Details

Autor(en) / Beteiligte

• Eckert, D.
• Gaspari, M.
• Vazza, F.
• Gastaldello, F.
• Tramacere, A.
• Zimmer, S.
• Ettori, S.
• Paltani, S.

Titel

On the Connection between Turbulent Motions and Particle Acceleration in Galaxy Clusters

Ist Teil von

• Astrophysical journal. Letters, 2017-07, Vol.843 (2), p.L29

Ort / Verlag

Austin: The American Astronomical Society

Erscheinungsjahr

2017

Link zum Volltext

Quelle

EZB-FREE-00999 freely available EZB journals

Beschreibungen/Notizen

• Giant radio halos are megaparsec-scale diffuse radio sources associated with the central regions of galaxy clusters. The most promising scenario to explain the origin of these sources is that of turbulent re-acceleration, in which MeV electrons injected throughout the formation history of galaxy clusters are accelerated to higher energies by turbulent motions mostly induced by cluster mergers. In this Letter, we use the amplitude of density fluctuations in the intracluster medium as a proxy for the turbulent velocity and apply this technique to a sample of 51 clusters with available radio data. Our results indicate a segregation in the turbulent velocity of radio halo and radio quiet clusters, with the turbulent velocity of the former being on average higher by about a factor of two. The velocity dispersion recovered with this technique correlates with the measured radio power through the relation , which implies that the radio power is nearly proportional to the turbulent energy rate. In case turbulence cascades without being dissipated down to the particle acceleration scales, our results provide an observational confirmation of a key prediction of the turbulent re-acceleration model and possibly shed light on the origin of radio halos.