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An extremely cold and big spot in the WMAP 1-year data is analyzed. Our work is a continuation of a previous paper (Vielva et al. 2004) where non-Gaussianity was detected, with a method based on the Spherical Mexican Hat Wavelet (SMHW)…

天体物理学 · 物理学 2009-07-09 M. Cruz , E. Martinez-Gonzalez , P. Vielva , L. Cayon

We present theoretical and observational studies of non-Gaussian fluctuations in CMB, by using the angular bispectrum and trispectrum. We predict the primary angular bispectrum from inflation, and forecast how well we can measure the…

天体物理学 · 物理学 2007-05-23 Eiichiro Komatsu

We present a novel approach to estimate the value of primordial non-Gaussianity ($f_{\rm NL}$) parameter directly from the Cosmic Microwave Background (CMB) maps using a convolutional neural network (CNN). While traditional methods rely on…

宇宙学与河外天体物理 · 物理学 2024-03-26 Chandan G. Nagarajappa , Yin-Zhe Ma

The extensive search for deviations from Gaussianity in cosmic microwave background radiation (CMB) data is very important due to the information about the very early moments of the universe encoded there. Recent analyses from Planck CMB…

宇宙学与河外天体物理 · 物理学 2015-06-18 C. P. Novaes , A. Bernui , I. S. Ferreira , C. A. Wuensche

Secondary contributions to the anisotropy of the Cosmic Microwave Background (CMB), such as the integrated Sachs-Wolfe (ISW) effect, the thermal Sunyaev-Zel'dovich effect (tSZ), and the effect of gravitational lensing, have distinctive…

宇宙学与河外天体物理 · 物理学 2012-07-27 Dipak Munshi , Peter Coles , Alan Heavens

Point-source contamination in high-precision Cosmic Microwave Background (CMB) maps severely affects the precision of cosmological parameter estimates. Among the methods that have been proposed for source detection, wavelet techniques based…

天体物理学 · 物理学 2009-11-07 R. Vio , L. Tenorio , W. Wamsteker

The trispectrum of the cosmic microwave background can be used to assess the level of non-Gaussianity on cosmological scales. It probes the fourth order moment, as a function of angular scale, of the probability distribution function of…

We present a new, model-independent approach for measuring non-Gaussianity of the Cosmic Microwave Background (CMB) anisotropy pattern. Our approach is based on the empirical distribution function of the normalized spherical harmonic…

天体物理学 · 物理学 2011-05-10 Frode K. Hansen , Domenico Marinucci , Paolo Natoli , Nicola Vittorio

An analysis of the sensitivity of gaussian and mexican hat wavelet family filters to the detection of point sources of ultra-high energy cosmic rays was performed. A source embedded in a background was simulated and the number of events and…

天体物理仪器与方法 · 物理学 2012-03-26 Rafael Alves Batista , Ernesto Kemp , Bruno Daniel

In this article we consider the detection of compact sources in maps of the Cosmic Microwave Background radiation (CMB) following the philosophy behind the Mexican Hat Wavelet Family (MHWn) of linear filters. We present a new analytical…

宇宙学与河外天体物理 · 物理学 2015-06-03 M. López-Caniego , P. Vielva

We present a new method to estimate three-point correlations in Cosmic Microwave Background maps. Our Fast Fourier Transform based implementation estimates three-point functions using all possible configurations (triangles) at a controlled…

天体物理学 · 物理学 2009-11-13 Gang Chen , Istvan Szapudi

The cosmic microwave background (CMB) is a relic radiation of the Big Bang and as such it contains a wealth of cosmological information. Statistical analyses of the CMB, in conjunction with other cosmological observables, represent some of…

Minimum-variance estimators for the parameter fnl that quantifies local-model non-Gaussianity can be constructed from the cosmic microwave background (CMB) bispectrum (three-point function) and also from the trispectrum (four-point…

宇宙学与河外天体物理 · 物理学 2011-02-03 Marc Kamionkowski , Tristan L. Smith , Alan Heavens

We test the consistency of estimates of the non-linear coupling constant f_{NL} using non-Gaussian CMB maps generated by the method described in (Liguori, Matarrese and Moscardini 2003). This procedure to obtain non-Gaussian maps differs…

天体物理学 · 物理学 2009-11-10 P. Cabella , M. Liguori , F. K. Hansen , D. Marinucci , S. Matarrese , L. Moscardini , N. Vittorio

We present a new method based on the N-point probability distribution (pdf) to study non-Gaussianity in cosmic microwave background (CMB) maps. Likelihood and Bayesian estimation are applied to a local non-linear perturbed model up to third…

天体物理学 · 物理学 2015-05-13 P. Vielva , J. L. Sanz

We investigate the cosmological information in higher-order statistics of the cosmic microwave background (CMB) lensing convergence field for a near-term experiment with noise properties similar to the Simons Observatory (SO). Using a fully…

宇宙学与河外天体物理 · 物理学 2026-03-16 Shu-Fan Chen , J. Colin Hill , Zoltán Haiman

We develop optimised estimators of two sorts of power spectra for fields defined on the sky, in the presence of partial sky coverage. The first is the cross-power spectrum of two fields on the sky; the second is the skew spectrum of three…

宇宙学与河外天体物理 · 物理学 2015-05-13 Dipak Munshi , Patrick Valageas , Asantha Cooray , Alan Heavens

Extracting sources with low signal-to-noise from maps with structured background is a non-trivial task which has become important in studying the faint end of the submillimetre number counts. In this article we study source extraction from…

We explore a systematic approach to the analysis of primordial non-Gaussianity using fluctuations in temperature and polarization of the Cosmic Microwave Background (CMB). Following Munshi & Heavens (2009), we define a set of power-spectra…

宇宙学与河外天体物理 · 物理学 2015-05-18 Dipak Munshi , Peter Coles , Asantha Cooray , Alan Heavens , Joseph Smidt

Since the inhomogeneous instrument noise can produce extra non-Gaussianity in the CMB anisotropy, its effect should be carefully subtracted in the primordial non-Gaussianity estimation. We calculate the probability distribution function of…

天体物理学 · 物理学 2009-02-23 B. Yu , T. Lu