]. We find that the Phantom Crossing DGP model is more compatible with the observations than the original DGP model or the DGP model developed by Dvali and Turner. Our model can realize late-time acceleration of the universe, similar to that of ΛCDM model, without dark energy due to the effect of DGP gravity. In our model, the crossing of the phantom divide occurs at a redshift of z ~ 0.2.

scholarly journals COSMIC CONSTRAINT ON RICCI DARK ENERGY MODEL

2009 ◽  
Vol 24 (17) ◽  
pp. 1355-1360 ◽  
Author(s):  
LIXIN XU ◽  
WENBO LI ◽  
JIANBO LU
Keyword(s):  
Dark Energy ◽  
Dark Energy Model ◽  
Energy Model ◽  
Likelihood Method ◽  
Acoustic Oscillations ◽  
Microwave Background ◽  
Ricci Dark Energy ◽  
Type Ia ◽  
Ia Supernovae ◽  
Best Fit

In this paper, a holographic dark energy model, dubbed Ricci dark energy, is confronted with cosmological observational data from type Ia Supernovae (SN Ia), baryon acoustic oscillations (BAO) and cosmic microwave background (CMB). By using maximum likelihood method, we found that Ricci dark energy model is a viable candidate of dark energy model with the best fit parameters: Ωm0 = 0.34 ± 0.04, α = 0.38 ± 0.03 with 1σ error. Here, α is a dimensionless parameter related to Ricci dark energy ρR and Ricci scalar R, i.e. ρR ∝ αR.

scholarly journals Study of some parameters of modified Chaplygin gas in Galileon gravity theory from observational perspective

2014 ◽  
Vol 92 (12) ◽  
pp. 1667-1675 ◽  
Author(s):  
Chayan Ranjit ◽  
Prabir Rudra ◽  
Ujjal Debnath
Keyword(s):  
Chaplygin Gas ◽  
Cosmic Acceleration ◽  
Joint Analysis ◽  
Type Ia Supernovae ◽  
Distance Modulus ◽  
Modified Chaplygin Gas ◽  
Data Set ◽  
Type Ia ◽  
Ia Supernovae ◽  
Best Fit

We have assumed the Friedmann–Robertson–Walker model of the universe in Galileon gravity, which is filled with dark matter and modified Chaplygin gas (MCG) type dark energy. We present the Hubble parameter in terms of some unknown parameters and observational parameters with the redshift z. Some cosmological parameters are reconstructed and plots are generated to study the nature of the model and its viability. It is seen that the model is perfectly consistent with the present cosmic acceleration. From observed Hubble data (OHD) set or Stern data set of 12 points, we have obtained the bounds of the arbitrary parameters (A, B) and (A, C) by minimizing the χ2 test. Next because of joint analysis of OHD + baryonic acoustic oscillation (BAO) and OHD+BAO+CMB observations, we have also obtained the best fit values and the bounds of the parameters (A, B) and (A, C) by fixing some other parameters. The best-fit values and bounds of the parameters are obtained with 66%, 90%, and 99% confidence levels for OHD, OHD+BAO, and OHD+BAO+CMB joint analysis. Next we have also taken type Ia supernovae data set (union2 data set with 557 data points). The distance modulus μ(z) against redshift z for our theoretical MCG model in Galileon gravity have been tested for the best fit values of the parameters and the observed type Ia supernovae union2 data sample and from this, we have concluded that our model is in agreement with the union2 sample data.

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.

COSMOLOGICAL DISTANCE MEASURE CONSTRAINTS ON THE DECELERATION PARAMETER

2009 ◽  
Vol 18 (09) ◽  
pp. 1381-1393 ◽  
Author(s):  
LIXIN XU ◽  
JIANBO LU ◽  
CHENGWU ZHANG
Keyword(s):  
Deceleration Parameter ◽  
Distance Measure ◽  
High Redshift ◽  
Acoustic Oscillations ◽  
Microwave Background ◽  
Cosmological Distance ◽  
Type Ia ◽  
Hubble Parameters ◽  
Ia Supernovae ◽  
Parameter Values

Constraints on a parametrized deceleration parameter, q(a) = q0+ q1(1 - a), are investigated using cosmological observations of type Ia supernovae (SN Ia), baryon acoustic oscillations (BAOs) and cosmic microwave background (CMB) and observational Hubble data (OHD) which correspond to the cosmological distance measure. When a high redshift dataset of CMB is added in the SN + BAO + OHD case, a stronger constraint is obtained than for the lower redshift case, SN + BAO + OHD. The evolutions of the deceleration and Hubble parameters with respect to redshift z are reconstructed from cosmic observations. With cosmic observations as constraints, it is found that a smaller current deceleration parameter and a larger transition redshift are obtained in the SN + BAO + OHD case than in the SN + BAO + OHD + CMB case. In the SN + BAO + OHD + CMB case, slightly larger Hubble parameter values will be obtained than in the SN + BAO + OHD case.

scholarly journals Cosmological models based on relativity with a privileged frame

2020 ◽  
Vol 29 (06) ◽  
pp. 2050038 ◽  
Author(s):  
Georgy I. Burde
Keyword(s):  
Cosmological Model ◽  
Deceleration Parameter ◽  
Lorentz Invariance ◽  
Local Symmetry ◽  
Cosmological Models ◽  
Acoustic Oscillations ◽  
Microwave Background ◽  
Type Ia ◽  
Frw Cosmological Model ◽  
Ia Supernovae

Cosmological models, stemming from the extension of the “special relativity (SR) with a privileged frame” to general relativity (GR), are developed and fitted to the observational data. The framework termed “SR with a privileged frame” incorporates the privileged frame into SR while retaining the fundamental spacetime symmetry which, in the standard SR, manifests itself as Lorentz invariance. The correspondingly modified GR, like the standard GR, is based on the equivalence principle but with the properly modified spacetime local symmetry in which an invariant combination differs from the Minkowski interval of the standard SR. Applying the modified GR to cosmology yields the luminosity distance — redshift relation corrected such that the observed deceleration parameter can be negative as it is obtained from the data for Type Ia supernovae. Thus, the observed negative values of the deceleration parameter can be explained within the matter-dominated Friedman–Robertson–Walker (FRW) cosmological model of the universe without introducing the dark energy. A number of other observations, such as Baryon Acoustic Oscillations and Cosmic Microwave Background, also can be well fit to the cosmological model arising from the GR based on the SR with a privileged frame.

scholarly journals Bayesian comparison of interacting modified holographic Ricci dark energy scenarios

2021 ◽  
Vol 81 (1) ◽  
Author(s):  
Antonella Cid ◽  
Carlos Rodriguez-Benites ◽  
Mauricio Cataldo ◽  
Gonzalo Casanova
Keyword(s):  
Dark Energy ◽  
Hubble Constant ◽  
Joint Analysis ◽  
Acoustic Oscillations ◽  
Microwave Background ◽  
Ricci Dark Energy ◽  
Type Ia ◽  
Cosmological Data ◽  
Ia Supernovae ◽  
Local Value

AbstractWe perform a Bayesian model selection analysis for interacting scenarios of dark matter and modified holographic Ricci dark energy (MHRDE) with linear interacting terms. We use a combination of some of the latest cosmological data such as type Ia supernovae, cosmic chronometers, the local value of the Hubble constant, baryon acoustic oscillations measurements and cosmic microwave background through the angular scale of the sound horizon at last scattering. We find moderate/strong evidence against all the MHRDE interacting scenarios studied with respect to $$\Lambda $$ Λ CDM when the full joint analysis is considered.

scholarly journals Constraining the Parameters of Modified Chaplygin Gas in Einstein-Aether Gravity

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Ujjal Debnath
Keyword(s):  
Chaplygin Gas ◽  
Joint Analysis ◽  
Distance Modulus ◽  
Modified Chaplygin Gas ◽  
Unknown Parameters ◽  
Data Set ◽  
Type Ia ◽  
Data Points ◽  
Ia Supernovae ◽  
Best Fit

We have assumed FRW model of the universe in Einstein-Aether gravity filled with dark matter and modified Chaplygin gas (MCG) type dark energy. We present the Hubble parameter in terms of some unknown parameters and observational parameters with the redshiftz. From observed Hubble data (OHD) set (12 points), we have obtained the bounds of the arbitrary parameters(A,B)of MCG by minimizing theχ2test. Next due to joint analysis of BAO and CMB observations, we have also obtained the best fit values and the bounds of the parameters(A,B)by fixing some other parameters. We have also taken type Ia supernovae data set (union 2 data set with 557 data points). Next due to joint analysis with SNe, we have obtained the best fit values of parameters. The best fit values and bounds of the parameters are obtained by 66%, 90%, and 99% confidence levels for OHD, OHD + BAO, OHD + BAO + CMB, and OHD + BAO + CMB + SNe joint analysis. The distance modulusμzagainst redshiftzfor our theoretical MCG model in Einstein-Aether gravity has been tested for the best fit values of the parameters and the observed SNe Ia union2 data sample.

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