scholarly journals Low-redshift constraints on covariant canonical Gauge theory of gravity

2021 ◽  
Vol 81 (2) ◽  
Author(s):  
David Benisty ◽  
David Vasak ◽  
Johannes Kirsch ◽  
Jürgen Struckmeier
Keyword(s):  
Deformation Parameter ◽  
Data Sets ◽  
Acoustic Oscillations ◽  
Spatial Curvature ◽  
Stress Energy ◽  
Type Ia ◽  
Ia Supernovae ◽  
Gauge Gravity ◽  
Gauge Theory Of Gravity ◽  
Combined Data

AbstractConstraints on the Covariant Canonical Gauge Gravity (CCGG) theory from low-redshift cosmology are studied. The formulation extends Einstein’s theory of General Relativity (GR) by a quadratic Riemann–Cartan term in the Lagrangian, controlled by a “deformation” parameter. In the Friedman universe this leads to an additional geometrical stress energy and promotes, due to the necessary presence of torsion, the cosmological constant to a time-dependent function. The MCMC analysis of the combined data sets of Type Ia Supernovae, Cosmic Chronometers and Baryon Acoustic Oscillations yields a fit that is well comparable with the $$\Lambda $$ Λ CDM results. The modifications implied in the CCGG approach turn out to be subdominant in the low-redshift cosmology. However, a non-zero spatial curvature and deformation parameter are shown to be consistent with observations.

scholarly journals Testing the consistency between cosmological data: the impact of spatial curvature and the dark energy EoS

2021 ◽  
Vol 2021 (11) ◽  
pp. 060
Author(s):  
Javier E. Gonzalez ◽  
Micol Benetti ◽  
Rodrigo von Marttens ◽  
Jailson Alcaniz
Keyword(s):  
Dark Energy ◽  
Joint Analysis ◽  
Data Sets ◽  
Acoustic Oscillations ◽  
Spatial Curvature ◽  
Eos Parameter ◽  
Flat Universe ◽  
Type Ia ◽  
Cosmological Data ◽  
The Impact

Abstract The results of joint analyses of available cosmological data have motivated an important debate about a possible detection of a non-zero spatial curvature. If confirmed, such a result would imply a change in our present understanding of cosmic evolution with important theoretical and observational consequences. In this paper we discuss the legitimacy of carrying out joint analyses with the currently available data sets and explore their implications for a non-flat universe and extensions of the standard cosmological model. We use a robust tension estimator to perform a quantitative analysis of the physical consistency between the latest data of Cosmic Microwave Background, type Ia supernovae, Baryonic Acoustic Oscillations and Cosmic Chronometers. We consider the flat and non-flat cases of the ΛCDM cosmology and of two dark energy models with a constant and varying dark energy EoS parameter. The present study allows us to better understand if possible inconsistencies between these data sets are significant enough to make the results of their joint analyses misleading, as well as the actual dependence of such results with the spatial curvature and dark energy parameterizations. According to our results, we conclude that a joint analysis in the context of a non-flat universe including the CMB data is only possible if the CMB Lens is taken into account, otherwise, it potentially leads to misleading conclusions.

scholarly journals Dynamical spatial curvature as a fit to Type Ia supernovae

2019 ◽  
Vol 28 (11) ◽  
pp. 1950143
Author(s):  
Célia Desgrange ◽  
Asta Heinesen ◽  
Thomas Buchert
Keyword(s):  
Broad Class ◽  
Information Criterion ◽  
Cosmic Acceleration ◽  
Acoustic Oscillations ◽  
Spatial Curvature ◽  
Light Curve Analysis ◽  
Type Ia ◽  
Positive Volume ◽  
Ia Supernovae

Few statements in cosmology can be made without assuming a cosmological model within which to interpret data. Statements about cosmic acceleration are no exception to this rule, and the inferred positive volume acceleration of our universe often quoted in the literature is valid in the context of the standard Friedmann–Lemaître–Robertson–Walker (FLRW) class of spacetimes. Using the Joint Light-curve Analysis (JLA) catalogue of supernovae Type Ia (SNIa), we examine the fit of a class of exact scaling solutions with dynamical spatial curvature formulated in the framework of a scalar averaging scheme for relativistic inhomogeneous spacetimes. In these models, global volume acceleration may emerge as a result of the nonlocal variance between expansion rates of clusters and voids, the latter gaining volume dominance in the late-epoch universe. We find best-fit parameters for a scaling model of backreaction that are reasonably consistent with previously found constraints from SNIa, CMB, and baryon acoustic oscillations data. The quality of fit of the scaling solutions is indistinguishable from that of the ΛCDM model and the timescape cosmology from an Akaike Information Criterion (AIC) perspective. This indicates that a broad class of models can account for the [Formula: see text] expansion history.

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.

A new pressure-parametric cosmological model

2020 ◽  
Vol 35 (25) ◽  
pp. 2050209
Author(s):  
Yan-Hong Yao ◽  
Xin-He Meng
Keyword(s):  
Scalar Fields ◽  
Model Parameters ◽  
Acoustic Oscillations ◽  
Dark Sector ◽  
Type Ia ◽  
Phantom Scalar ◽  
Acceleration Of The Universe ◽  
Expansion Of The Universe ◽  
Ia Supernovae ◽  
The Universe

We put forward a pressure-parametric model to study the tiny deviation from cosmological constant(CC) behavior of the dark sector accelerating the expansion of the Universe. Data from cosmic microwave background (CMB) anisotropies, baryonic acoustic oscillations (BAO), Type Ia supernovae (SN Ia) observation are applied to constrict the model parameters. The constraint results show that such model suffers with [Formula: see text] tension as well. To realize this model more physically, we reconstruct it with the quintessence and phantom scalar fields, and find out that although the model predicts a quintessence-induced acceleration of the Universe at past and present, at some moment of the future, dark energy’s density have a disposition to increase.

PROBING COSMIC ACCELERATION WITH GALAXY REDSHIFT SURVEYS

2011 ◽  
Vol 20 (10) ◽  
pp. 2109-2113
Author(s):  
LUIGI GUZZO
Keyword(s):  
Modern Science ◽  
Short Review ◽  
Cosmic Acceleration ◽  
Acoustic Oscillations ◽  
Redshift Surveys ◽  
The Galaxy ◽  
Type Ia ◽  
Redshift Survey ◽  
Alternative Scenarios ◽  
Ia Supernovae

Redshift surveys of galaxies beyond the local Universe (z ≫ 0.1) are opening up new possibilities to understanding the observed acceleration of cosmic expansion, one of the greatest mysteries of modern science. Baryonic Acoustic Oscillations in the galaxy power spectrum (or correlation function), provide us with a standard rod to measure the expansion history H(z). At the same time, redshift-space distortions in the clustering pattern due to galaxy peculiar motions are a measure of the growth rate of structure f(z). The combination of these two quantities, allows us to distinguish whether cosmic acceleration is due to the existence of a "dark energy" in the cosmic budget, or rather requires a modification of General Relativity. These two radically alternative scenarios are degenerate when considering H(z) alone, as yielded, e.g. by the Hubble diagram of Type Ia supernovae. In this short review paper I will mostly concentrate on the latter measurement, whose potential importance in this context has been recently highlighted. Current results are consistent with the simplest GR-based cosmological constant scenario, but error bars are still large. Detailed forecasts show that next-generation deep surveys optimizing the combination of large volumes and good galaxy sampling will be able to use redshift distortions as a key tool to understand the physical origin of cosmic acceleration. Among these, I introduce the newly started VIMOS Public Extragalactic Redshift Survey (VIPERS) at the ESO VLT, which is building at [Formula: see text] a sample comparable to the local 2dFGRS. Expectations from even larger surveys planned from space-borne observatories such as EUCLID will also be mentioned.

scholarly journals Constraints on $$\sigma _8$$ and degeneracies from linear Nash-Greene perturbations in subhorizon scale

2020 ◽  
Vol 80 (9) ◽  
Author(s):  
Abraão J. S. Capistrano
Keyword(s):  
Large Scale ◽  
Present Model ◽  
Information Criterion ◽  
Matter Content ◽  
Data Sets ◽  
Acoustic Oscillations ◽  
Growth Data ◽  
Microwave Background ◽  
Percentage Difference ◽  
Type Ia

AbstractUsing a joint statistical analysis, we test a four-dimensional FLRW model embedded in a five-dimensional bulk based on the Nash-Greene embedding theorem. Performing a Markov Chain Monte Carlo (MCMC) modelling, we combine observational data sets as those of the recent growth data, the best-fit Planck2018/$$\varLambda $$ Λ CDM parameters on the Cosmic Microwave Background (CMB), the Baryon Acoustic Oscillations (BAO) measurements, the Pantheon Supernovae type Ia and the Hubble parameter data. From linear Nash-Greene fluctuations of the metric, we show the related perturbed equations in longitudinal Newtonian gauge to obtain the evolution of growth matter. A mild alleviation may be obtained from the degeneracies on the model parameter analyzing the $$\sigma $$ σ tension between the growth amplitude factor and the matter content in the plane $$(\sigma _8$$ ( σ 8 -$$\varOmega _m)$$ Ω m ) on the observations from CMB and Large Scale Structure (LSS) probes. The Akaike Information Criterion (AIC) is also applied and we find a relative statistical consistence of the present model with both $$\varLambda $$ Λ CDM and wCDM models lower than 1$$\%$$ % of percentage difference at early times on the evolution of the Hubble function H(z). We also apply the Om(z) diagnosis to distinguish the present model from $$\varLambda $$ Λ CDM and wCDM models.

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 H0LiCOW – XIII. A 2.4 per cent measurement of H0 from lensed quasars: 5.3σ tension between early- and late-Universe probes

2019 ◽  
Vol 498 (1) ◽  
pp. 1420-1439 ◽  
Author(s):  
Kenneth C Wong ◽  
Sherry H Suyu ◽  
Geoff C-F Chen ◽  
Cristian E Rusu ◽  
Martin Millon ◽  
...  
Keyword(s):  
Time Delay ◽  
Cold Dark Matter ◽  
Cosmological Parameters ◽  
Hubble Constant ◽  
Joint Analysis ◽  
Type Ia Supernovae ◽  
Acoustic Oscillations ◽  
Type Ia ◽  
Measured Time ◽  
Ia Supernovae

ABSTRACT We present a measurement of the Hubble constant (H0) and other cosmological parameters from a joint analysis of six gravitationally lensed quasars with measured time delays. All lenses except the first are analysed blindly with respect to the cosmological parameters. In a flat Λ cold dark matter (ΛCDM) cosmology, we find $H_{0} = 73.3_{-1.8}^{+1.7}~\mathrm{km~s^{-1}~Mpc^{-1}}$, a $2.4{{\ \rm per\ cent}}$ precision measurement, in agreement with local measurements of H0 from type Ia supernovae calibrated by the distance ladder, but in 3.1σ tension with Planck observations of the cosmic microwave background (CMB). This method is completely independent of both the supernovae and CMB analyses. A combination of time-delay cosmography and the distance ladder results is in 5.3σ tension with Planck CMB determinations of H0 in flat ΛCDM. We compute Bayes factors to verify that all lenses give statistically consistent results, showing that we are not underestimating our uncertainties and are able to control our systematics. We explore extensions to flat ΛCDM using constraints from time-delay cosmography alone, as well as combinations with other cosmological probes, including CMB observations from Planck, baryon acoustic oscillations, and type Ia supernovae. Time-delay cosmography improves the precision of the other probes, demonstrating the strong complementarity. Allowing for spatial curvature does not resolve the tension with Planck. Using the distance constraints from time-delay cosmography to anchor the type Ia supernova distance scale, we reduce the sensitivity of our H0 inference to cosmological model assumptions. For six different cosmological models, our combined inference on H0 ranges from ∼73 to 78 km s−1 Mpc−1, which is consistent with the local distance ladder constraints.

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