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We introduce an exact Bayesian approach to search for non-Gaussianity of local type in Cosmic Microwave Background (CMB) radiation data. Using simulated CMB temperature maps, the newly developed technique is compared against the…

Cosmology and Nongalactic Astrophysics · Physics 2010-11-15 Franz Elsner , Benjamin D. Wandelt

Gaussian random fields play an important role in many areas of science and engineering. In practice, they are often simulated by sampling from a high-dimensional multivariate normal distribution, which arises from the discretisation of a…

Numerical Analysis · Mathematics 2026-02-12 Yoshihito Kazashi , Eike H. Müller , Robert Scheichl

We present an efficient implementation of Wiener filtering of real-space linear field and optimal quadratic estimator of its power spectrum Band-powers. We first recast the field reconstruction into an optimization problem, which we solve…

Cosmology and Nongalactic Astrophysics · Physics 2019-10-16 Benjamin Horowitz , Uros Seljak , Grigor Aslanyan

We propose a novel framework for joint magnetic resonance image reconstruction and uncertainty quantification using under-sampled k-space measurements. The problem is formulated as a Bayesian linear inverse problem, where prior…

Image and Video Processing · Electrical Eng. & Systems 2026-03-17 Ahmed Karam Eldaly , Matteo Figini , Daniel C. Alexander

We describe a Bayesian framework for estimating the time-domain noise covariance of CMB observations, typically parametrized in terms of a 1/f frequency profile. This framework is based on the Gibbs sampling algorithm, which allows for…

Instrumentation and Methods for Astrophysics · Physics 2015-05-30 I. K. Wehus , S. K. Næss , H. K. Eriksen

Estimating the cosmological microwave background is of utmost importance for cosmology. However, its estimation from full-sky surveys such as WMAP or more recently Planck is challenging: CMB maps are generally estimated via the application…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-03 J. Bobin , J. -L. Starck , F. Sureau , J. Fadili

Optimal extraction of cosmological information from observations of the Cosmic Microwave Background critically relies on our ability to accurately undo the distortions caused by weak gravitational lensing. In this work, we demonstrate the…

Cosmology and Nongalactic Astrophysics · Physics 2024-06-07 Thomas Flöss , William R. Coulton , Adriaan J. Duivenvoorden , Francisco Villaescusa-Navarro , Benjamin D. Wandelt

Convolutional sparse coding (CSC) can learn representative shift-invariant patterns from multiple kinds of data. However, existing CSC methods can only model noises from Gaussian distribution, which is restrictive and unrealistic. In this…

Machine Learning · Computer Science 2020-04-22 Yaqing Wang , James T. Kwok , Lionel M. Ni

In magnetoencephalography (MEG) the conventional approach to source reconstruction is to solve the underdetermined inverse problem independently over time and space. Here we present how the conventional approach can be extended by…

We consider a cosmological model with non-Gaussian initial perturbations, which in principle could be generated in non-standard inflationary scenarios with two or more scalar fields. In particular we focus our attention on the model…

Astrophysics · Physics 2011-05-10 Dmitri Novikov , Jens Schmalzing , Viatcheslav F. Mukhanov

The accurate reconstruction of Cosmic Microwave Background (CMB) maps and the measurement of its power spectrum are crucial for studying the early universe. In this paper, we implement a convolutional neural network to apply the Wiener…

Cosmology and Nongalactic Astrophysics · Physics 2024-06-07 Belén Costanza , Claudia G. Scóccola , Matías Zaldarriaga

To efficiently probe primordial non-Gaussianity using Cosmic Microwave Background (CMB) data, we require theoretical predictions that are factorizable, \textit{i.e.}\ those whose kinematic dependence can be separated. This property does not…

Cosmology and Nongalactic Astrophysics · Physics 2025-11-25 Oliver H. E. Philcox , Kunhao Zhong , Salvatore Samuele Sirletti

Gaussian processes are a fully Bayesian smoothing technique that allows for the reconstruction of a function and its derivatives directly from observational data, without assuming a specific model or choosing a parameterization. This is…

Cosmology and Nongalactic Astrophysics · Physics 2013-11-27 Marina Seikel , Chris Clarkson

In this work we propose a new matrix-free implementation of the Wiener sampler which is traditionally applied to high dimensional analysis when signal covariances are unknown. Specifically, the proposed method addresses the problem of…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-18 Jens Jasche , Guilhem Lavaux

The presence of astrophysical emissions in microwave observations forces us to perform component separation to extract the Cosmic Microwave Background (CMB) signal. However, even in the most optimistic cases, there are still strongly…

Cosmology and Nongalactic Astrophysics · Physics 2024-09-26 C. Gimeno-Amo , E. Martínez-González , R. B. Barreiro

Solving Bayesian inference problems approximately with variational approaches can provide fast and accurate results. Capturing correlation within the approximation requires an explicit parametrization. This intrinsically limits this…

Machine Learning · Statistics 2020-01-31 Jakob Knollmüller , Torsten A. Enßlin

We propose an efficient and model independent method for reconstructing the primordial power spectrum from Cosmic Microwave Background (CMB) and large scale structure observations. The algorithm is based on a Monte Carlo principle and…

Astrophysics · Physics 2009-11-10 Steen Hannestad

The cosmic microwave background (CMB), carrying the inhomogeneous information of the very early universe, is of great significance for understanding the origin and evolution of our universe. However, observational CMB maps contain serious…

Cosmology and Nongalactic Astrophysics · Physics 2022-05-12 Guo-Jian Wang , Hong-Liang Shi , Ye-Peng Yan , Jun-Qing Xia , Yan-Yun Zhao , Si-Yu Li , Jun-Feng Li

The Quadratic Maximum Likelihood estimator can be used to reconstruct the Cosmic Microwave Background (CMB) power spectra with minimal error bars. Still, it requires an accurate estimate of the datasets noise covariance matrix in order to…

Cosmology and Nongalactic Astrophysics · Physics 2018-11-28 S. Vanneste , S. Henrot-Versillé , T. Louis , M. Tristram

We present a new blind formulation of the Cosmic Microwave Background (CMB) inference problem. The approach relies on a phenomenological model of the multi-frequency microwave sky without the need for physical models of the individual…

Cosmology and Nongalactic Astrophysics · Physics 2016-03-30 Flavien Vansyngel , Benjamin D. Wandelt , Jean-François Cardoso , Karim Benabed