Issue |
A&A
Volume 434, Number 1, April IV 2005
|
|
---|---|---|
Page(s) | 67 - 76 | |
Section | Cosmology (including clusters of galaxies) | |
DOI | https://doi.org/10.1051/0004-6361:20041839 | |
Published online | 01 April 2005 |
A Bayesian view on Faraday rotation maps – Seeing the magnetic power spectra in galaxy clusters
Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, Postfach 1317, 85741 Garching, Germany
Received:
12
August
2004
Accepted:
16
December
2004
We present a Bayesian maximum likelihood analysis of Faraday rotation
measure (RM) maps of extended radio sources to determine magnetic
field power spectra in clusters of galaxies. Using this approach, it is
possible to determine the uncertainties in the measurements. We apply
this approach to the RM map of Hydra A and derive the power spectrum
of the cluster magnetic field. For Hydra A, we measure a spectral index
of over at least one order of magnitude implying Kolmogorov type
turbulence. We find a dominant scale ~3 kpc on which the magnetic
power is concentrated, since the magnetic autocorrelation length is
kpc. Furthermore, we investigate the influences
of the assumption about the sampling volume (described by a window
function) on the magnetic power spectrum. The central magnetic field
strength was determined to be ~
G for the most
likely geometries.
Key words: magnetic fields / radiation mechanism: non-thermal / galaxies: active / interplanetary medium / galaxies: cluster: general / radio continuum: general
© ESO, 2005
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