Gianfranco Brunetti

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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)
  • G Brunetti, S Giacintucci, +7 authors M Markevitch
  • 2008
Clusters of galaxies are the largest gravitationally bound objects in the Universe, containing about 10 15 solar masses of hot (10 8 K) gas, galaxies and dark matter in a typical volume of about 10Mpc 3. Magnetic fields and relativistic particles are mixed with the gas as revealed by giant radio haloes, which arise from diffuse, megaparsec-scale synchrotron(More)
We attempt to explain the non-thermal emission arising from galaxy clusters as a result of the re–acceleration of electrons by compressible turbulence induced by cluster mergers. On the basis of the available observational facts we put forward a simplified model of turbulence in clusters of galaxies focusing our attention on the compress-ible motions. In(More)
We have implemented an Adaptive Mesh Refinement criterion explicitly designed to increase spatial resolution around discontinuities in the velocity field in ENZO cosmological simulations. With this technique, shocks and turbulent eddies developed during the hierarchical assembly of galaxy clusters are followed with unprecedented spatial resolution, even at(More)
We use the results from a constrained, cosmological MHD simulation of the Local Universe to predict the radio halo and the gamma-ray flux from the Coma cluster and compare it to current observations. The simulated magnetic field within the Coma cluster is the result of turbulent amplification of the magnetic field during build-up of the cluster. The(More)
1. ABSTRACT 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(More)
In the next years the FERMI gamma ray telescope and the Cherenkov telescopes will put very stringent constraints to models of gamma ray emission from galaxy clusters providing crucial information on relativistic particles in the inter-galactic-medium. We derive the broad band non-thermal spectrum of galaxy clusters in the context of general calculations in(More)
1 RESUMEN ABSTRACT 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(More)
Received Day Month Year Revised Day Month Year Clusters of galaxies and the large scale filaments that connect neighboring clusters are expected to be sites of acceleration of charged particles and sources of non-thermal radiation from radio frequencies to gamma rays. Gamma rays are particularly interesting targets of investigation, since they may provide(More)
Hot spots (HSs) are regions of enhanced radio emission produced by supersonic jets at the tip of the radio lobes of powerful radio sources. Obtained with the Very Large Telescope (VLT), images of the HSs in the radio galaxy 3C 445 show bright knots embedded in diffuse optical emission distributed along the post-shock region created by the impact of the jet(More)