The connection between radio halos and cluster mergers and the statistical properties of the radio halo population

Abstract

We discuss the statistical properties of the radio halo population in galaxy clusters. Radio bi-modality is observed in galaxy clusters: a fraction of clusters host giant radio halos while the majority of clusters do not show evidence of diffuse cluster-scale radio emission. The radio bi-modality has a correspondence in terms of dynamical state of the hosting clusters showing that merging clusters host radio halos and follow the well known radio--X-ray correlation, while more relaxed clusters do not host radio halos and populate a region well separated from that correlation. These evidences can be understood in the framework of a scenario where merger-driven turbulence re-accelerate the radio emitting electrons. We discuss the main statistical expectations of this scenario underlining the important role of upcoming LOFAR surveys to test present models.

11 pages, 2 figures, Invited talk at the conference "Diffuse Relativistic Plasmas", Bangalore, 1-4 March 2011; accepted for publication in the Journal of Astrophysics and Astronomy

References in corpus (15)

• Observations of extended radio emission in clusters
• On the connection between giant radio halos and cluster mergers
• The impact of mergers on relaxed X-ray clusters - I. Dynamical evolution and emergent transient structures
• A low-frequency radio halo associated with a cluster of galaxies
• Searching for Cool Core Clusters at High redshift
• GMRT Radio Halo Survey in galaxy clusters at z = 0.2 -- 0.4. II.The eBCS clusters and analysis of the complete sample
• GMRT Radio Halo Survey in galaxy clusters at z = 0.2 -- 0.4 I.The REFLEX sub--sample
• Statistics of Giant Radio Halos from Electron Reacceleration Models
• Cosmic ray transport in galaxy clusters: implications for radio halos, gamma-ray signatures, and cool core heating
• Diffuse Radio Emission in/around the Coma Cluster: Beyond Simple Accretion
• GeV Gamma-ray Flux Upper Limits from Clusters of Galaxies
• Cosmic rays and Radio Halos in galaxy clusters : new constraints from radio observations
• Rotation Measures of Radio Sources in Hot Galaxy Clusters
• Fractional polarization and magnetic fields in the ICM
• Revised statistics of radio halos and the re-acceleration model

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• Clusters of galaxies : observational properties of the diffuse radio emission
• The Radio Relics and Halo of El Gordo, a Massive $z=0.870$ Cluster Merger
• Cosmic Magnetism in Centimeter and Meter Wavelength Radio Astronomy
• A study of diffuse radio sources and X-ray emission in six massive clusters
• Low-frequency radio study of MACS clusters at 610 and 235 MHz using the GMRT
• Giant radio halos in galaxy clusters as probes of particle acceleration in turbulent regions