Observational constraints on modified Chaplygin gas from cosmic growth

Paul, Bikash Chandra; Thakur, P.

doi:10.1088/1475-7516/2013/11/052

Cited by 34 publications

(35 citation statements)

References 80 publications

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“…Contours for χ 2 Σ with the formula (11) in all panels are drawn as blue lines. Other model parameters are fixed and shown in the panels and in table V, they are optimal for the fitting formula (10) (but not optimal for the case (11) These estimates for the MCG model should be compared with similar results for this model in papers [45][46][47]. The authors of Ref.…”

Section: Modified Chaplygin Gasmentioning

confidence: 99%

Observational constraints on cosmological models with Chaplygin gas and quadratic equation of state

Sharov

2016

J. Cosmol. Astropart. Phys.

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1 Tver state university 170002, Sadovyj per. 35, Tver, Russia * Observational manifestations of accelerated expansion of the universe, in particular, recent data for Type Ia supernovae, baryon acoustic oscillations, for the Hubble parameter H(z) and cosmic microwave background constraints are described with different cosmological models. We compare the ΛCDM, the models with generalized and modified Chaplygin gas and the model with quadratic equation of state. For these models we estimate optimal model parameters and their permissible errors with different approaches to calculation of sound horizon scale r s (z d ). Among the considered models the best value of χ 2 is achieved for the model with quadratic equation of state, but it has 2 additional parameters in comparison with the ΛCDM and therefore is not favored by the Akaike information criterion. * Electronic address: german.sharov@mail.ru

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Section: Modified Chaplygin Gasmentioning

confidence: 99%

Observational constraints on cosmological models with Chaplygin gas and quadratic equation of state

Sharov

2016

J. Cosmol. Astropart. Phys.

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“…A compilation of 63 f σ 8 measurements published by various surveys from 2006 to present is shown in Table II along with the corresponding fiducial cosmology assumed in each case. Despite of the existence of such a large sample of published f σ 8 data, most previous analyses [27,31,34,56,[58][59][60][61][62][63][64][65][66][67][68] that use growth data to constrain cosmological models use less than 20 data points which are usually selected from the larger data set of Table II on the basis of subjective criteria that favor more recent data as well as a qualitative minimization of correlations among the selected data points. Indeed, since many of these data points are correlated due to overlap in the galaxy samples used for their derivation, a large covariance matrix should be used for their combined analysis.…”

Section: Introductionmentioning

confidence: 99%

Evolution of the fσ8 tension with the Planck15/ΛCDM determination and implications for modified gravity theories

2018

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We construct an updated extended compilation of distinct (but possibly correlated) f σ8(z) redshift space distortion (RSD) data published between 2006 and 2018. It consists of 63 data points and is significantly larger than previously used similar data sets. After fiducial model correction we obtain the best fit Ω0m − σ8 ΛCDM parameters and show that they are at a 5σ tension with the corresponding Planck15/ΛCDM values. Introducing a nontrivial covariance matrix correlating randomly 20% of the RSD data points has no significant effect on the above tension level. We show that the tension disappears (becomes less than 1σ) when a subsample of the 20 most recently published data is used. A partial cause for this reduced tension is the fact that more recent data tend to probe higher redshifts (with higher errorbars) where there is degeneracy among different models due to matter domination. Allowing for a nontrivial evolution of the effective Newton's constant(ga is a parameter) and fixing a Planck15/ΛCDM background we find ga = −0.91 ± 0.17 from the full f σ8 data set while the 20 earliest and 20 latest data points imply ga = −1.28 +0.28 −0.26 and ga = −0.43 +0.46 −0.41 respectively. Thus, the more recent f σ8 data appear to favor GR in contrast to earlier data. Finally, we show that the parametrization f σ8(z) = λσ8Ω(z) γ /(1 + z) β provides an excellent fit to the solution of the growth equation for both GR (ga = 0) and modified gravity (ga = 0).

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“…Therefore a large number of alternative cosmological models have been proposed. They include modified gravity with f (R) Lagrangian [27,28], theories with scalar fields [29,30], models with nontrivial equations of state [31][32][33][34][35][36][37][38][39], with extra dimensions [40][41][42][43][44][45][46][47] and many others [23][24][25][26].…”

Section: Introductionmentioning

confidence: 99%

Parameters of cosmological models and recent astronomical observations

Sharov

Vorontsova

2014

J. Cosmol. Astropart. Phys.

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1 Tver state university 170002, Sadovyj per. 35, Tver, Russia * For different gravitational models we consider limitations on their parameters coming from recent observational data for type Ia supernovae, baryon acoustic oscillations, and from 34 data points for the Hubble parameter H(z) depending on redshift. We calculate parameters of 3 models describing accelerated expansion of the universe: the ΛCDM model, the model with generalized Chaplygin gas (GCG) and the multidimensional model of I. Pahwa, D. Choudhury and T.R. Seshadri. In particular, for the ΛCDM model 1σ estimates of parameters are: H 0 = 70.262±0.319 km c −1 Mpc −1 , Ω m = 0.276 +0.009 −0.008 , Ω Λ = 0.769±0.029, Ω k = −0.045 ± 0.032. The GCG model under restriction α ≥ 0 is reduced to the ΛCDM model. Predictions of the multidimensional model essentially depend on 3 data points for H(z) with z ≥ 2.3. * Electronic address: german.sharov@mail.ru

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Observational constraints on modified Chaplygin gas from cosmic growth

Cited by 34 publications

References 80 publications

Observational constraints on cosmological models with Chaplygin gas and quadratic equation of state

Observational constraints on cosmological models with Chaplygin gas and quadratic equation of state

Evolution of the fσ8 tension with the Planck15/ΛCDM determination and implications for modified gravity theories

Parameters of cosmological models and recent astronomical observations

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