The Coma cluster magnetic field from Faraday rotation measures

By A. Bonafede, L. Feretti, M. Murgia, F. Govoni, G. Giovannini, D. Dallacasa, Klaus Dolag, G. B. Taylor. 2009

371 citations recorded by the source corpus.

Aims. The aim of the present work is to constrain the Coma cluster magnetic field strength, its radial profile and power spectrum by comparing Faraday rotation measure (RM) images with numerical simulations of the magnetic field. Methods. We have analyzed polarization data for seven radio sources in the Coma cluster field observed with the Very Large Array at 3.6, 6 and 20 cm, and derived Faraday rotation measures with kiloparsec scale resolution. Random three dimensional magnetic field models have been simulated for various values of the central intensity B0 and radial power-law slope η ,w hereη indicates how the field scales with respect to the gas density profile. Results. We derive the central magnetic field strength, and radial profile values that best reproduce the RM observations. We find that the magnetic field power spectrum is well represented by a Kolmogorov power spectrum with minimum scale ∼2 kpc and maximum scale ∼34 kpc. The central magnetic field strength and radial slope are constrained to be in the range (B0 = 3.9 μG; η = 0.4) and (B0 = 5.4 μG; η = 0.7) within 1σ. The best agreement between observations and simulations is achieved for B0 = 4.7 μG; η = 0.5. Values of B0 > 7 μ Ga nd 1.0 are incompatible with RM data at 99% confidence level.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/6d13f0c9920893184f8a4c84ccd5d677adeddfd4

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Citations in the corpus

An improved map of the Galactic Faraday sky (2011, background): “(12) To estimate the cluster contribution σ(cluster), Bonafede et al. (2010) studied resolved background sources for which several independent RM measurements are possible. σ(cluster) was then identified with the empirical value of the standard deviation of these measurements.”
Massive and refined - II. The statistical properties of turbulent motions in massive galaxy clusters with high spatial resolution (2010, background): “These studies show that the magnetic ﬁeld in the ICM is tan-gled on a broad range of spatial scales (e.g. Murgia et al. 2004; Vogt & Ensslin 2005; Bonafede et al. 2010; Govoni et al. 2010; Vacca et al. 2010) suggesting the presence of super–Alfv´enic motions in the medium.”
NuSTAR OBSERVATIONS OF THE BULLET CLUSTER: CONSTRAINTS ON INVERSE COMPTON EMISSION (2014, background): “…such lower limits are more consistent with equipartition estimates (∼ 1 µG for the Bullet cluster, Petrosian et al. 2006) and Faraday rotation measure estimates in other clusters, which typically place the field strength at a few µG (e.g., Kim et al. 1990; Clarke et al. 2001; Bonafede et al. 2010).”
Magnetic Fields in the Large-Scale Structure of the Universe (2011, methodology): “Turbulence in the ICM was also studied in RM maps of a few clusters (Vogt and Enßlin 2005, Guidetti et al. 2008, Bonafede et al. 2010).”
Cosmological Magnetic Fields: Their Generation, Evolution and Observation (2013, background): “…Versoix,Switzerland Fletcher 2011; Beck 2012) and high redshift (Kronberg et al 1992; Bernet et al 2008) galaxies, in galaxy clusters (Clarke et al 2001; Bonafede et al 2010; Feretti et al 2012), in superclusters (Xu et al 2006) and even in voids of the Large Scale Structure (LSS) (Neronov and…”
Diffuse Radio Emission from Galaxy Clusters (2019, background): “The best studied cluster is Coma, whose magnetic field has been obtained with RM information on 7 radio galaxies in the cluster central region (Bonafede et al. 2010), and 7 additional radio galaxies in the peripheral Coma southwest region, where the NGC 4839 infalling group and the cluster radio…”
Complex Faraday depth structure of active galactic nuclei as revealed by broad‐band radio polarimetry (2012, background): “…Brown et al. 2007; Taylor, Stil & Sunstrum 2009; Mao et al. 2010; Harvey-Smith, Madsen & Gaensler 2011; Van Eck et al. 2011), other galaxies (e.g. Gaensler et al. 2005; Mao et al. 2008; Feain et al. 2009) and in galaxy clusters (e.g. Laing et al. 2008; Bonafede et al. 2010; Pizzo et al. 2011).”
Acceleration of primary and secondary particles in galaxy clusters by compressible MHD turbulence: from radio haloes to gamma-rays (2010, methodology): “…in the Alfvenic case (Brunetti & Blasi 2005) c© 0000 RAS, MNRAS 000, 000–000 For seek of completeness, in Figure 5 (lower panels) we show the expected SED of the Coma cluster by assuming a magnetic field in the cluster 2.5 times smaller than that inferred from Bonafede et al.(2010) (see caption).”