Estimation of Faraday Rotation Measures of the Near Galactic Sky Using a Nonstationary Gaussian Process Model

• Activity Number: 179
• Type: Contributed
• Date/Time: Monday, August 2, 2010 : 10:30 AM to 12:20 PM
• Sponsor: Section on Bayesian Statistical Science
• Author(s): Margaret Short*+ and Philipp P. Kronberg and Dave Higdon
• Companies: University of Alaska, Fairbanks and Los Alamos National Laboratory and Los Alamos National Laboratory
• Keywords: Faraday Rotation Measure ; nonstationary spatial process ; Bayesian model ; Markov chain Monte Carlo ; process convolution

Abstract

Our primary goal is to obtain a smoothed estimate of the magnetic field generated in and near to the Milky Way by using Faraday rotation measures (RMs). RMs provide an integrated measure of the effect of the magnetic field along the line of sight to extragalactic radio sources. The ability to estimate the magnetic field generated locally by our galaxy and its environs will help astronomers and astro-particle physicists distinguish local versus distant properties of the universe and compute magnetic deflections of the (mysterious) ultra high energy cosmic rays after they enter the Milky Way. We model these data using a Bayesian process convolution approach, fitted using MCMC. The model we present is an extension of an earlier model; it incorporates nonstationarity by allowing model parameters to vary with galactic latitude. We use a significantly enlarged and improved data set.