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Under the assumption that they are standard(isable) candles, the lightcurves of Type Ia supernovae have been analyzed in the framework of the standard Friedmann-Lema\^itre-Robertson-Walker cosmology to conclude that the expansion rate of…

Cosmology and Nongalactic Astrophysics · Physics 2025-02-14 Mohamed Rameez

We constrain several models of the early Universe that predict a statistical anisotropy of the cosmic microwave background (CMB) sky. We make use of WMAP9 maps deconvolved with beam asymmetries. As compared to previous releases of WMAP…

Cosmology and Nongalactic Astrophysics · Physics 2014-03-03 Sabir Ramazanov , Grigory Rubtsov

Observational tests for the Cosmological Principle are reviewed. Assuming the FRW metric we then summarize estimates of cosmological parameters from various data sets, in particular the Cosmic Microwave Background and the 2dF galaxy…

Astrophysics · Physics 2008-11-26 Ofer Lahav

We study the conditions for the consistency of the Friedmann-Robertson-Walker (FRW) metric with the dynamical Chern-Simons modified gravity. It turns out to be that in this situation the accelerated expansion of the Universe takes place,…

High Energy Physics - Theory · Physics 2011-07-14 C. Furtado , J. R. Nascimento , A. Yu. Petrov , A. F. Santos

We consider directly the equations by which matter imposes anisotropies on freely propagating background radiation, leading to a new way of using anisotropy measurements to limit the deviations of the Universe from a…

Astrophysics · Physics 2016-08-30 Roy Maartens , George F. R. Ellis , William R. Stoeger

The standard cosmological model predicts statistically isotropic cosmic microwave background (CMB) fluctuations characterized by the CMB temperature coefficients $a_{\ell m}$ being independent Gaussian random variables with zero mean and…

Cosmology and Nongalactic Astrophysics · Physics 2026-03-17 Joann Jones , Craig J. Copi , Glenn D. Starkman , Yashar Akrami

It is argued that cosmic chronometers yield estimates of the spatially averaged expansion rate even in a universe that is not well described by a global FLRW model - as long as the Universe is statistically homogeneous and isotropic with a…

Cosmology and Nongalactic Astrophysics · Physics 2021-06-11 S. M. Koksbang

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

The assumption of isotropy -- that the Universe looks the same in all directions on large scales -- is fundamental to the standard cosmological model. This model forms the building blocks of essentially all of our cosmological knowledge to…

Cosmology and Nongalactic Astrophysics · Physics 2022-12-29 Jessica A. Cowell , Suhail Dhawan , Hayley J. Macpherson

We present local extrema studies of two models that introduce a preferred direction into the observed cosmic microwave background (CMB) temperature field. In particular, we make a frequentist comparison of the one- and two-point statistics…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-20 Zhen Hou , A. J. Banday , K. M. Gorski , N. E. Groeneboom , H. K. Eriksen

The cosmological principle, as the cornerstone of the standard cosmological model, requires that the Universe be homogeneous and isotropic on large scales. As a fundamental assumption, it is constantly subjected to testing via various…

Cosmology and Nongalactic Astrophysics · Physics 2026-04-21 Jianping Hu , Chao Geng , Xuandong Jia , Zhaoyu Zuo , Taozhi Yang , Fayin Wang

The cosmic microwave background radiation provides unique constraints on cosmological models. In this Letter we present a summary of the spatial properties of the cosmic microwave background radiation based on the full 4 years of COBE DMR…

Anisotropic cosmological models have been gaining attention due to various observational hints of large-scale anisotropies. One of the most surprising evidences for the latter is the discovery of a dipole-like directional variation in…

Cosmology and Nongalactic Astrophysics · Physics 2025-08-08 Boris Hoi-Lun Ng , Ming-Chung Chu

The simplest theory describing large-scale redshift-space distortions (RSD), based on linear theory and distant galaxies, depends on the growth of cosmological structure, suggesting that strong tests of General Relativity can be constructed…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-18 Lado Samushia , Will J. Percival , Alvise Raccanelli

The cosmological principle has been verified using electromagnetic (EM) observations. However its verification with high accuracy is challenging due to various foregrounds and selection effects, and possible violation of the cosmological…

Cosmology and Nongalactic Astrophysics · Physics 2023-09-14 Mingzheng Li , Pengjie Zhang , Wen Zhao

Accurate measurements of the Cosmic Microwave Background (CMB) anisotropy call for high precision and reliability of the in-flight calibration. For extended surveys the CMB dipole provides an excellent calibration source at frequencies…

Astrophysics · Physics 2009-11-10 B. Cappellini , D. Maino , G. Albetti , P. Platania , R. Paladini , A. Mennella , M. Bersanelli

In this paper the next attempt is made to clarify the nature of the Euclidean behavior of the boundary in the angular size-redshift cosmological test. It is shown experimentally that this can be explained by the selection determined by…

Cosmology and Nongalactic Astrophysics · Physics 2015-01-13 V. R. Amirkhanyan

According to the Cosmological Principle an observer stationary with respect to the comoving coordinates of the expanding universe should find the redshift distribution of distant quasars to be isotropic. However, the observed redshift…

Cosmology and Nongalactic Astrophysics · Physics 2025-09-01 Ashok K. Singal

The nature of dark matter is increasingly constrained by cosmological data. In this paper, we examine the implications of the Cosmic Microwave Background anisotropy limits on the density of cold dark matter under different theoretical…

Astrophysics · Physics 2009-11-07 A. Melchiorri , J. Silk

Observations of distant supernovae indicate that the Universe is now in a phase of accelerated expansion the physical cause of which is a mystery. Formally, this requires the inclusion of a term acting as a negative pressure in the…

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