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The fluctuations of the cosmic microwave background (CMB) are investigated for a hyperbolic universe with finite volume. Four-component models with radiation, matter, vacuum energy, and an extra spatially constant dark energy X-component…

Astrophysics · Physics 2015-06-24 R. Aurich , F. Steiner

We present a new estimate of foreground emission in the WMAP data, using a Markov chain Monte Carlo (MCMC) method. The new technique delivers maps of each foreground component for a variety of foreground models, error estimates of the…

The Cosmological Principle, which states that the Universe is homogeneous and isotropic (when averaged on large scales), is the foundational assumption of Friedmann-Lemaitre-Robertson-Walker (FLRW) cosmologies such as the current standard…

Cosmology and Nongalactic Astrophysics · Physics 2025-12-15 Nathan Secrest , Sebastian von Hausegger , Mohamed Rameez , Roya Mohayaee , Subir Sarkar

We investigate a corner of the Bianchi models that has not received much attention: "extended FLRW models" (eFLRW) defined as a cosmological model with underlying anisotropic Bianchi geometry that nevertheless expands isotropically and can…

General Relativity and Quantum Cosmology · Physics 2020-02-21 Mikjel Thorsrud , Ben D. Normann , Thiago S. Pereira

We present the temperature and polarization angular power spectra of the cosmic microwave background (CMB) derived from the first 5 years of WMAP data. The 5-year temperature (TT) spectrum is cosmic variance limited up to multipole l=530,…

Massive bigravity models are interesting alternatives to standard cosmology. In most cases, however, these models have been studied for a simplified scenario in which both metrics take homogeneous and isotropic forms…

General Relativity and Quantum Cosmology · Physics 2015-11-18 Henrik Nersisyan , Yashar Akrami , Luca Amendola

Recent Wilkinson Microwave Anisotropy Probe (WMAP) data confirm the Cosmic Microwave Background (CMB) quadrupole anomaly. We further elaborate our previous proposal that the quadrupole power can be naturally suppressed in axis-symmetric…

Astrophysics · Physics 2008-11-26 L. Campanelli , P. Cea , L. Tedesco

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 Friedmann-Robertson-Walker (FRW) universe and Bianchi I,II universes are investigated in the framework of the generalized uncertainty principle (GUP) with a linear and a quadratic term in Planck length and momentum, which predicts…

General Relativity and Quantum Cosmology · Physics 2014-10-21 Ahmed Farag Ali , Barun Majumder

Motivated by the isotropy of the CMB spectrum, all existing studies of magnetised cosmological perturbations employ FRW backgrounds. However, it is important, to know the limits of this approximation and the effects one loses by neglecting…

General Relativity and Quantum Cosmology · Physics 2009-10-31 Christos Tsagas , Roy Maartens

We investigate anomalies reported in the Cosmic Microwave Background maps from the Wilkinson Microwave Anisotropy Probe (WMAP) satellite on very large angular scales and discuss possible interpretations. Three independent anomalies involve…

The Wilkinson Microwave Anisotropy Probe (WMAP) has measured lower amplitudes for the temperature quadrupole and octopole anisotropies than expected in the best fitting (concordance) Lambda-dominated cold dark matter cosmology. Some authors…

Astrophysics · Physics 2009-11-10 G. Efstathiou

WMAP precision data enables accurate testing of cosmological models. We find that the emerging standard model of cosmology, a flat Lambda-dominated universe seeded by nearly scale-invariant adiabatic Gaussian fluctuations, fits the WMAP…

The Ehlers-Ellis 1+3 formulation of covariant hydrodynamics, when supplemented with covariant radiative transport theory, gives an exact, physically transparent description of the physics of the cosmic microwave background radiation (CMB).…

Astrophysics · Physics 2015-06-24 Anthony Challinor

We investigate in detail some popular cosmological models in light of the latest observational data, including the Union2.1 supernovae compilation, the baryon acoustic oscillation measurements from the WiggleZ Dark Energy Survey, the cosmic…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-05 Ke Shi , Yongfeng Huang , Tan Lu

The Wilkinson Microwave Anisotropy Probe (WMAP) science team has released results from the first year of operation at the Earth-Sun L2 Lagrange point. The maps are consistent with previous observations but have much better sensitivity and…

Astrophysics · Physics 2007-05-23 E. L. Wright

This study explores the compatibility of Covariant Extrinsic Gravity (CEG) with current cosmological observations. We employ the chi-square statistic and Markov Chain Monte Carlo (MCMC) methods to fit the FLRW and Bianchi type-I and V brane…

General Relativity and Quantum Cosmology · Physics 2024-07-23 R. Jalalzadeh , S. Jalalzadeh , B. Malekolkalami , Z. Davari

It has generally been thought that in perturbed Friedmann-Lemaitre-Robertson-Walker models of the Universe, global topology should not have any feedback effects on dynamics. However, a weak-field limit heuristical argument, assuming a…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-20 Boudewijn F. Roukema

The oscillating scenario of route to Lambda was recently proposed by us arXiv:0704.1651 as an alternative to a cosmological constant in a explanation of the current accelerating universe. In this scenario phantom scalar field conformally…

Astrophysics · Physics 2008-11-26 Aleksandra Kurek , Orest Hrycyna , Marek Szydlowski

The recent announcement from the Wilkinson Microwave Anisotropy Probe (WMAP) satellite experiment combined with other recent advances in observational cosmology verifies key components of the standard cosmological model. However, we argue…

Astrophysics · Physics 2009-09-15 Sarah L. Bridle , Ofer Lahav , Jeremiah P. Ostriker , Paul J. Steinhardt