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Radio halos are synchrotron radio sources detected in some massive galaxy clusters. Their Mpc-size indicates that (re)acceleration processes are taking place in the host cluster. X-ray catalogues of galaxy clusters have been used in the…

Cosmology and Nongalactic Astrophysics · Physics 2015-10-28 A. Bonafede , H. T. Intema , M. Brüggen , F. Vazza , K. Basu , M. Sommer , H. Ebeling , F. de Gasperin , H. J. A. Röttgering , R. J. van Weeren , R. Cassano

We present the results of observations performed with the Sardinia Radio Telescope (SRT) at 1.3-1.8 GHz of the galaxy cluster CL 0217+70 and a $3^\circ \times 3^\circ$ region around it. We combine the SRT data with archival Very Large Array…

Cosmology and Nongalactic Astrophysics · Physics 2024-12-13 P. Marchegiani , V. Vacca , F. Govoni , M. Murgia , F. Loi , L. Feretti

Radio-to-$\gamma$-ray signals, recently found narrowly confined near the characteristic $2.4R_{500}$ scaled radii of galaxy clusters and groups, have been associated with their virial (structure-formation accretion) shocks based on…

Cosmology and Nongalactic Astrophysics · Physics 2025-11-06 Uri Keshet

We aim to carry out a radio study of the SoUthern Cluster sCale Extended Source Survey (SUCCESS) sample consisting of twenty massive (M$_{500} > 5\times10^{14}$ M$_{\odot}$), nearby (redshift $<0.3$) and southern ($-50^{\circ} < \delta <…

Cosmology and Nongalactic Astrophysics · Physics 2022-06-23 R. Kale , V. Parekh , M. Rahaman , D. C. Joshi , T. Venturi , K. Kolokythas , J. O. Chibueze , S. Sikhosana , D. Pillay , K. Knowles

Cluster mergers leave distinct signatures in the ICM in the form of shocks and diffuse cluster radio sources that provide evidence for the acceleration of relativistic particles. However, the physics of particle acceleration in the ICM is…

Radio relics are Mpc-scale diffuse radio sources at the peripheries of galaxy clusters which are thought to trace outgoing merger shocks. We present XMM-Newton and Suzaku observations of the galaxy cluster Abell 2744 (z=0.306), which reveal…

High Energy Astrophysical Phenomena · Physics 2016-07-15 Dominique Eckert , Mathilde Jauzac , Franco Vazza , Matt Owers , Jean-Paul Kneib , Celine Tchernin , Huib Intema , Kenda Knowles

We analyse the feasibility of detecting the polarization of the CMB caused by scattering of the remote temperature quadrupole by galaxy clusters with forthcoming CMB polarization surveys. For low-redshift clusters, the signal is strongly…

Cosmology and Nongalactic Astrophysics · Physics 2014-09-24 Alex Hall , Anthony Challinor

Hierarchical models of structure formation predict that galaxy clusters grow via mergers of smaller clusters and galaxy groups, as well as through continuous accretion of gas. MACS J0717.5+3745 is an X-ray luminous and complex merging…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 R. J. van Weeren , H. J. A. Rottgering , M. Bruggen , A. Cohen

We summarize the current state of polarization observations of Sagittarius A*, the compact radio source and supermassive black hole candidate in the Galactic Center. These observations are providing new tools for understanding accretion…

Astrophysics · Physics 2007-05-23 Geoffrey C. Bower

Magnetic fields are ubiquitous in galaxy clusters, yet their radial profile, power spectrum, and connection to host cluster properties are poorly known. Merging galaxy clusters hosting diffuse polarized emission in the form of radio relics…

Astrophysics of Galaxies · Physics 2021-02-03 C. Stuardi , A. Bonafede , L. Lovisari , P. Domínguez-Fernández , F. Vazza , M. Brüggen , R. J. van Weeren , F. de Gasperin

We completed observations with the Effelsberg 100-m radio telescope to measure the polarised emission from a complete sample of Compact Steep-Spectrum sources. We observed the sources at four different frequencies. We complemented these…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 F. Mantovani , K. -H. Mack , F. M. Montenegro-Montes , A. Rossetti , A. Kraus

We report here multi-epoch, multi-frequency observations of the circular polarization in Sagittarius A*, the compact radio source in the Galactic Center. Data taken from the VLA archive indicate that the fractional circular polarization at…

Astrophysics · Physics 2009-11-07 Geoffrey C. Bower , Heino Falcke , Robert J. Sault , Donald C. Backer

The nature of radio outflows in radio-quiet AGN remains poorly understood. In this study, we present kpc-scale polarization observations of the Seyfert galaxy NGC\,4151 using the Karl G. Jansky Very Large Array (VLA) in B-array at 3 and 10…

Astrophysics of Galaxies · Physics 2026-01-23 Salmoli Ghosh , P. Kharb , E. Costantini , J. Gallimore , D. Williams-Baldwin , M. Mehdipour

Galaxy clusters undergo mergers that can generate extended radio sources called radio relics. Radio relics are the consequence of merger-induced shocks that propagate in the intra cluster medium (ICM). In this paper we analyse the radio,…

Cosmology and Nongalactic Astrophysics · Physics 2016-12-21 F. de Gasperin , H. T. Intema , J. Ridl , M. Salvato , R. van Weeren , A. Bonafede , J. Greiner , R. Cassano , M. Bruggen

We present new high sensitivity observations of the radio relic in A521 carried out with the Giant Metrewave Radio Telescope at 327 MHz and with the Very Large Array at 4.9 and 8.5 GHz. We imaged the relic at these frequencies and carried…

Non-thermal radio emission from cosmic ray electrons in the vicinity of merging galaxy clusters is an important tracer of cluster merger activity, and is the result of complex physical processes that involve magnetic fields, particle…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-12 Samuel W. Skillman , Hao Xu , Eric J. Hallman , Brian W. O'Shea , Jack O. Burns , Hui Li , David C. Collins , Michael L. Norman

We characterised and studied, in the radio band, a sample of candidates of high Rotation Measure (RM). These point-like objects show a strong depolarisation at 21cm. This feature suggests the presence of a very dense medium surrounding them…

Astrophysics of Galaxies · Physics 2016-02-17 Alice Pasetto , Alex Kraus , Karl-Heinz Mack , Gabriele Bruni , Carlos Carrasco-Gonzalez

Synchrotron radio halos at the center of merging galaxy clusters provide the most spectacular and direct evidence of the presence of relativistic particles and magnetic fields associated with the intracluster medium. The study of polarized…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-15 F. Govoni , M. Murgia , H. Xu , H. Li , M. L. Norman , L. Feretti , G. Giovannini , V. Vacca

We present newly discovered radio emission in the galaxy cluster Abell 2443 which is (1) diffuse, (2) extremely steep spectrum, (3) offset from the cluster center, (4) of irregular morphology and (5) not clearly associated with any of the…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-27 Aaron Cohen , Tracy E Clarke

Radio galaxies are uniquely useful as probes of large-scale structure as their uniform identification with giant elliptical galaxies out to high redshift means that the evolution of their bias factor can be predicted. As the initial stage…

Astrophysics · Physics 2009-10-31 Mark Lacy