Observations of extended radio emission in clusters

C. Ferrari*, F. Govoni, S. Schindler, A. M. Bykov, Y. Rephaeli

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


We review observations of extended regions of radio emission in clusters; these include diffuse emission in 'relics', and the large central regions commonly referred to as 'halos'. The spectral observations, as well as Faraday rotation measurements of background and cluster radio sources, provide the main evidence for large-scale intracluster magnetic fields and significant densities of relativistic electrons. Implications from these observations on acceleration mechanisms of these electrons are reviewed, including turbulent and shock acceleration, and also the origin of some of the electrons in collisions of relativistic protons by ambient protons in the (thermal) gas. Improved knowledge of non-thermal phenomena in clusters requires more extensive and detailed radio measurements; we briefly review prospects for future observations.

Original languageEnglish
Pages (from-to)93-118
Number of pages26
JournalSpace Science Reviews
Issue number1-4
StatePublished - Feb 2008


  • Acceleration of particles
  • Galaxies: clusters: general
  • Galaxies: intergalactic medium
  • Magnetic fields
  • Radiation mechanisms: non-thermal
  • Radio continuum: general


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