Magnetic fields in the 3C 129 cluster

Abstract

We present multifrequency VLA observations of the two radio galaxies 3C 129 and 3C 129.1 embedded in a luminous X‐ray cluster. These radio observations reveal a substantial difference in the Faraday Rotation Measures (RMs) toward 3C 129.1 at the cluster centre and 3C 129 at the cluster periphery. After deriving the density profile from available X‐ray data, we find that the RM structure of both radio galaxies can be fitted by a tangled cluster magnetic field with strength 6 μG extending at least 3 core radii (450 kpc) from the cluster centre. The magnetic field makes up a small contribution to the total pressure (5 per cent) in the central regions of the cluster. The radio morphology of 3C 129.1 appears disturbed on the southern side, perhaps by the higher pressure environment. In contrast with earlier claims for the presence of a moderately strong cooling flow in the 3C 129 cluster, our analysis of the X‐ray data places a limit on the mass deposition rate from any such flow of < 1.2 M⊙ yr−1.

Rotation measures of radio sources in hot galaxy clusters

“…Lawler & Dennison 1982; Appendix is only available in electronic form at http://www.aanda.org Vallée et al 1986;Kim et al 1990Kim et al , 1991Clarke et al 2001) and individual galaxy clusters and galaxy groups by analyzing detailed high resolution RM images (e.g. Perley & Taylor 1991;Taylor & Perley 1993;Feretti et al 1995Feretti et al , 1999aGovoni et al 2001;Taylor et al 2001;Eilek & Owen 2002;Govoni et al 2006;Taylor et al 2007;Guidetti et al 2008;Laing et al 2008;Guidetti et al 2010;Bonafede et al 2010). These data are usually consistent with central magnetic field strengths of a few μG, but stronger fields, with values exceeding 10 μG, are derived in the inner regions of relaxed cooling core clusters.…”

Observations of magnetic fields in regular and irregular clusters

“…Another beautiful example is 3C75 at the center of the irregular cluster A400 (Eilek & Owen 2002) where the RM values are high (hundreds rad/m 2 ) but not so high as at the center of cooling cores clusters. The ideal case to study the cluster magnetic field is to sample the RM in a number as large as possible of extended radio galaxies located in the same cluster of galaxies Govoni et al 2001b;Taylor et al 2001). Figure 2 shows RM images obtained for four radio galaxies in the irregular cluster A2255 (Govoni et al in preparation).…”

Sardinia Radio Telescope observations of Abell 194

“…Clarke et al 2001, Johnston-Hollitt & Ekers 2004) as well as individual clusters (e.g. Perley & Taylor 1991, Taylor & Perley 1993, Feretti et al 1995, Taylor et al 2001, Eilek & Owen 2002, Pratley et al 2013). These studies reveal that magnetic fields are widespread in the intracluster medium, regardless of the presence of a diffuse radio halo emission.…”