MAGNETIC FIELDS IN CLUSTERS OF GALAXIES

By F. Govoni, L. Feretti. 2004

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The existence of magnetic fields associated with the intracluster medium in clusters of galaxies is now well established through different methods of analysis. Magnetic fields are investigated in the radio band from studies of the rotation measure of polarized radio galaxies and the synchrotron emission of cluster-wide diffuse sources. Other techniques include X-ray studies of the inverse Compton emission and of cold fronts and magneto hydrodynamic simulations. We review the main issues that have led to our knowledge on magnetic fields in clusters of galaxies. Observations show that cluster fields are at the μG level, with values up to tens of μG at the center of cooling core clusters. Estimates obtained from different observational approaches may differ by about an order of magnitude. However, the discrepancy may be alleviated by considering that the magnetic field is not constant throughout the cluster, and shows a complex structure. In particular, the magnetic field intensity declines with the cluster ...

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/d9abe648c7d658d1b142126fc1000514e8480cec

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Citations in the corpus

Cluster magnetic fields from galactic outflows (2008, background): “…observations, via the Faraday rotation signal of the magnetized cluster atmosphere towards polarized radio sources in or behind clusters (Carilli & Taylor 2002) and from diffuse synchrotron emission of the cluster atmosphere (see Govoni & Feretti 2004; Ferrari et al. 2008, for recent reviews).”
NuSTAR OBSERVATIONS OF THE BULLET CLUSTER: CONSTRAINTS ON INVERSE COMPTON EMISSION (2014, background): “A number of observations, mainly at radio frequencies, have established that relativistic particles and magnetic fields are part of the intracluster medium (ICM) of galaxy clusters (e.g., Govoni & Feretti 2004).”
Revised equipartition and minimum energy formula for magnetic field strength estimates from radio synchrotron observations (2005, methodology): “The ratio of radio to X-ray intensities can be used as a measure of field strength (Harris & Grindlay 1979; Govoni & Feretti 2004).”
Shock waves in Eulerian cosmological simulations: main properties and acceleration of cosmic rays (2008, background): “…and actually represent a challenge for simulations: in the case that the ICM is magnetized at ≈ μG level (consistent with rotation measures; e.g. Govoni & Feretti 2004) the energy of CR should be at ≤few per cent of the thermal energy (when the spectrum of CR is fixed at that expected from…”
An MHD gadget for cosmological simulations (2008, background): “…of the magnetized cluster atmosphere towards polarized radio sources in or behindclusters (see Carilli & Taylor 2002; Govoni & Feretti 2004,for recent reviews) and from diffuse synchrotron emission of the cluster a mosphere (see Govoni & Feretti 2004; Ferrari et al. 2008, for recent reviews).”
Diffuse Radio Emission from Galaxy Clusters (2019, methodology): “The most promising technique to derive a more detailed view of the magnetic fields in clusters is via the analysis of the Faraday rotation of radio galaxies located inside and behind the cluster (e.g., Clarke 2004; Govoni & Feretti 2004).”
GMRT radio halo survey in galaxy clusters at z = 0.2–0.4 - II. The eBCS clusters and analysis of the complete sample (2008, background): “Recent studies revealed that the magnetic fields in galaxy clusters are weak, with strength in the range ∼ 0.1− 1 µG (for recent reviews see Govoni & Feretti 2004 and Ferrari et al. 2008).”
Simulations of magnetic fields in isolated disc galaxies (2012, background): “They are observed on vastly different scales, from the interiors of stars to interstellar gas, from haloes of galaxies to galaxy clusters (see, e.g., Parker 1979; Beck et al. 1996; Kulsrud 1999; Carilli & Taylor 2002; Govoni & Feretti 2004).”
DIFFUSIVE SHOCK ACCELERATION SIMULATIONS OF RADIO RELICS (2012, background): “The presence of energetic nonthermal particles, especially electrons, in clusters of galax- ies has been inferred from observations of so-called “radio halos” and “radio relics” (see, e.g., Carilli & Taylor 2002; Govoni & Feretti 2004; Ferrari et al. 2008; Brüggen et al. 2011, for reviews).”
Radio signature of cosmological structure formation shocks (2006, background): “Unfortunately, the magnetic field distribution in clusters of galaxies and their surroundings is difficult to determine and still poorly constrained (for a review see Govoni & Feretti 2004).”
Evolving turbulence and magnetic fields in galaxy clusters (2005, background): “However, the fractional polarization observed from cluster radio haloes is less than 2–10 per cent at the wavelength λ = 21 cm (L. Feretti private communication; Govoni & Feretti 2004).”
Planck 2015 results: XIX. Constraints on primordial magnetic fields (2015, unknown): “Large-scale magnetic fields are also probed in galaxy clusters, both through the measurement of the Faraday rotation effect on the light of background galaxies and through radio emission from the halos and relics of the clusters (Govoni & Feretti 2004; Ferrari et al. 2008; Feretti et al. 2012).”