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Todays Colloquium: Magnetic fields and radio emission in galaxy clusters

Submitter: Annalisa Bonafede
Description: A fraction of galaxy clusters hosts diffuse radio emissions coming directly from the intra-cluster medium and not from the individual cluster radio-galaxies. These radio sources are known as radio haloes and radio relics, depending on their observational properties. The origin of such radio emission is still unknown, although in recent years much work has been done to understand the properties of the emitting particles and of the intra-cluster magnetic field.

I will present new radio observations of distant and massive galaxy clusters, discussing the properties of the newly discovered haloes and relics. By combining GMRT, EVLA and WSRT observations, the spectral indices and the polarization properties of these sources can be studied, and the origin of the emitting particles can be constrained. By comparing these new observations with high-resolution cosmological simulations we find that relics and haloes can be reproduced by converting a small fraction of the energy dissipated at the shock and from the turbulent energy.

Finally, I will discuss different methods to estimate the magnetic fields in radio haloes and relics, and I will present new observations and tecniques for the case of the Coma radio relic.

The figure shows the different components of the cluster MACSJ1752.0+4440 emission in the Xray (red), radio (blue) and optical (green).

Copyright: Annalisa Bonafede
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