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The Hubble tension seems to be a crisis with $\sim5\sigma$ discrepancy between the most recent local distance ladder measurement from type Ia supernovae calibrated by Cepheids and the global fitting constraint from the cosmic microwave…

Cosmology and Nongalactic Astrophysics · Physics 2022-09-19 Rong-Gen Cai , Zong-Kuan Guo , Shao-Jiang Wang , Wang-Wei Yu , Yong Zhou

In the standard model of cosmology, the universe is described by a Robertson-Walker spacetime, while its matter/energy content is modeled by a perfect fluid with three components corresponding to matter/dust, radiation and a cosmological…

General Relativity and Quantum Cosmology · Physics 2013-06-14 Thomas-Paul Hack

In `entropic cosmology', instead of a cosmological constant $\Lambda$, an extra driving term is added to the Friedmann equation and the acceleration equation, taking into account the entropy and the temperature on the horizon of the…

Cosmology and Nongalactic Astrophysics · Physics 2013-03-14 Nobuyoshi Komatsu , Shigeo Kimura

In this paper, inspired by the ultraviolet deformation of the Friedmann-Lema\^{\i}tre-Robertson-Walker geometry in loop quantum cosmology, we formulate an infrared-modified cosmological model. We obtain the associated deformed Friedmann and…

General Relativity and Quantum Cosmology · Physics 2016-08-12 Mohammad Ali Gorji

Light is affected by local inhomogeneities in its propagation, which may alter distances and so cosmological parameter estimation. In the era of precision cosmology, the presence of inhomogeneities may induce systematic errors if not…

Cosmology and Nongalactic Astrophysics · Physics 2014-03-11 J. A. S. Lima , V. C. Busti , R. C. Santos

We challenge the widely held belief that the cosmological principle is an obvious consequence of the observed isotropy of the cosmic microwave background radiation, combined with the Copernican principle. We perform a detailed analysis of a…

Astrophysics · Physics 2009-10-31 R. K. Barrett , C. A. Clarkson

We examine the properties of a recently proposed observationally viable alternative to homogeneous cosmology with smooth dark energy, the timescape cosmology. In the timescape model cosmic acceleration is realized as an apparent effect…

Cosmology and Nongalactic Astrophysics · Physics 2009-12-30 David L. Wiltshire

We analyze two different algorithms for constructing weakly inhomogeneous models for the low-redshift Universe, in order to provide a tool for testing the geodesic dynamics, within the sphere of validity for the Universe acceleration. We…

General Relativity and Quantum Cosmology · Physics 2020-07-14 P. Marcoccia , G. Montani

Under the assumption that the concordance Lambda cold dark matter (CDM) model is the correct model, we test the cosmic microwave background (CMB) anisotropy data for systematic effects by examining the band pass temperature residuals with…

Astrophysics · Physics 2007-05-23 Louise M. Griffiths , Charles H. Lineweaver

We investigate the effect of averaging inhomogeneities on expansion and large-scale structure growth observables using the exact and covariant framework of Macroscopic Gravity (MG). It is well-known that applying the Einstein's equations…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-24 Tharake Wijenayake , Mustapha Ishak

The search for the physical mechanism underlying the observational evidence for the acceleration of the recent universe is a compelling goal of modern fundamental cosmology. Here we quantitatively study a class of homogeneous and isotropic…

Cosmology and Nongalactic Astrophysics · Physics 2022-04-19 E. -A. Kolonia , C. J. A. P. Martins

Kinematical and dynamical properties of a generic inhomogeneous cosmological model, spatially averaged with respect to free-falling (generalized fundamental) observers, are investigated for the matter model irrotational dust. Paraphrasing a…

General Relativity and Quantum Cosmology · Physics 2013-06-12 Thomas Buchert , Charly Nayet , Alexander Wiegand

Based on the Lema\^itre-Tolman-Bondi (LTB) metric we consider two flat inhomogeneous big-bang models. We aim at clarifying, as far as possible analytically, basic features of the dynamics of the simplest inhomogeneous models and to point…

General Relativity and Quantum Cosmology · Physics 2016-05-25 Eddy G. Chirinos Isidro , Cristofher Zuñiga Vargas , Winfried Zimdahl

The luminosity distance can be used to determine the properties of large scale structure around the observer. To this purpose we develop a new inversion method to map luminosity distance to a LTB metric based on the use of the exact…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-04 Antonio Enea Romano , Hsu-Wen Chiang , Pisin Chen

We study the effects of inhomogeneities on the evolution of the Universe, by considering a range of cosmological models with discretized matter content. This is done using exact and fully relativistic methods that exploit the symmetries in…

General Relativity and Quantum Cosmology · Physics 2015-06-17 Timothy Clifton , Daniele Gregoris , Kjell Rosquist , Reza Tavakol

Inhomogeneous and anisotropic cosmologies are modeled withing the framework of scalar-tensor gravity theories. The inhomogeneities are calculated to third-order in the so-called long-wavelength iteration scheme. We write the solutions for…

General Relativity and Quantum Cosmology · Physics 2011-08-17 G. L. Comer , Nathalie Deruelle , David Langlois

We explore the large angular scale temperature anisotropies in the cosmic microwave background (CMB) due to homogeneous local dust-filled voids in a flat Friedmann-Robertson-Walker universe with a cosmological constant. In comparison with…

Astrophysics · Physics 2008-11-26 Kaiki Taro Inoue , Joseph Silk

Cosmic microwave background (CMB) anisotropies and density fluctuations are calculated for flat cold dark matter (CDM) models with a wide range of parameters, i.e., $\Omega_0, h$ and $\Omega_B$ for both standard recombination and various…

Astrophysics · Physics 2009-10-22 Naoshi Sugiyama

Providing quantitative interpretation of coherent nonlinear microscopy images, such as third-harmonic generation (THG), is generally hampered by the complex phase-matching conditions, especially in the presence of sample linear…

Optics · Physics 2026-03-09 Mohammad Reza Farhadinia , Nicolas Olivier

A class of cosmological solutions of higher dimensional Einstein field equations with the energy-momentum tensor of a homogeneous, isotropic fluid as the source are considered with an anisotropic metric that includes the direct sum of a…

General Relativity and Quantum Cosmology · Physics 2013-10-24 Ozgur Akarsu , Tekin Dereli