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We analyse the anisotropy of the cosmic microwave background (CMB) in hyperbolic universes possessing a non-trivial topology with a fundamental cell having an infinitely long horn. The aim of this paper is twofold. On the one hand, we show…

Astrophysics · Physics 2009-11-10 Ralf Aurich , Sven Lustig , Frank Steiner , Holger Then

The CMB anisotropy depends sensitively upon the slope and amplitude of primordial density and gravitational wave fluctuations, the baryon density, the Hubble constant, the cosmological constant, the ionization history, {\it etc.} We report…

Astrophysics · Physics 2009-09-25 J. Richard Bond , Richard L. Davis , Paul J. Steinhardt

When considering the statistical properties of a bundle of cosmic microwave background (CMB) photons propagating through space, the effect of `mixing geodesics' appears with a distinct signature that depends on the geometry of space. In a…

Astrophysics · Physics 2011-05-10 V. G. Gurzadyan , S. Torres

The COBE detection of microwave anisotropies provides the best way of fixing the amplitude of cosmological fluctuations on the largest scales. We discuss the impact of this new, precise normalization and give fitting formulae for the…

Astrophysics · Physics 2009-08-18 Martin White , Douglas Scott

The Cosmic Microwave Background (CMB) anisotropies measurements can provide many clues about the Universe. Although the common belief is that they will allow a very precise measurement of the cosmological parameters (that is, the current…

Astrophysics · Physics 2007-05-23 Alain Riazuelo , David Langlois

We analyze the spectrum of cosmic microwave background (CMB) anisotropies in the timescape cosmology: a potentially viable alternative to homogeneous isotropic cosmologies without dark energy. We exploit the fact that the timescape…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-18 M. Ahsan Nazer , David L. Wiltshire

We have investigated the cosmic microwave background (CMB) anisotropy in closed multiply connected universes (flat and hyperbolic) with low matter density. We show that the COBE constraints on these low matter density models with…

Astrophysics · Physics 2016-08-30 Kaiki Taro Inoue

Measurements of CMB anisotropy and, more recently, polarization have played a very important role allowing precise determination of various parameters of the `standard' cosmological model. The expectation of the paradigm of inflation and…

Astrophysics · Physics 2008-11-26 Tarun Souradeep

Recent satellite observations have revealed significant anisotropy in the cosmic microwave background (CMB) radiation, a phenomenon that had previously been detected but received limited attention due to its subtlety. With the advent of…

General Relativity and Quantum Cosmology · Physics 2025-02-10 S. Davood Sadatian , Amir Sabouri , Zahra Davari

Measurements of CMB anisotropy and, more recently, polarization have played a very important role in cosmology. Besides precise determination of various parameters of the `standard' cosmological model, observations have also established…

Cosmology and Nongalactic Astrophysics · Physics 2011-06-02 Tarun Souradeep

Deviations from statistical isotropy can be modeled in various ways, for instance, anisotropic cosmological models (Bianchi models), compact topologies and presence of primordial magnetic field. Signature of anisotropy manifests itself in…

Cosmology and Nongalactic Astrophysics · Physics 2010-05-12 Nidhi Joshi , Sanjay Jhingan , Tarun Souradeep , Amir Hajian

Cosmic Microwave Background (CMB) anisotropy encodes a lot of information about our Universe. In this paper we take the ground-based CMB observations (GCMB), including the South Pole Telescope (SPT), SPTpol and the Atacama Cosmology…

Cosmology and Nongalactic Astrophysics · Physics 2020-07-01 Ke Wang , Qing-Guo Huang

Forthcoming cosmic microwave background experiments (CMB) will provide precise new tests of structure-formation theories. The geometry of the Universe may be determined robustly, and the classical cosmological parameters, such as the…

Astrophysics · Physics 2007-05-23 Marc Kamionkowski

Measurements of the cosmic microwave background (CMB) temperature anisotropies have revealed a dipolar asymmetry in power at the largest scales, in apparent contradiction with the statistical isotropy of standard cosmological models. The…

Cosmology and Nongalactic Astrophysics · Physics 2018-03-07 D. Contreras , J. Hutchinson , A. Moss , D. Scott , J. P. Zibin

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…

We study the possibility for constraining the topology of the Universe by means of the matched circles statistic applied to polarised cosmic microwave background (CMB) anisotropy maps. The advantages of using the CMB polarisation maps in…

Cosmology and Nongalactic Astrophysics · Physics 2018-02-09 P. Bielewicz , A. J. Banday , K. M. Gorski

Fundamental information about the Universe is encoded in anisotropies of the Cosmic Microwave Background (CMB) radiation. To make full use of this information, an experiment must image the entire sky with the angular resolution,…

The full sky measurements of the Cosmic Microwave Background (CMB) temperature anisotropies by $\textit{WMAP}$ and $\textit{Planck}$ have highlighted the presence of several unexpected isotropy-breaking features on the largest angular…

Cosmology and Nongalactic Astrophysics · Physics 2024-12-18 Gabriel Jung , Nabila Aghanim , Jenny Sorce , Benjamin Seidel , Klaus Dolag , Marian Douspis

Non-trivial spatial topology of the Universe can imprint potentially observable signatures on the cosmic microwave background (CMB). In this study, we investigate how deviations from the standard nearly-scale-free primordial power spectrum…

We revisit the observational constraints on compact(closed) hyperbolic(CH) models from cosmic microwave background(CMB). We carry out Bayesian analyses for CH models with volume comparable to the cube of the present curvature radius using…

Astrophysics · Physics 2009-11-06 Kaiki Taro Inoue