A Bayesian view on Faraday rotation maps - Seeing the magnetic power spectra in galaxy clusters

By C. Vogt, Torsten A. Ensslin. 2005

193 citations recorded by the source corpus.

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 −5/3 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 λB = 3 ± 0.5 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 ∼7 ± 2 µG for the most likely geometries.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/d0890391a8fd15a6aa5fcbd4d0ccd1c92d3dae76

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

Citations in the corpus

The Interplay of Magnetically Dominated Turbulence and Magnetic Reconnection in Producing Nonthermal Particles (2019, background): “…& Hawley 1998; Brandenburg & Subramanian 2005), jets from active galactic nuclei (Marscher et al. 2008; MacDonald & Marscher 2018), radio lobes (Vogt & Enßlin 2005; O’Sullivan et al. 2009), gamma-ray bursts (Piran 2004; Kumar & Narayan 2009), and galaxy clusters (Zweibel & Heiles 1997;…”
The intracluster magnetic field power spectrum in Abell 665 (2007, background): “Recent results show that the magnetic field power spectrum can be estimated if very detailed rotation-measure images of cluster radio galaxies are available (Enßlin & Vogt 2003; Murgia et al. 2004; Vogt & Enßlin 2005; Govoni et al. 2006; Guidetti et al. 2008; Laing et al. 2008).”
ASTROPHYSICAL GYROKINETICS: KINETIC AND FLUID TURBULENT CASCADES IN MAGNETIZED WEAKLY COLLISIONAL PLASMAS (2007, background): “Fluctuations of electron density, temperature and of magnetic fields are measured in clusters by X-ray and radio observatories, but the resolution is only just enough to claim that a fairly broad scale range of fluctuations exists (Schuecker et al. 2004; Vogt & Enßlin 2005).”
Evolving turbulence and magnetic fields in galaxy clusters (2005, methodology): “Vogt & Enßlin (2003, 2005), using a novel technique (Enßlin & Vogt 2003), estimate magnetic field strength to be 3 μG in A2634, 6 μG in A400 and 7 μG in Hydra A.”
Compressible turbulence in galaxy clusters: physics and stochastic particle re-acceleration (2007, background): “We note that indeed recent Bayesian analysis of RM show that magnetic fields in galaxy clusters could be tangled at least on scales ≈ kpc (Vogt & Ensslin 2005), smaller scales being inaccessible to observations, thus suggesting that the bending of the field lines happens on scales lmfp.”
Cluster magnetic fields from galactic outflows (2008, background): “From such observations, once can constrain the power-law spectral index (Murgia et al. 2004; Govoni et al. 2006) or directly reconstruct the power spectrum of the magnetic field (Vogt & Enßlin 2003, 2005).”
Astrophysical magnetic fields and nonlinear dynamo theory (2004, methodology): “(For Hydra A, a recent re-analysis of the data using an improved RM map and revised cluster parameters, has led to revised values of the central field of the cluster of 7 G and 27 correlation length of 3 kpc, as well as a tentative determination of a Kolmogorov type magnetic power spectrum [137].”