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Magnetospheric processes seen in gas-giants such as aurorae and circularly-polarized cyclotron maser radio emission have been detected from some brown dwarfs. However, previous radio observations targeted known brown dwarfs discovered via…

Recent advances in high-sensitivity radio observations have uncovered a population of faint, ultra-steep-spectrum sources in galaxy clusters, commonly known as radio phoenixes. However, their observational classification remains poorly…

Cosmology and Nongalactic Astrophysics · Physics 2025-10-28 Nasmi S Anand , Swarna Chatterjee , Ramij Raja , Majidul Rahaman , Abhirup Datta

With Australia Telescope Compact Array observations, we detect a highly elongated Mpc-scale diffuse radio source on the eastern periphery of the Bullet cluster 1E0657-55.8, which we argue has the positional, spectral and polarimetric…

High Energy Astrophysical Phenomena · Physics 2016-03-23 Timothy W. Shimwell , Maxim Markevitch , Shea Brown , Luigina Feretti , B. M. Gaensler , M. Johnston-Hollitt , Craig Lage , Raghav Srinivasan

Recent X-ray observations of the rich galaxy cluster CL 0939+4713 at z = 0.41 with the ROSAT/HRI as well as with the ASCA/GIS and ASCA/SIS are presented and analysed. With the high resolution imaging data we confirm and extend the earlier…

Astrophysics · Physics 2007-05-23 S. Schindler , P. Belloni , Y. Ikebe , M. Hattori , J. Wambsganss , Y. Tanaka

Mergers of galaxy clusters are among the most energetic events in the Universe. These events have significant impact on the intra-cluster medium, depositing vast amounts of energy - often in the form of shocks - as well as heavily…

Cosmology and Nongalactic Astrophysics · Physics 2017-01-11 C. J. Riseley , A. M. M. Scaife , M. W. Wise , A. O. Clarke

We present optical spectropolarimetric and imaging polarimetric observations of four high-redshift radio galaxies (HzRGs) obtained with the 10-m Keck I telescope. A broad Mg II emission line is detected in the total and polarized flux…

SMM J04542-0301 is an extended (~1 arcmin) sub-mm source located near the core of the cluster MS0451.6-0305. It has been suggested that part of its emission arises from the interaction between a LBG and two EROs at z~2.9 that are…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-14 A. Berciano Alba , L. V. E. Koopmans , M. A. Garrett , O. Wucknitz , M. Limousin

We explore the possibility of detecting the excess of the cosmic radio background (CRB) toward galaxy clusters due to its Compton scattering by electrons of the hot intergalactic gas. When mapping the background fluctuations at frequencies…

High Energy Astrophysical Phenomena · Physics 2024-08-06 S. A. Grebenev , R. A. Sunyaev

High-resolution radio observations of cluster radio relics often show complex spatial and spectral features. However, it is not clear what these features reveal about the underlying magnetic field properties. We performed three-dimensional…

High Energy Astrophysical Phenomena · Physics 2020-10-21 P. Domínguez-Fernández , M. Brüggen , F. Vazza , W. E. Banda-Barragán , K. Rajpurohit , A. Mignone , D. Mukherjee , B. Vaidya

We report on full-polarization radio observations of the Perseus cluster (Abell 426) using the Westerbork Synthesis Radio Telescope (WSRT) at wavelengths from 81-95 cm. We have employed a novel technique, Rotation Measure synthesis…

Astrophysics · Physics 2009-11-13 A. G. de Bruyn , M. A. Brentjens

Giant radio halos are diffuse, Mpc-scale, synchrotron sources located in the central regions of galaxy clusters and provide the most relevant example of cluster non-thermal activity. Radio and X-ray surveys allow to investigate the…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-14 G. Brunetti , R. Cassano , K. Dolag , G. Setti

Large-scale magnetic fields reveal themselves through diffuse synchrotron sources observed in galaxy clusters such as radio halos. Total intensity filaments of these sources have been observed in polarization as well, but only in three…

We present radio observations of the galaxy cluster Abell S1136 at 888 MHz, using the Australian Square Kilometre Array Pathfinder radio telescope, as part of the Evolutionary Map of the Universe Early Science program. We compare these…

The presence of non-thermal electrons and large scale magnetic fields in the intra-cluster medium (ICM) is known through the detection of mega-parsec (Mpc) scale diffuse radio synchrotron emission. Although a significant amount of progress…

High Energy Astrophysical Phenomena · Physics 2020-11-04 Ramij Raja , Majidul Rahaman , Abhirup Datta , Reinout J. van Weeren , Huib T. Intema , Surajit Paul

Multi-wavelength VLA observations of two extended radio galaxies, 0235-197 and 1203+043 are presented. There is some evidence from earlier studies that these two sources exhibit low frequency (<1 GHz) variability. This work shows that both…

Astrophysics · Physics 2009-10-31 W. Junor , F. Mantovani , R. Morganti , L. Padrielli

A number of radio observations have revealed the presence of large synchrotron-emitting sources associated with the intra-cluster medium. There is strong observational evidence that the emitting particles have been (re-)accelerated by…

Radio relics are diffuse extended synchrotron sources that originate from shock fronts induced by galaxy cluster mergers. The actual particle acceleration mechanism at the shock fronts is still under debate. The galaxy cluster 1RXS…

High Energy Astrophysical Phenomena · Physics 2020-04-15 K. Rajpurohit , M. Hoeft , F. Vazza , L. Rudnick , R. J. van Weeren , D. Wittor , A. Drabent , M. Brienza , F. Loi , E. Bonnassieux , N. Locatelli , R. Kale , C. Dumba

The bright polarized synchrotron emission, away from the Galactic plane, originates mostly from filamentary structures. We implement a filament finder algorithm which allows the detection of bright elongated structures in polarized…

Cosmology and Nongalactic Astrophysics · Physics 2023-04-26 F. A. Martire , A. J. Banday , E. Martínez-González , R. B. Barreiro

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

We present deep, multiwavelength radio observations of SpARCS104922.6+564032.5, a z = 1.71 galaxy cluster with a starbusting core. Observations were made with the Karl G. Jansky Very Large Array (JVLA) in 3 bands: 1-2 GHz, 4-8 GHz and 8-12…