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We use quadratic maximum-likelihood (QML) estimators to constrain models with Gaussian but statistically anisotropic Cosmic Microwave Background (CMB) fluctuations, using CMB maps with realistic sky-coverage and instrumental noise. This…

宇宙学与河外天体物理 · 物理学 2012-03-06 Duncan Hanson , Antony Lewis

Over the last decade, measurements of the CMB anisotropy has spearheaded the remarkable transition of cosmology into a precision science. However, addressing the systematic effects in the increasingly sensitive, high resolution, `full' sky…

天体物理学 · 物理学 2009-03-31 Sanjit Mitra , Anand S. Sengupta , Subharthi Ray , Rajib Saha , Tarun Souradeep

The majority of present efforts to constrain cosmological parameters with cosmic microwave background (CMB) anisotropy data employ approximate likelihood functions, the time consuming nature of a complete analysis being a major obstacle. We…

天体物理学 · 物理学 2007-05-23 M. Douspis , J. G. Bartlett , A. Blanchard , M. Le Dour

Obscuration due to Galactic emission complicates the extraction of information from cosmological surveys, and requires some combination of the (typically imperfect) modeling and subtraction of foregrounds, or the removal of part of the sky.…

宇宙学与河外天体物理 · 物理学 2011-11-14 Stephen M. Feeney , Hiranya V. Peiris , Andrew Pontzen

The presence of astrophysical emissions between the last scattering surface and our vantage point requires us to apply a foreground mask on CMB sky map, leading to large cut around the Galactic equator and numerous holes. Since many CMB…

宇宙学与河外天体物理 · 物理学 2012-04-17 Jaiseung Kim , Pavel Naselsky , Nazzareno Mandolesi

We discuss an approach to the component separation of microwave, multi-frequency sky maps as those typically produced from Cosmic Microwave Background (CMB) Anisotropy data sets. The algorithm is based on the two step, parametric,…

天体物理学 · 物理学 2009-06-23 R. Stompor , S. Leach , F. Stivoli , C. Baccigalupi

Most parameter constraints obtained from cosmic microwave background (CMB) anisotropy data are based on power estimates and rely on approximate likelihood functions; computational difficulties generally preclude an exact analysis based on…

天体物理学 · 物理学 2009-11-06 M. Douspis , J. G. Bartlett , A. Blanchard , M. Le Dour

It is widely believed that maximum likelihood estimators must be used to provide optimal estimates of power spectra. Since such estimators require require of order N_d^3 operations they are computationally prohibitive for N_d greater than a…

天体物理学 · 物理学 2008-11-26 G. Efstathiou

We develop a new method for reconstructing cluster mass profiles and large-scale structure from the cosmic microwave background (CMB). By analyzing the likelihood of CMB lensing, we analytically prove that standard quadratic estimators for…

天体物理学 · 物理学 2008-11-26 Jaiyul Yoo , Matias Zaldarriaga

Much attention has been given to the problem of estimating cosmological parameters from the $C_l$ measured by future experiments. Many of the approaches which are being used either invoke poorly controlled approximations or are…

天体物理学 · 物理学 2007-05-23 Benjamin D. Wandelt , Eric Hivon , Krzysztof M. Gorski

We describe our methodology for comparing the WMAP measurements of the cosmic microwave background (CMB) and other complementary data sets to theoretical models. The unprecedented quality of the WMAP data, and the tight constraints on…

In the context of cosmic microwave background (CMB) data analysis, we compare the efficiency at large scale of two angular power spectrum algorithms, implementing, respectively, the quadratic maximum likelihood (QML) estimator and the…

宇宙学与河外天体物理 · 物理学 2015-06-19 Diego Molinari , Alessandro Gruppuso , Gianluca Polenta , Carlo Burigana , Adriano De Rosa , Paolo Natoli , Fabio Finelli , Francesco Paci

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,…

Upcoming ground-based cosmic microwave background experiments will provide CMB maps with high sensitivity and resolution that can be used for high fidelity lensing reconstruction. However, the sky coverage will be incomplete and the noise…

宇宙学与河外天体物理 · 物理学 2019-12-11 Mark Mirmelstein , Julien Carron , Antony Lewis

We revisit the problem of exact CMB likelihood and power spectrum estimation with the goal of minimizing computational cost through linear compression. This idea was originally proposed for CMB purposes by Tegmark et al.\ (1997), and here…

天体物理仪器与方法 · 物理学 2015-11-18 E. Gjerløw , L. P. L. Colombo , H. K. Eriksen , K. M. Górski , A. Gruppuso , J. B. Jewell , S. Plaszczynski , I. K. Wehus

We constrain several models of the early Universe that predict a statistical anisotropy of the cosmic microwave background (CMB) sky. We make use of WMAP9 maps deconvolved with beam asymmetries. As compared to previous releases of WMAP…

宇宙学与河外天体物理 · 物理学 2014-03-03 Sabir Ramazanov , Grigory Rubtsov

We describe the calibration and data processing methods used to generate full-sky maps of the cosmic microwave background (CMB) from the first year of Wilkinson Microwave Anisotropy Probe (WMAP) observations. Detailed limits on residual…

The CMB maps obtained by observations always possess domains which have to be masked due to severe uncertainties with respect to the genuine CMB signal. Cosmological analyses ideally use full CMB maps in order to get e.g. the angular power…

宇宙学与河外天体物理 · 物理学 2015-05-19 R. Aurich , S. Lustig

Accurate estimation of the Cosmic Microwave Background (CMB) angular power spectrum is enticing due to the prospect for precision cosmology it presents. Galactic foreground emissions, however, contaminate the CMB signal and need to be…

宇宙学与河外天体物理 · 物理学 2021-10-04 Pallav Chanda , Rajib Saha

Recent analyses of the WMAP data seem to indicate the possible presence of large-angle anisotropy in the Universe. If confirmed, these can have important consequences for our understanding of the Universe. A number of attempts have recently…

天体物理学 · 物理学 2009-06-23 A. Bernui , B. Mota , M. J. Reboucas , R. Tavakol
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