Gianfranco Brunetti

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X iv :0 81 0. 42 88 v1 [ as tr oph ] 2 3 O ct 2 00 8 A low-frequency radio halo associated with a cluster of galaxies G. Brunetti1,S. Giacintucci1,2, R. Cassano1,W. Lane3, D. Dallacasa4,T. Venturi1, N. Kassim3, G. Setti1,4, W. D. Cotton5, & M. Markevitch2 1INAF Istituto di Radioastronomia, Via P. Gobetti 101, I-40129 Bologna, Italy 2Harvard-Smithsonian(More)
Smoothed particle hydrodynamics (SPH) employs an artificial viscosity to properly capture hydrodynamical shock waves. In its original formulation, the resulting numerical viscosity is large enough to suppress structure in the velocity field on scales well above the nominal resolution limit, and to damp the generation of turbulence by fluid instabilities.(More)
The most important evidence of non–thermal phenomena in galaxy clusters comes from Giant Radio Halos (GRHs), spectacular synchrotron radio sources extended over >Mpc scales, detected in the central regions of a growing number of massive galaxy clusters. A promising possibility to explain these sources is given by in situ stochastic reacceleration of(More)
In the framework of the study of extragalactic radio sources, we will focus on the importance of the spatial resolution at different wavelengths, and of the combination of observations at different frequency bands. In particular, a substantial step forward in this field is now provided by the new generation X-ray telescopes which are able to image radio(More)
Aims. We present the first results of an ongoing project devoted to the search of giant radio halos in galaxy clusters located in the redshift range z=0.2–0.4. One of the main goals of our study is to measure the fraction of massive galaxy clusters in this redshift interval hosting a radio halo, and to constrain the expectations of the particle(More)
We present a new detailed multiband study of the merging cluster A3562, in the core of the Shapley Concentration Supercluster. We analyzed new, low frequency radio data performed at 240 MHz, 332 MHz and 610 MHz with the Giant Metrewave Radio Telescope (GMRT). The new GMRT data allowed us to carry out a detailed study of the radio halo at the centre of(More)
Aims. We present new high sensitivity observations of the radio relic in A 521 carried out with the Giant Metrewave Radio Telescope at 327 MHz and with the Very Large Array at 4.9 and 8.5 GHz. Methods. We imaged the relic at these frequencies and carried out a detailed spectral analysis, based on the integrated radio spectrum between 235 MHz and 4.9 GHz,(More)
Many galaxy clusters host Megaparsec-scale radio halos, generated by ultrarelativistic electrons in the magnetized intracluster medium. Correlations between the synchrotron power of radio halos and the thermal properties of the hosting clusters were established in the last decade, including the connection between the presence of a halo and cluster mergers.(More)
In a previous paper (Brunetti et al. 2004) we presented the first self-consistent calculations of the time-dependent coupled equations for the electrons, hadrons and Alfvén waves in the intracluster medium, which describe the stochastic acceleration of the charged particles and the corresponding spectral modification of the waves. Under viable assumptions,(More)
FERMI (formely GLAST) and LOFAR will shortly provide crucial information on the non-thermal components (relativistic particles and magnetic field) in galaxy clusters. After discussing observational facts that already put constraints on the properties and origin of non-thermal components, I will report on the emission spectrum from galaxy clusters as(More)