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measuring magnetic power spectra of Hydra A Petr Kuchar, Torsten Ensslin
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Hydra A opticalx-ray NASA/CXC/SAO La Palma/B. McNamara
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Hydra A radio RM map Greg Taylor, NRAO pacerman algorithm Dolag & Vogt & Ensslin
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we measure this rotation measure we want that
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previous works Laing 2008 compare observed and computed structure function Vogt & Ensslin 2005 Bayesian
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Bayesian approach given RM data d wanted power spectrum p P(p|d)~P(d|p)P(p) Likelihood Jeffrey's Prior
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correlation matrix C electron density magnetic density cavity geometry projection angle of jet powerspectrum
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maximize the posterior P(p|d) analytical expressions for gradient and hessian
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power spectrum
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spectral index
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projection angle
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characteristics of magnetic field magnetic density: autocorrelation lengths spectral index
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conclusion maximum a posteriori method to retrieve magnetic power spectra re-analysis of Hydra A data (as Vogt & Ensslin) now including cavities, noise, Galactic foreground, beam discussion, increased internal accuracy robust results: peaked spectrum with 3 kpc correlation length, indication of power-law inertia range on smaller scales required: better understanding of RM noise & beam effects, window effects on large scales
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