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Standard models of galaxy formation predict that matter distribution is statistically homogeneous and isotropic and characterized by (i) spatial homogeneity for r<10 Mpc/h, (ii) small-amplitude structures of relatively limited size (i.e.,…

Cosmology and Nongalactic Astrophysics · Physics 2011-09-02 Francesco Sylos Labini

The standard cosmological model, which assumes statistical isotropy and parity invariance, predicts the absence of correlations between even-parity and odd-parity observables of the cosmic microwave background (CMB). Contrary to these…

Beam asymmetries result in statistically-anisotropic cosmic microwave background (CMB) maps. Typically, they are studied for their effects on the CMB power spectrum, however they more closely mimic anisotropic effects such as gravitational…

Cosmology and Nongalactic Astrophysics · Physics 2010-10-05 Duncan Hanson , Antony Lewis , Anthony Challinor

The interpretation of cosmological observations relies on a notion of an average Universe, which is usually considered as the homogeneous and isotropic Friedmann-Lema\^itre-Robertson-Walker (FLRW) model. However, inhomogeneities may…

Cosmology and Nongalactic Astrophysics · Physics 2021-11-24 Michel-Andrès Breton , Pierre Fleury

The observed large-scale alignment of polarization angles and galaxy axis have been challenging the fundamental assumption of homogeneity and isotropy in standard cosmology since more than two decades. The intergalactic magnetic field, and…

Cosmology and Nongalactic Astrophysics · Physics 2022-04-07 Prabhakar Tiwari , Pankaj Jain

A new method for modelling spherically symmetric inhomogeneities is applied to the formation of clusters in an expanding Universe. We impose simple initial velocity and density perturbations of finite extent and we investigate the…

Astrophysics · Physics 2009-10-31 Y. Dabrowski , M. P. Hobson , A. N. Lasenby , C. J. L. Doran

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

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

Homogeneity is a crucial, but poorly tested, assumption in cosmology. We introduce a new approach which allows us to place limits on the presence of localized structures within essentially our entire observable volume, using cosmic…

Cosmology and Nongalactic Astrophysics · Physics 2014-09-15 James. P. Zibin , Adam Moss

The cosmic microwave background radiation allows us to measure both the geometry and topology of the universe. It has been argued that the COBE-DMR data already rule out models that are multiply connected on scales smaller than the particle…

Astrophysics · Physics 2009-10-31 Neil J. Cornish , David N. Spergel

Analyses of the cosmic microwave background (CMB) radiation maps made by the Wilkinson Microwave Anisotropy Probe (WMAP) have revealed anomalies not predicted by the standard inflationary cosmology. In particular, the power of the…

Earth and Planetary Astrophysics · Physics 2014-11-20 V. Dikarev , O. Preuss , S. Solanki , H. Krueger , A. Krivov

We aim to present a tutorial on the detection, parameter estimation and statistical analysis of compact sources (far galaxies, galaxy clusters and Galactic dense emission regions) in cosmic microwave background observations. The topic is of…

Cosmology and Nongalactic Astrophysics · Physics 2011-01-05 D. Herranz , P. Vielva

Using the exact Lemaitre-Bondi-Tolman solution with a non-vanishing cosmological constant $\Lambda$, we investigate how the presence of a local spherically-symmetric inhomogeneity can affect apparent cosmological observables, such as the…

Cosmology and Nongalactic Astrophysics · Physics 2015-09-01 Antonio Enea Romano , Misao Sasaki , Alexei A. Starobinsky

In this review, I outline the use of galaxy correlations to constrain cosmological parameters. As with the Cosmic Microwave Background (CMB), the density of dark and baryonic matter imprints important scales on the fluctuations of matter…

Astrophysics · Physics 2008-11-26 Robert C. Nichol

A lack of correlations in the microwave background temperature between sky directions separated by angles larger than 60 degrees has recently been confirmed by data from the Planck satellite. This feature arises as a random occurrence…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-17 A. Yoho , C. J. Copi , G. D. Starkman , A. Kosowsky

The current suite of results from Cosmic Microwave Background anisotropy experiments is fulfilling the promise of providing extraordinary levels of discrimination between cosmological models. We calculate a binned anisotropy power spectrum,…

Astrophysics · Physics 2007-05-23 Elena Pierpaoli , Douglas Scott , Martin White

There is tentative evidence for a mismatch between the rest frames of matter and the cosmic microwave background, the "quasar dipole anomaly". We consider such a dipole in tilted anisotropic models, for a range of scenarios and sources:…

Cosmology and Nongalactic Astrophysics · Physics 2025-12-04 Alicia Martín , Constantinos Skordis , Deaglan J. Bartlett , Harry Desmond , Pedro G. Ferreira , Tariq Yasin

On large angular scales (greater than about 60 degrees), the two-point angular correlation function of the temperature of the cosmic microwave background (CMB), as measured (outside of the plane of the Galaxy) by the Wilkinson Microwave…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 Devdeep Sarkar , Dragan Huterer , Craig J. Copi , Glenn D. Starkman , Dominik J. Schwarz

Cosmic structure on the largest scales preserves the pattern laid down by quantum fluctuations of gravity in the early universe on scales comparable to inflationary horizons. It is proposed here that fluctuations create physical…

Cosmology and Nongalactic Astrophysics · Physics 2024-04-01 Craig Hogan

The microwave sky shows unexpected features at the largest angular scales, among them the alignments of the dipole, quadrupole and octopole. Motivated by recent X-ray cluster studies, we investigate the possibility that local structures at…

Astrophysics · Physics 2008-11-26 Aleksandar Rakic , Syksy Rasanen , Dominik J. Schwarz