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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…

Cosmology and Nongalactic Astrophysics · Physics 2019-09-20 Célia Desgrange , Asta Heinesen , Thomas Buchert

This paper presents a general averaging procedure for a set of observers which are tilted with respect to the cosmological matter fluid. After giving the full set of equations describing the local dynamics, we define the averaging procedure…

General Relativity and Quantum Cosmology · Physics 2009-04-22 J. Larena

We use the new SNe Ia discovered by the SDSS-II Supernova Survey together with additional supernova datasets as well as observations of the cosmic microwave background and baryon acoustic oscillations to constrain cosmological models. This…

Dark energy and the accelerated expansion of the universe have been the direct predictions of the distant supernovae Ia observations which are also supported, indirectly, by the observations of the CMB anisotropies, gravitational lensing…

Astrophysics · Physics 2008-11-26 Ram Gopal Vishwakarma

While recent supernova cosmology research has benefited from improved measurements, current analysis approaches are not statistically optimal and will prove insufficient for future surveys. This paper discusses the limitations of current…

The existing set of type Ia supernovae (SNe Ia) is now sufficient to detect oscillatory deviations from the canonical $\Lambda$CDM cosmology. We determine that the Fourier spectrum of the Pantheon data set of spectroscopically well-observed…

Astrophysics of Galaxies · Physics 2019-04-22 Sasha R. Brownsberger , Christopher W. Stubbs , Daniel M. Scolnic

We study different one-parametric models of type Ia Supernova magnitude evolution on cosmic time scales. Constraints on cosmological and Supernova evolution parameters are obtained by combined fits on the actual data coming from Supernovae,…

Cosmology and Nongalactic Astrophysics · Physics 2010-04-16 Sebastian Linden , Jean-Marc Virey , Andre Tilquin

Using the Bayesian theory of model comparison, a new cosmological model due to John and Joseph [M. V. John and K. Babu Joseph, Phys. Rev. D 61, 87304 (2000)] is compared with the standard \Omega_{\Lambda} \neq 0 cosmological model. Their…

Astrophysics · Physics 2009-11-07 Moncy V. John , J. V. Narlikar

We discuss several issues related to a recent proposal for defining classical spatial averages to be used in the so-called cosmological backreaction problem. In the large averaging-volume limit all gauge dependence disappears and different…

General Relativity and Quantum Cosmology · Physics 2011-07-14 Giovanni Marozzi

Model-independent estimations for the spatial curvature not only provide a test for the fundamental Copernican principle assumption, but also can effectively break the degeneracy between curvature and dark energy properties. In this paper,…

Cosmology and Nongalactic Astrophysics · Physics 2016-12-28 Zhengxiang Li , Guo-Jian Wang , Kai Liao , Zong-Hong Zhu

There has been increasing interest by cosmologists in applying Bayesian techniques, such as Bayesian Evidence, for model selection. A typical example is in assessing whether observational data favour a cosmological constant over evolving…

Astrophysics · Physics 2009-11-13 G. Efstathiou

Recent observations of high-redshift Type Ia supernovae have placed stringent constraints on the cosmological constant $\Lambda$. We explore the implications of these SNe observations for cosmological models in which a classically evolving…

Astrophysics · Physics 2009-10-30 Joshua A. Frieman , Ioav Waga

It is necessary to make assumptions in order to derive models to be used for cosmological predictions and comparison with observational data. In particular, in standard cosmology the spatial curvature is assumed to be constant and zero (or…

General Relativity and Quantum Cosmology · Physics 2019-05-14 A. A. Coley

This article revisits the interpretation of cosmic probes such as SNIa and BAO under a two-regions model of the universe. Standard cosmological analyses assume homogeneity, yet observations are predominantly conducted in overdense regions…

Cosmology and Nongalactic Astrophysics · Physics 2025-02-21 Vincent Deledicque

We review various cosmological models with a local underdense region (local void) and the averaged models with the backreaction of inhomogeneities, which have been proposed to explain (without assuming a positive cosmological constant) the…

Cosmology and Nongalactic Astrophysics · Physics 2009-06-09 Kenji Tomita

Bayesian model averaging is a procedure to obtain parameter constraints that account for the uncertainty about the correct cosmological model. We use recent cosmological observations and Bayesian model averaging to derive tight limits on…

Cosmology and Nongalactic Astrophysics · Physics 2012-06-07 M. Vardanyan , R. Trotta , J. Silk

By using the Sloan Digital Sky Survey (SDSS) first year type Ia supernova (SN Ia) compilation, we compare two different approaches (traditional \chi^2 and complete likelihood) to determine parameter constraints when the magnitude dispersion…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-27 B. L. Lago , M. O. Calvão , S. E. Jorás , R. R. R. Reis , I. Waga , R. Giostri

We review the use of Bayesian Model Averaging in astrophysics. We first introduce the statistical basis of Bayesian Model Selection and Model Averaging. We discuss methods to calculate the model-averaged posteriors, including Markov Chain…

Instrumentation and Methods for Astrophysics · Physics 2013-02-08 David Parkinson , Andrew R. Liddle

Cosmological parameter uncertainties are often stated assuming a particular model, neglecting the model uncertainty, even when Bayesian model selection is unable to identify a conclusive best model. Bayesian model averaging is a method for…

Cosmology and Nongalactic Astrophysics · Physics 2010-12-23 David Parkinson , Andrew R. Liddle