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In this chapter, we give a brief introduction into the use of the Zeeman effect in astronomy and the general detection of magnetic fields in stars, concentrating on the use of FORS2 for longitudinal magnetic field measurements.

Solar and Stellar Astrophysics · Physics 2015-01-20 Markus Schöller , Swetlana Hubrig

We present a theory for the estimation of a scalar or a vector magnetic field by its influence on an ensemble of trapped spin polarized atoms. The atoms interact off-resonantly with a continuous laser field, and the measurement of the…

Quantum Physics · Physics 2009-11-10 Vivi Petersen , Lars Bojer Madsen , Klaus Molmer

Bayesian analysis has become an indispensable tool across many different cosmological fields including the study of gravitational waves, the Cosmic Microwave Background and the 21-cm signal from the Cosmic Dawn among other phenomena. The…

Instrumentation and Methods for Astrophysics · Physics 2023-12-19 Harry T. J. Bevins , William J. Handley , Pablo Lemos , Peter H. Sims , Eloy de Lera Acedo , Anastasia Fialkov , Justin Alsing

In Bayesian statistics, one's prior beliefs about underlying model parameters are revised with the information content of observed data from which, using Bayes' rule, a posterior belief is obtained. A non-trivial example taken from the…

High Energy Physics - Phenomenology · Physics 2007-05-23 J. Charles , A. Hocker , H. Lacker , F. R. Le Diberder , S. T'Jampens

We present preliminary results from a programme aimed at acquiring linear spectropolarimetry of magnetic A and B stars. Linear polarization in the spectral lines of these objects is due to the Zeeman effect, and should provide detailed new…

Astrophysics · Physics 2016-08-30 G. A. Wade , J. -F. Donati , G. Mathys , N. Piskunov

Variational Bayesian Inference is a popular methodology for approximating posterior distributions over Bayesian neural network weights. Recent work developing this class of methods has explored ever richer parameterizations of the…

We study the application of a Bayesian method to extract relevant information from data for the case of a signal consisting of two or more decaying particles and its background. The method takes advantage of the dependence that exists in…

High Energy Physics - Phenomenology · Physics 2023-06-06 Ezequiel Alvarez

Detecting and measuring a non-Gaussian signature of primordial origin in the density field is a major science goal of next-generation galaxy surveys. The signal will permit us to determine primordial physics processes and constrain models…

Cosmology and Nongalactic Astrophysics · Physics 2023-02-15 Adam Andrews , Jens Jasche , Guilhem Lavaux , Fabian Schmidt

Determining magnetic field properties in different environments of the cosmic large-scale structure as well as their evolution over redshift is a fundamental step toward uncovering the origin of cosmic magnetic fields. Radio observations…

Implicit particle filtering is a sequential Monte Carlo method for data assim- ilation, designed to keep the number of particles manageable by focussing attention on regions of large probability. These regions are found by min- imizing, for…

Numerical Analysis · Mathematics 2015-05-30 Matthias Morzfeld , Alexandre J. Chorin

Magnetic nanoparticles offer a unique potential for various biomedical applications, but prior to commercial usage a standardized characterization of their structural and magnetic properties is required. For a thorough characterization, the…

Mesoscale and Nanoscale Physics · Physics 2020-08-18 Mathias Bersweiler , Helena Gavilan Rubio , Dirk Honecker , Andreas Michels , Philipp Bender

As the quality of the available galaxy cluster data improves, the models fitted to these data might be expected to become increasingly complex. Here we present the Bayesian approach to the problem of cluster data modelling: starting from…

Astrophysics · Physics 2009-11-10 P. J. Marshall , M. P. Hobson , A. Slosar

Bayesian methods are actively used for parameter identification and uncertainty quantification when solving nonlinear inverse problems with random noise. However, there are only few theoretical results justifying the Bayesian approach.…

Statistics Theory · Mathematics 2020-02-04 Vladimir Spokoiny

We develop a Bayesian approach for selecting the model which is the most supported by the data within a class of marginal models for categorical variables formulated through equality and/or inequality constraints on generalised logits…

Statistics Theory · Mathematics 2012-02-21 Francesco Bartolucci , Luisa Scaccia , Alessio Farcomeni

Large-amplitude prominence oscillations offer diagnostic information relevant to understanding the magnetic and plasma structure of solar prominences. Accurate prominence seismology requires the use of reliable models. The so-called…

Solar and Stellar Astrophysics · Physics 2026-04-02 Iñigo Arregui

Proton imaging is a powerful tool for probing electromagnetic fields in a plasma, providing a path-integrated map of the field topology. However, in cases where the field structure is highly inhomogeneous, inferring spatial properties of…

Plasma Physics · Physics 2019-10-10 Joseph Levesque , Carolyn Kuranz , Timothy Handy , Mario Manuel , Frederico Fiuza

We aim to characterise the surface magnetic fields of a sample of 8 T Tauri stars from high-resolution near-IR spectroscopy. Some stars in our sample are known to be magnetic from previous spectroscopic or spectropolarimetric studies. Our…

Solar and Stellar Astrophysics · Physics 2019-10-02 Alexis Lavail , Oleg Kochukhov , Gaitee Hussain

We present results of synthetic spectro-polarimetric diagnostics of radiative MHD simulations of solar surface convection with magnetic fields. Stokes profiles of Zeeman-sensitive lines of neutral iron in the visible and infrared spectral…

Astrophysics · Physics 2009-11-13 S. Shelyag , M. Schuessler , S. K. Solanki , A. Voegler

Variable selection for a multiple regression model (Noisy Linear Perceptron) is studied with a mean field approximation. In our Bayesian framework, variable selection is formulated as estimation of discrete parameters that indicate a subset…

Disordered Systems and Neural Networks · Physics 2007-05-23 Yukito Iba

This work presents a joint and self-consistent Bayesian treatment of various foreground and target contaminations when inferring cosmological power-spectra and three dimensional density fields from galaxy redshift surveys. This is achieved…

Cosmology and Nongalactic Astrophysics · Physics 2017-10-11 Jens Jasche , Guilhem Lavaux