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Non-thermal properties of galaxy clusters have been studied with detailed and deep radio images in comparison with X-ray data. While much progress has been made, most of the studied clusters are at a relatively low redshift (z < 0.3). We…

Cosmology and Nongalactic Astrophysics · Physics 2020-08-26 G. Giovannini , M. Cau , A. Bonafede , H. Ebeling , L. Feretti , M. Girardi , M. Gitti , F. Govoni , A. Ignesti , M. Murgia , G. B. Taylor , V. Vacca

Almost two decades of observations of radio emission in galaxy clusters have proven the existence of relativistic particles and magnetic fields that generate extended synchrotron emission in the form of radio halos. In the current scenario,…

Cosmology and Nongalactic Astrophysics · Physics 2017-08-28 G. Bernardi , T. Venturi , R. Cassano , G. Brunetti , D. Dallacasa , B. Fanaroff , B. Hugo , S. Makhatini , N. Oozeer , O. M. Smirnov , J. T. L. Zwart

{We simulate the evolution of relativistic electrons injected into the intracluster medium by five radio galaxies. We study the spatial transport and the emission properties of the injected radio plasma over a $\sim 5$ Gyr period, and the…

High Energy Astrophysical Phenomena · Physics 2023-03-10 F. Vazza , D. Wittor , M. Brueggen , G. Brunetti

We cross match the NVSS and FIRST surveys with three large photometric catalogues of luminous red galaxies (LRGs) to define radio-loud samples. These have median redshifts 0.35, 0.55 and 0.68 and, by matching rest-frame optical and radio…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-28 S. Fine , T. Shanks , N. Nikoloudakis , U. Sawangwit

Radio relics are diffuse radio sources observed in galaxy clusters, probably produced by shock acceleration during cluster-cluster mergers. Their large size, of the order of 1 Mpc, indicates that the emitting electrons need to be…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-18 A. Bonafede , H. T. Intema , M. Brüggen , M. Girardi , M. Nonino , N. Kantharia , R. J. van Weeren , H. J. A. Röttgering

Radio halos and relics are diffuse radio sources found in galaxy clusters showing significant substructure at X-ray wavelengths. These sources provide important information about non-thermal processes taking place in the ICM. Until now only…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-28 R. J. van Weeren , M. Bruggen , H. J. A. Rottgering , M. Hoeft , S. E. Nuza , H. T. Intema

Radio relics in galaxy clusters are associated with powerful shocks that (re)accelerate relativistic electrons. It is widely believed that the acceleration proceeds via diffusive shock acceleration. In the framework of thermal leakage, the…

High Energy Astrophysical Phenomena · Physics 2015-05-13 F. Vazza , D. Eckert , M. Brueggen , B. Huber

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

Aims. The statistical properties of radio halos can be used to discriminate among the possible models for their origin. Therefore an unbiased and exhaustive investigation in this direction is crucial. Methods. With this goal in mind in this…

Astrophysics · Physics 2009-11-13 R. Cassano , G. Brunetti , T. Venturi , G. Setti , D. Dallacasa , S. Giacintucci , S. Bardelli

Radio halos are elusive sources located at the center of merging galaxy clusters. To date, only about 40 radio halos are known, thus the discovery of new halos provide important insights on this class of sources. To improve the statistics…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-05 F. Govoni , C. Ferrari , L. Feretti , V. Vacca , M. Murgia , G. Giovannini , R. Perley , C. Benoist

We study the relation between radio halos, the energy input by supernovae in the disk and the galaxy mass. We find that both the energy input by supernovae as well as the galaxy mass are important parameters for understanding the formation…

Astrophysics · Physics 2015-06-24 Ute Lisenfeld , Michael Dahlem , Matthias Ehle

We review observations of extended regions of radio emission in clusters; these include diffuse emission in `relics', and the large central regions commonly referred to as `halos'. The spectral observations, as well as Faraday rotation…

Astrophysics · Physics 2009-11-13 C. Ferrari , F. Govoni , S. Schindler , A. M. Bykov , Y. Rephaeli

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

We performed GMRT low frequency observations of the radio halos, relics and new candidates belonging to the GMRT Radio Halo Cluster Sample first observed at 610 MHz. High sensitivity imaging was performed using the GMRT at 325 MHz and 240…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-11 Tiziana Venturi , Simona Giacintucci , Daniele Dallacasa , Rossella Cassano , Gianfranco Brunetti , Giulia Macario , Ramana Athreya

A very important aspect of the radio emission from galaxy clusters is represented by the diffuse radio sources associated with the intracluster medium: radio halos and relics. These radio sources indicate the existence of large scale…

Astrophysics · Physics 2007-05-23 Luigina Feretti

As energetic particles diffuse out of radio and star-forming galaxies (SFGs), their intracluster density builds up to a level that could account for a substantial part or all the emission from a radio halo. We calculate the particle…

High Energy Astrophysical Phenomena · Physics 2016-06-01 Yoel Rephaeli , Sharon Sadeh

About 1/3 of X-ray-luminous clusters show smooth, unpolarized radio emission on ~Mpc scales, known as giant radio halos. One promising model for radio halos is Fermi-II acceleration of seed relativistic electrons by turbulence of the…

High Energy Astrophysical Phenomena · Physics 2015-03-30 Anders Pinzke , S. Peng Oh , Christoph Pfrommer

Many bright radio relics in the outskirts of galaxy clusters have low inferred Mach numbers, defying expectations from shock acceleration theory and heliospheric observations that the injection efficiency of relativistic particles plummets…

Cosmology and Nongalactic Astrophysics · Physics 2013-09-03 Anders Pinzke , S. Peng Oh , Christoph Pfrommer

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

The frequently observed association between giant radio halos and merging galaxy clusters has driven present theoretical models of non-thermal emission from galaxy clusters, which are based on the idea that the energy dissipated during…

Cosmology and Nongalactic Astrophysics · Physics 2010-11-09 R. Cassano , S. Ettori , S. Giacintucci , G. Brunetti , M. Markevitch , T. Venturi , M. Gitti