Evidence of Primordial Non-Gaussianity (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>f</mml:mi><mml:mi>NL</mml:mi></mml:msub></mml:math>) in the Wilkinson Microwave Anisotropy Probe 3-Year Data at<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mn>2.8</mml:mn><mml:mi>σ</mml:mi></mml:math>

Yadav, Amit; Wandelt, B. D.

doi:10.1103/physrevlett.100.181301

Cited by 229 publications

(326 citation statements)

References 35 publications

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“…[207,208]. Recently, there has been the claim of a detection of such non-Gaussianities by Yadav and Wandelt [209] and a confirmation of this with better data and improved algorithms is therefore highly desirable. In Sect.…”

Section: Cosmic Microwave Backgroundmentioning

confidence: 99%

Information field theory for cosmological perturbation reconstruction and nonlinear signal analysis

2009

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We develop information field theory (IFT) as a means of Bayesian inference on spatially distributed signals, the information fields. A didactical approach is attempted. Starting from general considerations on the nature of measurements, signals, noise, and their relation to a physical reality, we derive the information Hamiltonian, the source field, propagator, and interaction terms. Free IFT reproduces the well known Wiener-filter theory. Interacting IFT can be diagrammatically expanded, for which we provide the Feynman rules in position-, Fourier-, and spherical harmonics space, and the Boltzmann-Shannon information measure. The theory should be applicable in many fields. However, here, two cosmological signal recovery problems are discussed in their IFTformulation. 1) Reconstruction of the cosmic large-scale structure matter distribution from discrete galaxy counts in incomplete galaxy surveys within a simple model of galaxy formation. We show that a Gaussian signal, which should resemble the initial density perturbations of the Universe, observed with a strongly non-linear, incomplete and Poissonian-noise affected response, as the processes of structure and galaxy formation and observations provide, can be reconstructed thanks to the virtue of a response-renormalization flow equation. 2) We design a filter to detect local non-linearities in the cosmic microwave background, which are predicted from some Early-Universe inflationary scenarios, and expected due to measurement imperfections. This filter is the optimal Bayes' estimator up to linear order in the non-linearity parameter and can be used even to construct sky maps of non-linearities in the data.

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Section: Cosmic Microwave Backgroundmentioning

confidence: 99%

Information field theory for cosmological perturbation reconstruction and nonlinear signal analysis

2009

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“…Current limits from the CMB/LSS are in the ballpark of |f nl | 100 [9,10]. The plot has thickened with a suggestion [11] (not universally accepted) that the WMAP 3-year data prefers (at the 2.8σ level) f nl = 0, with a best-fit value f nl 80 (a less significant result of 1.5σ is found in an analysis of the most recent WMAP data release [9]). The Planck satellite [12] is expected to achieve a sensitivity of f nl ∼ 5.…”

Section: Introductionmentioning

confidence: 99%

Probability distribution for non-Gaussianity estimators

2011

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One of the principle efforts in cosmic microwave background (CMB) research is measurement of the parameter f nl that quantifies the departure from Gaussianity in a large class of non-minimal inflationary (and other) models. Estimators for f nl are composed of a sum of products of the temperatures in three different pixels in the CMB map. Since the number ∼ N 2 pix of terms in this sum exceeds the number Npix of measurements, these ∼ N 2 pix terms cannot be statistically independent. Therefore, the central-limit theorem does not necessarily apply, and the probability distribution function (PDF) for the f nl estimator does not necessarily approach a Gaussian distribution for Npix 1. Although the variance of the estimators is known, the significance of a measurement of f nl depends on knowledge of the full shape of its PDF. Here we use Monte Carlo realizations of CMB maps to determine the PDF for two minimum-variance estimators: the standard estimator, constructed under the null hypothesis (f nl = 0), and an improved estimator with a smaller variance for f nl = 0. While the PDF for the null-hypothesis estimator is very nearly Gaussian when the true value of f nl is zero, the PDF becomes significantly non-Gaussian when f nl = 0. In this case we find that the PDF for the null-hypothesis estimator f nl is skewed, with a long non-Gaussian tail at f nl > |f nl | and less probability at f nl < |f nl | than in the Gaussian case. We provide an analytic fit to these PDFs. On the other hand, we find that the PDF for the improved estimator is nearly Gaussian for observationally allowed values of f nl . We discuss briefly the implications for trispectrum (and other higher-order correlation) estimators.

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“…Thus energy density of the gravitino fluctuates in the same way as that of the inflaton, so does the LSP directly created by the gravitino decay. 8 Thus those nonthermal LSPs have (correlated) isocurvature perturbations. This is exactly the case of Sec.…”

Section: A 'Realistic' Examplementioning

confidence: 99%

A general analysis of non-gaussianity from isocurvature perturbations

Kawasaki

Nakayama

Sekiguchi

et al. 2009

J. Cosmol. Astropart. Phys.

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Light scalars may be ubiquitous in nature, and their quantum fluctuations can produce large non-Gaussianity in the cosmic microwave background temperature anisotropy. The non-Gaussianity may be accompanied with a small admixture of isocurvature perturbations, which often have correlations with the curvature perturbations. We present a general method to calculate the non-Gaussianity in the adiabatic and isocurvature perturbations with and without correlations, and see how it works in several explicit examples. We also show that they leave distinct signatures on the bispectrum of the cosmic microwave background temperature fluctuations.

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Evidence of Primordial Non-Gaussianity (fNL) in the Wilkinson Microwave Anisotropy Probe 3-Year Data at2.8σ

Cited by 229 publications

References 35 publications

Information field theory for cosmological perturbation reconstruction and nonlinear signal analysis

Information field theory for cosmological perturbation reconstruction and nonlinear signal analysis

Probability distribution for non-Gaussianity estimators

A general analysis of non-gaussianity from isocurvature perturbations

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