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Radio and X-ray observations of galaxy clusters probe a direct link between cluster mergers and giant radio halos (RH), suggesting that these sources can be used as probes of the cluster merging rate with cosmic time. In this paper we carry…

Cosmology and Nongalactic Astrophysics · Physics 2016-09-28 R. Cassano , G. Brunetti , C. Giocoli , S. Ettori

A fraction of galaxy clusters host diffuse radio sources called radio halos, radio relics and mini-halos. We present the sample and first results from the Extended GMRT Radio Halo Survey (EGRHS)- an extension of the GMRT Radio Halo Survey…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-16 R. Kale , T. Venturi , S. Giacintucci , D. Dallacasa , R. Cassano , G. Brunetti , G. Macario , R. Athreya

Giant radio halos (RH) are Mpc-scale synchrotron sources detected in a significant fraction of massive and merging galaxy clusters.Their statistical properties can be used to discriminate among various models for their origin. Theoretical…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-11 R. Cassano , G. Brunetti , Ray P. Norris , H. J. A. Roettgering , M. Johnston-Hollitt , M. Trasatti

Giant radio halos are mega-parsec scale synchrotron sources detected in a fraction of massive and merging galaxy clusters. Radio halos provide one of the most important pieces of evidence for non-thermal components in large scale structure.…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-14 R. Cassano , G. Brunetti , H. J. A. Rottgering , M. Bruggen

We calculate the probability to form giant radio halos (~ 1 Mpc size) as a function of the mass of the host clusters by using a Statistical Magneto-Turbulent Model (Cassano & Brunetti, these proceedings). We show that the expectations of…

Astrophysics · Physics 2015-06-24 Rossella Cassano , Gianfranco Brunetti , Giancarlo Setti

We present the first high resolution MHD simulation of cosmic-ray electron reacceleration by turbulence in cluster mergers. We use an idealised model for cluster mergers, combined with a numerical model for the injection, cooling and…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-12 Julius Donnert , Klaus Dolag , Gianfranco Brunetti , Rossella Cassano

Giant Radio Halos (RH) are diffuse, Mpc-sized, synchrotron radio sources observed in a fraction of merging galaxy clusters. The current scenario for the origin of RHs assumes that turbulence generated during cluster mergers re-accelerates…

There are several possibilities to constrain the value of the magnetic field in the ICM, the most direct ones being the combination of inverse Compton and synchrotron observations, and the Faraday rotation measures. Here we discuss on the…

Astrophysics · Physics 2009-11-11 R. Cassano , G. Brunetti , G. Setti

A giant radio halo (RH) is a diffuse synchrotron emission observed on the scale of megaparsecs (Mpc), typically found in the central region of merging galaxy clusters. Its large size and steep spectrum suggest that it originates from the…

High Energy Astrophysical Phenomena · Physics 2024-11-20 Kosuke Nishiwaki , Katsuaki Asano

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…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-30 R. Cassano , G. Brunetti , T. Venturi

The underlying physics of giant radio halos and mini halos in galaxy clusters is still an open question, which becomes more pressing with the growing number of detections. In this paper, we explore the possibility that radio-emitting…

Cosmology and Nongalactic Astrophysics · Physics 2013-11-22 Fabio Zandanel , Christoph Pfrommer , Francisco Prada

The underlying physics of giant and mini radio halos in galaxy clusters is still an open question. We find that mini halos (such as in Perseus and Ophiuchus) can be explained by radio-emitting electrons that are generated in hadronic cosmic…

Cosmology and Nongalactic Astrophysics · Physics 2015-12-10 Fabio Zandanel , Christoph Pfrommer , Francisco Prada

Radio halos are synchrotron diffuse sources at the centre of a fraction of galaxy clusters. The study of large samples of clusters with adequate radio and X-ray data is necessary to investigate the origin of radio halos and their connection…

Cosmology and Nongalactic Astrophysics · Physics 2021-03-10 V. Cuciti , R. Cassano , G. Brunetti , D. Dallacasa , R. J. van Weeren , S. Giacintucci , A. Bonafede , F. de Gasperin , S. Ettori , R. Kale , G. W. Pratt , T. Venturi

Some galaxy clusters show diffuse radio emission in the form of giant halos (GHs) on Mpc scales or minihalos (MHs) on smaller scales. Comparing VLA and XMM radial profiles of several such clusters, we find a universal linear correlation…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 Uri Keshet , Abraham Loeb

We present new, high frequency radio observations of the merging galaxy clusters PLCK G287.0+32.9, Abell 2744, and Bullet. These clusters are known to host $\sim$Mpc scale sources, known as radio halos, which are formed by the acceleration…

Cosmology and Nongalactic Astrophysics · Physics 2025-08-20 K. Rajpurohit , A. Botteon , E. O'Sullivan , W. Forman , M. Balboni , L. Bruno , R. J. van Weeren , M. Hoeft , G. Brunetti , C. Jones , A. S. Rajpurohit , S. P. Sikhosana

The intra-cluster medium contains cosmic rays and magnetic fields that are manifested through the large scale synchrotron sources, termed as radio halos, relics and mini-halos. The Extended Giant Metrewave Radio Telescope (GMRT) Radio Halo…

Cosmology and Nongalactic Astrophysics · Physics 2015-07-08 R. Kale , T. Venturi , S. Giacintucci , D. Dallacasa , R. Cassano , G. Brunetti , V. Cuciti , G. Macario , R. Athreya

Several arguments have been presented in the literature to support the connection between radio halos and cluster mergers. The spectral index distributions of the halos in A665 and A2163 provide a new strong confirmation of this connection,…

Astrophysics · Physics 2015-06-24 L. Feretti , G. Brunetti , G. Giovannini , N. Kassim , E. Orru' , G. Setti

Context. Radio halos are megaparsec-scale diffuse radio sources{ mostly} located at the centres of merging galaxy clusters. The common mechanism invoked to explain their origin is the re-acceleration of relativistic particles caused by…

Cosmology and Nongalactic Astrophysics · Physics 2021-10-27 G. Di Gennaro , R. J. van Weeren , R. Cassano , G. Brunetti , M. Brüggen , M. Hoeft , E. Osinga , A. Botteon , V. Cuciti , F. de Gasperin , H. J. A. Röttgering , C. Tasse

We track the histories of massive clusters of galaxies formed within a cosmological hydrodynamic simulation. Specifically, we track the time evolution of the energy in random bulk motions of the intracluster medium and X-ray measures of…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-30 Eric J. Hallman , Tesla E. Jeltema

The Intra-Cluster Medium is characterized by thermal emission, and by the presence of large scale magnetic fields. In some clusters of galaxies a diffuse non-thermal emission is also present, located at the cluster center and named radio…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-14 G. Giovannini , A. Bonafede , L. Feretti , F. Govoni , M. Murgia , F. Ferrari , G. Monti