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Modern cosmology rests on the working assumption that the Universe is isotropic and homogeneous at large scales. Here, we document a number of anomalous observations pointing to an anisotropic Universe in a direction consistent with the CMB…

Cosmology and Nongalactic Astrophysics · Physics 2022-03-22 Eoin Ó Colgáin

Wide area cosmological surveys enable investigation of whether dark energy properties are the same in different directions on the sky. Cosmic microwave background observations strongly restrict any dynamical effects from anisotropy, in an…

Cosmology and Nongalactic Astrophysics · Physics 2013-02-05 Stephen A. Appleby , Eric V. Linder

Accurate component separation of full-sky maps in the radio and microwave frequencies, such as the cosmic microwave background (CMB), relies on a thorough understanding of the statistical properties of the Galactic foreground emissions.…

Cosmology and Nongalactic Astrophysics · Physics 2021-07-14 Fazlu Rahman , Pravabati Chingangbam , Tuhin Ghosh

A previous work (Monteser\'in et al. 2008) estimated the CMB variance from the three-year WMAP data, finding a lower value than expected from Gaussian simulations using the WMAP best-fit cosmological model. We repeat the analysis on the…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 M. Cruz , P. Vielva , E. Martínez-González , R. B. Barreiro

Non-linear evolution of density fluctuations yields secondary anisotropies in the cosmic microwave background (CMB), which are correlated with the same density fluctuations that can be measured by weak lensing (WL) surveys. We study the…

We examine the extent to which galactic and extragalactic foregrounds can hamper the detection of primordial Cosmic Microwave Background (CMB) anisotropies. We limit our discussion to intermediate angular scales, $10^{\prime}\lsim \theta…

Astrophysics · Physics 2009-09-25 L. Toffolatti

The weak lensing effect on the cosmic microwave background (CMB) induces distortions in spatial pattern of CMB anisotropies, and statistical properties of CMB anisotropies become a weakly non-Gaussian field. We first summarize the weak…

Cosmology and Nongalactic Astrophysics · Physics 2014-03-17 Toshiya Namikawa

Gaussianity and statistical isotropy of the Universe are modern cosmology's minimal set of hypotheses. In this work we introduce a new statistical test to detect observational deviations from this minimal set. By defining the temperature…

Cosmology and Nongalactic Astrophysics · Physics 2009-09-30 Thiago S. Pereira , L. Raul Abramo

Cosmic microwave background anisotropies provide a vast amount of cosmological information. Their full physical content and detailed structure can be understood in a simple and intuitive fashion through a systematic investigation of the…

Astrophysics · Physics 2009-10-28 Wayne Hu , Naoshi Sugiyama , Joseph Silk

Cosmic microwave background observations are most commonly analyzed by estimating the power spectrum. In the limit where the CMB statistics are perfectly Gaussian, this extracts all the information, but the CMB also contains detectable…

Cosmology and Nongalactic Astrophysics · Physics 2011-11-09 Kendrick M. Smith

The Cosmic Microwave Background (CMB) anisotropy constrains the geometry of the Universe because the positions of the acoustic peaks of the angular power spectrum depend strongly on the curvature of underlying three-dimensional space. In…

Astrophysics · Physics 2009-11-13 J. Dunkley , M. Bucher , P. G. Ferreira , K. Moodley , C. Skordis

The cosmic microwave background (CMB) is gravitationally lensed by large-scale structure, which distorts observations of the primordial anisotropies in any given direction. Averaged over the sky, this important effect is routinely modelled…

Cosmology and Nongalactic Astrophysics · Physics 2021-03-17 G. Fabbian , J. Carron , A. Lewis , M. Lembo

Motivated by the large-scale asymmetry observed in the cosmic microwave background sky, we consider a specific class of anisotropic cosmological models -- Bianchi type VII_h -- and compare them to the WMAP first-year data on large angular…

Astrophysics · Physics 2009-11-10 T. R. Jaffe , A. J. Banday , H. K. Eriksen , K. M. Gorski , F. K. Hansen

The cosmic microwave background anisotropies produced by active seeds, such as topological defects, have been computed recently for a variety of models by a number of authors. In this paper we show how the generic features of the…

General Relativity and Quantum Cosmology · Physics 2017-10-04 Alain Riazuelo , Nathalie Deruelle

We study the possible contribution of a stochastic gravitational wave background to the anisotropy of the cosmic microwave background (CMB) in cold and mixed dark matter (CDM and MDM) models. We test this contribution against recent…

Astrophysics · Physics 2009-10-31 A. Melchiorri , M. V. Sazhin , V. V. Shulga , N. Vittorio

A theory of quantum-mechanical generation of cosmological perturbations is considered. The conclusion of this study is that if the large-angular-scale anisotropy in the cosmic microwave background radiation is caused by the long-wavelength…

General Relativity and Quantum Cosmology · Physics 2009-09-25 L. P. Grishchuk

Radio interferometers are well suited to studies of both total intensity and polarized intensity fluctuations of the cosmic microwave background radiation, and they have been used successfully in measurements of both the primary and…

Astrophysics · Physics 2007-05-23 A. C. S. Readhead , T. J. Pearson

In the first part of this work, I review the theoretical framework of cosmological perturbation theory necessary to understand the generation and evolution of cosmic microwave background (CMB) anisotropies. Using analytical and numerical…

Astrophysics · Physics 2009-09-29 Roberto Trotta

Band-power estimates of cosmic microwave background fluctuations are now routinely used to place constraints on cosmological parameters. For this to be done in a rigorous fashion, the full likelihood function of band-power estimates must be…

Astrophysics · Physics 2011-05-23 J. G. Bartlett , M. Douspis , A. Blanchard , M. Le Dour

We repeat and extend the analysis of Eriksen et al 2004 and Hansen et al 2004 testing the isotropy of the Cosmic Microwave Background (CMB) fluctuations. We find that the hemispherical power asymmetry previously reported for the largest…

Astrophysics · Physics 2014-11-18 F. K. Hansen , A. J. Banday , K. M. Gorski , H. K. Eriksen , P. B. Lilje
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