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Recent observations show a population of active galaxies with milliarcseconds offsets between optical and radio emission. Such offsets can be an indication of extreme phenomena associated with supermassive black holes including relativistic…

Astrophysics of Galaxies · Physics 2017-09-20 Anna Barnacka

Odd Radio Circles (ORCs) are a class of low surface brightness, circular objects approximately one arcminute in diameter. ORCs were recently discovered in the Australian Square Kilometre Array Pathfinder (ASKAP) data, and subsequently…

Using a combination of near-infrared and optical photometry, along with multi-object spectroscopy, we have confirmed the existence of a high-redshift cluster of galxies at z = 0.96. The cluster was found using a wide-angle tailed radio…

We report the discovery of a transient radio source 2.7 arcsec (0.1 pc projected distance) South of the Galactic Center massive black hole, Sagittarius A*. The source flared with a peak of at least 80 mJy in March 2004. The source was…

We present a systematic search for two types of very unusual astronomical objects: Galactic stars and spiral galaxies with double radio lobes, i.e. radio emission on opposite sides of the optical object, suggesting the ejection of jets from…

Astrophysics of Galaxies · Physics 2016-10-11 Abiel Felipe Ortiz Martínez , Heinz Andernach

We have found a peculiar radio source in the field of one of the hottest known clusters of galaxies 1E0657-56. It is slightly extended, highly polarised (54% at 8.8GHz) and has a very steep spectrum, with alpha ~ -1 at 1.3 GHz, steepening…

Astrophysics · Physics 2009-11-07 H. Liang , R. D. Ekers , R. W. Hunstead , E. E. Falco , P. Shaver

Low-frequency radio observations of galaxy clusters are the key to detecting the diffuse extended emission associated with them. The presence and properties of such radio sources in galaxy clusters reveal the existence of magnetic fields on…

Astrophysics · Physics 2009-11-13 R. F. Pizzo , A. G. de Bruyn , L. Feretti , F. Govoni

The radio sky is poorly sampled for rapidly varying transients because of the narrow field-of-view of most imaging radio telescopes at cm and shorter wavelengths. The emergence of sensitive long wavelength observations with intrinsically…

We present high sensitivity radio observations of the merging cluster A521, at a mean redsfhit z=0.247. The observations were carried out with the GMRT at 610 MHz and cover a region of $\sim$1 square degree, with a sensitivity limit of…

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

The scattering diameters of Sgr A* and several nearby OH masers (~ 1" at 1 GHz) indicate that a region of enhanced scattering is along the line of sight to the Galactic center. The scattering diameter of an extragalactic source seen through…

Astrophysics · Physics 2009-10-30 T. Joseph W. Lazio , James M. Cordes

New high quality Keck and ESO images of PKS 1830-211 are presented. Applying a powerful new deconvolution algorithm to these optical and infrared data, both images of the flat spectrum core of the radio source have been identified. An…

Astrophysics · Physics 2009-10-30 F. Courbin , C. Lidman , B. Frye , P. Magain , T. J. Broadhurst , M. A. Pahre , S. G. Djorgovski

We present the results of deep, high-resolution, 5 GHz Expanded Very Large Array (EVLA) observations of the nearby, dwarf lenticular galaxy and intermediate mass black hole candidate (M ~4.5 x 10^5 M_sun), NGC 404. For the first time, radio…

Astrophysics of Galaxies · Physics 2015-06-04 Kristina Nyland , Josh Marvil , Joan Wrobel , Lisa Young , B. Ashley Zauderer

We discover what is in projection the largest known structure of galactic origin: a giant radio galaxy with a projected proper length of $4.99 \pm 0.04\ \mathrm{Mpc}$. The source, named Alcyoneus, was first identified in low-resolution…

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…

Abell 1351 is a massive merging cluster that hosts a giant radio halo and a bright radio edge blended in the halo. In this paper, we present the first ever spectral analysis of this cluster using GMRT 610 MHz and VLA 1.4 GHz archival data…

High Energy Astrophysical Phenomena · Physics 2022-08-17 Swarna Chatterjee , Majidul Rahaman , Abhirup Datta , Ramij Raja

A sample of 129 unresolved radio sources with ultrahigh linear polarization (>30 per cent) has been selected from the NRAO VLA Sky Survey. Such high average linear polarization is unusual in extragalactic sources. Higher resolution…

Astrophysics of Galaxies · Physics 2010-09-21 H. Shi , H. Liang , J. L. Han , R. W. Hunstead

We conducted an extensive identification and analysis of various morphological classes and subclasses of radio galaxies using the latest high-resolution data from the second data release of the LOFAR Two-Metre Sky Survey (LoTSS DR2). This…

Astrophysics of Galaxies · Physics 2026-04-29 Soumen Kumar Bera , Taotao Fang , Tapan K. Sasmal , M. Kunert-Bajraszewska , Xuelei Chen , Soumen Mondal

We present a deep survey of the SuperCLASS super-cluster - a region of sky known to contain five Abell clusters at redshift $z\sim0.2$ - performed using the Arcminute Microkelvin Imager (AMI) Large Array (LA) at 15.5$~$GHz. Our survey…

A small number of double-lobed radio galaxies (17 from our own census of the literature) show an additional pair of low surface brightness `wings', thus forming an overall `X'-shaped appearance. The origin of the wings in these radio…

Astrophysics · Physics 2008-11-26 C. C. Cheung

A measurable fraction ($\sim8$ per cent) of recently discovered arcmin-size circular diffuse radio sources termed as Odd Radio Circles or ORCs can be supernovae remnants in the intragroup medium, within the local group and its immediate…

Astrophysics of Galaxies · Physics 2022-04-12 A. Omar
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