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Recently, BICEP2 measurements of the cosmic microwave background (CMB) $B$-mode polarization has indicated the presence of primordial gravitational waves at degree angular scales, inferring the tensor-to-scalar ratio of $r=0.2$ and a…

Cosmology and Nongalactic Astrophysics · Physics 2018-06-11 Seokcheon Lee , Guo-Chin Liu , Kin-Wang Ng

The cosmic microwave background (CMB) temperature anisotropies exhibit a large-scale dipolar power asymmetry. To determine whether this is due to a real, physical modulation or is simply a large statistical fluctuation requires the…

Cosmology and Nongalactic Astrophysics · Physics 2018-02-07 D. Contreras , J. P. Zibin , D. Scott , A. J. Banday , K. M. Górski

The cosmic microwave background (CMB) anisotropies have turned out to represent one of the most stringent 'bottle necks' for scenarios of large scale structure formation. As a possibility to relax this constraint, it has been proposed that…

Astrophysics · Physics 2009-10-22 Ruth Durrer

A large-scale temperature perturbation has a non-zero correlation with the power spectrum of B-modes of cosmological origin on short scales while the corresponding correlation is expected to be zero for B-modes sourced by galactic…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-22 A. Kehagias , A. Moradinezhad-Dizgah , J. Noreña , H. Perrier , A. Riotto

The BICEP2 collaboration has reported a strong B mode signal in the CMB polarization, which is well fit by a tensor-to-scalar ratio of r ~ 0.2. This is greater than the upper limit r < 0.11 obtained from the temperature anisotropies under…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-19 Carlo R. Contaldi , Marco Peloso , Lorenzo Sorbo

At wavelengths longer than 21 cm, photons from the long-wavelength tail of the cosmic microwave background (CMB) have a non-zero probability of being absorbed by distant neutral hydrogen. This provides an additional suppression of the…

Cosmology and Nongalactic Astrophysics · Physics 2026-05-25 Gilbert Holder , Adrian Liu , Tzu-Ching Chang , David Zegeye

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

The measurement of the brightness temperature fluctuations of neutral hydrogen 21 cm lines from the Epoch of Reionisation (EoR) is expected to be a powerful tool for revealing the reionisation process. We study the 21 cm cross-correlation…

Cosmology and Nongalactic Astrophysics · Physics 2011-04-07 Hiroyuki Tashiro , Nabila Aghanim , Mathieu Langer , Marian Douspis , Saleem Zaroubi , Vibor Jelic

One of the main goals of Cosmology is to search for the imprint of primordial gravitational waves in the CMB polarisation field, to probe inflationary theories. One of the obstacles toward the detection of the primordial signal is to…

Cosmology and Nongalactic Astrophysics · Physics 2020-10-28 G. Lagache , M. Bethermin , L. Montier , P. Serra , M. Tucci

The scalar mode temperature fluctuations of the cosmic microwave background has been derived in a spatially closed universe from two different methods. First, by following the photon trajectory after the last scattering and then from the…

General Relativity and Quantum Cosmology · Physics 2017-09-27 Pedram Niazy , Amir H. Abbassi

A ground-based polarimeter, PIQUE, operating at 90 GHz has set a new limit on the magnitude of any polarized anisotropy in the cosmic microwave background. The combination of the scan strategy and full width half maximum beam of 0.235…

Astrophysics · Physics 2009-10-31 M. M. Hedman , D. Barkats , J. O. Gundersen , S. T. Staggs , B. Winstein

The low quadrupole of the cosmic microwave background (CMB), measured by COBE and confirmed by WMAP, has generated much discussion recently. We point out that the well-known correlation between temperature and polarization anisotropies of…

Astrophysics · Physics 2009-06-15 Olivier Doré , Gilbert P. Holder , Abraham Loeb

The search for primordial $B$-mode polarization of the CMB is limited by the sample variance of $B$-modes produced at later times by gravitational lensing. Constraints can be improved by `delensing': using some proxy of the matter…

Cosmology and Nongalactic Astrophysics · Physics 2023-01-24 Antón Baleato Lizancos , Simone Ferraro

Weak gravitational lensing by the intervening large-scale structure of the Universe induces high-order correlations in the cosmic microwave background (CMB) temperature and polarization fields. We construct minimum variance estimators of…

Astrophysics · Physics 2008-11-26 Wayne Hu , Takemi Okamoto

We investigate which practical constraints are imposed by foregrounds to the detection of the B-mode polarization generated by gravitational waves in the case of experiments of the type currently being planned. Because the B-mode signal is…

Astrophysics · Physics 2009-11-10 M. Tucci , E. Martinez-Gonzalez , P. Vielva , J. Delabrouille

Motivated by WMAP's confirmation of an anomalously low value of the quadrupole moment of the CMB temperature fluctuations, we investigate the effects on the CMB of cutting off the primordial power spectrum P(k) at low wave numbers. This…

Astrophysics · Physics 2009-11-07 James M. Cline , Patrick Crotty , Julien Lesgourgues

In the frame of a moving observer, the Cosmic Microwave Background (CMB) fluctuation exhibits violation of Statistical Isotropy (SI). The SI violation effect from our local motion on CMB temperature fluctuation has been measured in the…

Cosmology and Nongalactic Astrophysics · Physics 2015-04-27 Suvodip Mukherjee , Aritra De , Tarun Souradeep