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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

we present new VLA observations at 1.4 GHz confirming the presence of a radio halo at the centre of the cluster A3562, in the core of the Shapley Concentration. We also report a detailed multifrequency radio study of the head tail galaxy…

We present new Chandra X-ray and Giant Meterwave Radio Telescope (GMRT) radio observations of the nearby merging galaxy cluster Abell 754. Our X-ray data confirm the presence of a shock front by obtaining the first direct measurement of a…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-20 Giulia Macario , Maxim Markevitch , Simona Giacintucci , Gianfranco Brunetti , Tiziana Venturi , Stephen S. Murray

Some merging galaxy clusters host diffuse elongated radio sources, also called radio relics. It is proposed that these radio relics trace shock waves in the intracluster medium created during a cluster merger event. Within the shock waves…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-27 R. J. van Weeren , M. Hoeft , H. J. A. Rottgering , M. Bruggen , H. T. Intema , S. van Velzen

We seek to explore the internal dynamics of the cluster Abell 1758N, which has been shown to host a radio halo and two relics, and is known to be a merging bimodal cluster. Our analysis is mainly based on new redshift data for 137 galaxies…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-04 W. Boschin , M. Girardi , R. Barrena , M. Nonino

We present a multi-wavelength analysis of the merging rich cluster of galaxies Abell 2256. We have observed A2256 at 150 MHz using the Giant Metrewave Radio Telescope and successfully detected the diffuse radio halo and the relic emission…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-19 Kale Ruta , K. S. Dwarakanath

Deep (103 ks) \chandra\ observations of Abell 665 have revealed rich structures in this merging galaxy cluster, including a strong shock and two cold fronts. The newly discovered shock has a Mach number of $M$ = 3.0 $\pm$ 0.6, propagating…

We aim to obtain new insights into the internal dynamics of the cluster Abell 2345. This cluster exhibits two non-symmetric radio relics well studied through recent, deep radio data. Our analysis is based on redshift data for 125 galaxies…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-19 Walter Boschin , Rafael Barrena , Marisa Girardi

We report on the detection of a giant radio halo in the cluster Abell 3404 as well as confirmation of the radio halo observed in Abell 141 (with linear extents $\sim 770$ kpc and $\sim 850$ kpc, respectively). We use the Murchison Widefield…

Cosmology and Nongalactic Astrophysics · Physics 2021-07-14 S. W. Duchesne , M. Johnston-Hollitt , A. G. Wilber

Massive structures like cluster of galaxies, embedded in cosmic filaments, release enormous amount of energy through their interactions. These events are associated with production of Mpc-scale shocks and injection of considerable amount of…

Cosmology and Nongalactic Astrophysics · Physics 2011-04-27 S. Paul , L. Iapichino , F. Miniati , J. Bagchi , K. Mannheim

We explore the internal dynamics of Abell 2254, which has been shown to host a very clumpy and irregular radio halo. Our analysis is mainly based on redshift data for 128 galaxies acquired at the TNG. We also use new g',r',i' photometric…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-30 M. Girardi , S. Bardelli , R. Barrena , W. Boschin , F. Gastaldello , M. Nonino

We present the first band-2 (120--250\,MHz) uGMRT (upgraded Giant Metrewave Radio Telescope) observations of the bimodal galaxy cluster Abell\,1644 (\(z = 0.0471\)), complemented by Chandra X-ray data. While weak lensing measurements reveal…

Astrophysics of Galaxies · Physics 2025-12-24 Humaira Bashir , R. Kale , Asif Iqbal , Manzoor A. Malik

The connection of cluster mergers with the presence of extended, diffuse radio sources in galaxy clusters is still debated. An interesting case is the rich, merging cluster Abell 520, containing a radio halo. A recent gravitational analysis…

Astrophysics · Physics 2009-11-13 M. Girardi , R. Barrena , W. Boschin , E. Ellingson

We have performed 323 MHz observations with the Giant Metrewave Radio Telescope of the most promising candidates selected from the MACS catalog. The aim of the work is to extend our knowledge of the radio halo and relic populations to…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-05 A. Bonafede , M Brueggen , R. van Weeren , F. Vazza , G. Giovannini , H. Ebeling , A. C. Edge , M. Hoeft , U. Klein

Abell 3266 is a massive and complex merging galaxy cluster that exhibits significant substructure. We present new, highly sensitive radio continuum observations of Abell 3266 performed with the Australian Square Kilometre Array Pathfinder…

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

Extended, steep-spectrum radio synchrotron sources are pre-dominantly found in massive galaxy clusters as opposed to groups. LOFAR Two-Metre Sky Survey images have revealed a diffuse, ultra-steep spectrum radio source in the low-mass…

Galaxy-cluster merger shocks efficiently accelerate the ambient electrons through diffusive shock acceleration and amplify magnetic field by compressing the Inter Cluster Medium. As a result, such objects produce a significant amount of…

Cosmology and Nongalactic Astrophysics · Physics 2017-06-29 S. Paul , A. Datta , H. T. Intema

New adaptive mesh refinement N-body + hydrodynamics numerical simulations are used to illustrate the complex and changing cluster environments in which many radio galaxies live and evolve. Groups and clusters of galaxies form at the…

Astrophysics · Physics 2009-10-31 J. O. Burns , C. Loken , K. Roettiger , E. Rizza , G. Bryan , M. L. Norman , P. Gomez , F. N. Owen

Previously it has been recognized that radio halos in galaxy clusters are preferentially associated with merging systems as indicated by substructure in the X-ray images and temperature maps. Since, however, many clusters without radio…

Astrophysics · Physics 2009-11-06 David A. Buote