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The cosmological principle is a cornerstone of the standard cosmological model. However, recent observations suggest potential deviations from this assumption, hinting at a small anisotropic expansion. Such an expansion can arise from…

Cosmology and Nongalactic Astrophysics · Physics 2025-09-23 Jose L. Palacios-Córdoba , J. Bayron Orjuela-Quintana , Gabriela A. Valencia-Zuñiga , César A. Valenzuela-Toledo

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

Models of structure formation with a cosmological constant $\Lambda$ provide a good fit to the observed power spectrum of galaxy clustering. However, they suffer from several problems. Theoretically, it is difficult to understand why the…

Astrophysics · Physics 2010-11-30 K. Coble , S. Dodelson , J. Frieman

We calculate the anisotropies in the cosmic microwave background induced by long-wavelength primordial gravitational waves in a universe with negative spatial curvature, such as are produced in the ``open inflation'' scenario. The impact of…

Astrophysics · Physics 2009-10-30 Wayne Hu , Martin White

The spectral variation of the cosmic microwave background (CMB) as observed by WMAP was tested using foreground reduced WMAP5 data, by producing subtraction maps at the 1$^\circ$ angular resolution between the two cosmological bands of V…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 Bi-Zhu Jiang , Richard Lieu , Shuang-Nan Zhang , Bart Wakker

I review the general aspects of cosmological parameter estimation from observations of the cosmic microwave background (CMB) temperature anisotropies in the framework of inflationary adiabatic models. The most recent CMB datasets are…

Astrophysics · Physics 2009-10-31 A. Balbi

I explain the origin and evolution of anisotropies in the Cosmic Microwave Background (CMB) and argue that upcoming experiments will measure cosmological and fundamental parameters very accurately. Most of the paper focuses on present data,…

High Energy Physics - Phenomenology · Physics 2014-11-17 Scott Dodelson

In this manuscript, we investigate the patterns satisfied by the cosmological anisotropy under the hypothesis of the observers being co-moving with a perfect fluid whose induced space sections are homogeneous with vanishing scalar…

General Relativity and Quantum Cosmology · Physics 2021-03-31 Leandro G. Gomes

We study the effects of negative spatial curvature on the statistics of inhomogeneities in open cosmological models. In particular we examine the suppression of large-separation correlations in density and gravitational potential…

Astrophysics · Physics 2009-10-22 Albert Stebbins , R. R. Caldwell

Cosmic microwave background anisotropies provide a vast amount of information on both structure formation in the universe and the background dynamics and geometry. The full physical content and detailed structure of anisotropies can be…

Astrophysics · Physics 2018-01-29 Wayne Hu , Naoshi Sugiyama , Joseph Silk

We provide a new derivation of the anisotropies of the cosmic microwave background (CMB), and find an exact expression that can be readily expanded perturbatively. Close attention is paid to gauge issues, with the motivation to examine the…

Astrophysics · Physics 2009-01-08 J. P. Zibin , Douglas Scott

We give a brief review of the physics of acoustic oscillations in Cosmic Microwave Background (CMB) anisotropies. As an example of the impact of their detection in cosmology, we show how the present data on CMB angular power spectrum on…

Astrophysics · Physics 2015-06-24 C. Baccigalupi , A. Balbi , S. Matarrese , F. Perrotta , N. Vittorio

The cosmic microwave background (CMB) contains perturbations that are close to Gaussian and isotropic. This means that its information content, in the sense of the ability to constrain cosmological models, is closely related to the number…

Cosmology and Nongalactic Astrophysics · Physics 2016-07-06 Douglas Scott , Dagoberto Contreras , Ali Narimani , Yin-Zhe Ma

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

The cosmological principle asserts that the Universe is homogeneous and isotropic on large enough scales. However, alternative cosmological models can bring about anisotropies through local inhomogeneities, anisotropic evolution, or exotic…

The anisotropy of the cosmic microwave background radiation contains information about the contents and history of the universe. We report new limits on cosmological parameters derived from the angular power spectrum measured in the first…

The Cosmic Background Radiation gives us one of the few probes into the density perturbations in the early universe that should later lead to the formation of structure we now observe. Recent advances in degree scale anisotropy measurements…

Astrophysics · Physics 2007-05-23 P. M. Lubin

Low amplitude (linear regime) cosmic density fluctuations lead to spatial variations in the locally measurable value of $H_0$ (denoted as $H_L$), $\delta_H \equiv (H_L-H_0)/H_0$, which are of order 3-6% (95% confidence interval) in a sphere…

Astrophysics · Physics 2009-10-30 Yun Wang , David N. Spergel , Edwin L. Turner

The blackbody radiation left over from the Big Bang has been transformed by the expansion of the Universe into the nearly isotropic 2.73K Cosmic Microwave Background. Tiny inhomogeneities in the early Universe left their imprint on the…

We perform a joint likelihood analysis of the power spectra of the 2dF Galaxy Redshift Survey (2dFGRS) and the cosmic microwave background (CMB) anisotropies under the assumptions that the initial fluctuations were adiabatic, Gaussian and…

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