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Accretion of gas onto already virialized structures like galaxy clusters should give rise to accretion shocks which can potentially accelerate cosmic rays. Here, we use the radio emission detected from Coma cluster and models of evolution…

High Energy Astrophysical Phenomena · Physics 2018-02-27 A. Ćiprijanović , T. Prodanović , M. Z. Pavlović

Inhomogeneities can influence the polarisation emerging from a synchrotron source. However, it is shown that the frequency distribution of circular polarisation is only marginally affected, although its magnitude may change substantially.…

High Energy Astrophysical Phenomena · Physics 2020-05-13 C. -I. Bjornsson

Some galaxy clusters show diffuse radio emission in the form of peripheral relics (so far attributed to primary, shock-(re)accelerated electrons) or central halos. Analysing radio and X-ray data from the literature, we find new connections…

High Energy Astrophysical Phenomena · Physics 2010-11-04 Uri Keshet

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

Recently Vernstrom et al. (2021) claimed the first definitive detection of the synchrotron cosmic web, obtained by `stacking' hundreds of thousands of pairs of close-proximity clusters in low-frequency radio observations and looking for a…

Cosmology and Nongalactic Astrophysics · Physics 2022-08-08 Torrance Hodgson , Franco Vazza , Melanie Johnston-Hollitt , Benjamin McKinley

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 Relics are typically found to be arc-like regions of synchrotron emission in the outskirts of merging galaxy clusters, bowing out from the cluster center. In most cases they show synchrotron spectra that steepen towards the cluster…

High Energy Astrophysical Phenomena · Physics 2023-11-07 Ludwig M. Böss , Ulrich P. Steinwandel , Klaus Dolag

It has been proposed that the cool cores of galaxy clusters are stably heated by cosmic rays (CRs). If this is the case, radio mini-halos, which are often found in the central regions of cool core clusters, may be attributed to the…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-11 Yutaka Fujita , Yutaka Ohira

As is known, resonant scattering can distort the surface-brightness profiles of clusters of galaxies in X-ray lines. We demonstrate that the scattered line emission should be polarized and possibly detectable with near-future X-ray…

Astrophysics · Physics 2009-11-07 S. Sazonov , E. Churazov , R. Sunyaev

We report the discovery of a unique radio galaxy at z=0.137, which could possibly be the second spiral-host large radio galaxy and also the second triple-double episodic radio galaxy. The host galaxy shows signs of recent star formation in…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-28 Ananda Hota , S. K. Sirothia , Youichi Ohyama , C. Konar , Suk Kim , Soo-Chang Rey , D. J. Saikia , J. H. Croston , Satoki Matsushita

Cosmological shocks are a critical part of large-scale structure formation, and are responsible for heating the intracluster medium in galaxy clusters. In addition, they are also capable of accelerating non-thermal electrons and protons. In…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-19 Samuel W. Skillman , Eric J. Hallman , Brian W. O'Shea , Jack O. Burns , Britton D. Smith , Matthew J. Turk

Radio observations over the last two decades have provided evidence that diffuse synchrotron emission in the form of megaparsec-scale radio halos in galaxy clusters is likely tracing regions of the intracluster medium where relativistic…

Cosmology and Nongalactic Astrophysics · Physics 2016-03-25 G. Bernardi , T. Venturi , R. Cassano , D. Dallacasa , G. Brunetti , V. Cuciti , M. Johnston-Hollitt , N. Oozeer , O. M. Smirnov

Observations of diffuse radio emission in galaxy clusters indicate that cosmic-ray electrons are accelerated on $\sim$Mpc scales. However, protons appear to be accelerated less efficiently since their associated hadronic $\gamma$-ray…

High Energy Astrophysical Phenomena · Physics 2016-12-14 Denis Wittor , Franco Vazza , Marcus Brüggen

Recent results on the radio emission from galaxy clusters are reviewed, with emphasis both on the radio galaxies and on the diffuse radio emission from the intracluster medium. We show that the formation of the tailed morphology in cluster…

Astrophysics · Physics 2007-05-23 Luigina Feretti

The polarized synchrotron data of the northern C-BASS survey show a surprisingly low linear polarization fraction, $\Pi\simeq 3\%$, while the magnetic field polarization features coherent structures over rather large angular scales. The low…

Astrophysics of Galaxies · Physics 2025-03-26 C. T. Becker , M. Kachelriess

We examine the polarization signal of the cosmic microwave background radiation associated with distant clusters. The polarization is induced by the Thomson scattering of microwave photons with ionized gas of clusters and contains…

Astrophysics · Physics 2016-08-30 Naoki Seto , Misao Sasaki

We report results on deep Jansky Very Large Array A-configuration observations at 22 GHz of the hotspots of the radio galaxies 3C227 and 3C445. Synchrotron emission in the optical on scales up to a few kpc was reported for the four…

High Energy Astrophysical Phenomena · Physics 2020-04-30 M. Orienti , G. Migliori , G. Brunetti , H. Nagai , F. D'Ammando , K. -H. Mack , M. A. Prieto

We report the discovery of a statistically significant radial alignment of cluster galaxies in a sample of 85 X-ray selected clusters observed in the Sloan Digital Sky Survey. The tendency for alignment is a robust feature of our sample and…

Astrophysics · Physics 2009-11-10 M. J. Pereira , J. R. Kuhn

Low-frequency radio observations are revealing an increasing number of diffuse synchrotron sources from galaxy clusters, dominantly in the form of radio halos or radio relics. The existence of this diffuse synchrotron emission indicates the…

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