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High red-shift radio galaxies are best searched at low radio frequencies, due to its steep radio spectra. Here we present preliminary results from our programme to search for high red-shift radio galaxies to ~ 10 to 100 times fainter than…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-30 Susanta Kumar Bisoi , C. H. Ishwara-Chandra , S. K. Sirothia , P. Janardhan

We present results from a study of X-shaped sources based on observations using the Giant Metrewave Radio Telescope (GMRT). These observations were motivated by our low frequency study of 3C 223.1 (Lal & Rao 2005), an X-shaped radio source,…

Astrophysics · Physics 2008-11-26 Dharam Vir Lal , A. Pramesh Rao

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

TeV J2032+4130 is the first extended very high energy gamma-ray source, which has remained enigmatic since its discovery, due to the lack of identification. We report here deep radio observations covering the TeV J2032+4130 field and…

Astrophysics · Physics 2009-11-11 Josep M. Paredes , Josep Marti , Ishwara Chandra C. H. , Valenti Bosch-Ramon

In order to understand the possible mechanisms of recurrent jet activity in radio galaxies and quasars, which are still unclear, we have identified such sources with a large range of linear sizes (220 $-$ 917 kpc), and hence time scales of…

Astrophysics of Galaxies · Physics 2019-07-17 S. Nandi , D. J. Saikia , R. Roy , P. Dabhade , Y. Wadadekar , J. Larsson , M. Baes , H. C. Chandola , M. Singh

In this paper, we test the possibility that the structure of the largest radio galaxy J1420-0545 may have been formed by restarted rather than primary jet activity. This hypothesis was motivated by the unusual morphological properties of…

Astrophysics of Galaxies · Physics 2017-11-29 M. Jamrozy , J. Machalski , B. Nikiel-Wroczynski , H. T. Intema

We present a study of the extended radio emission in a sample of 8434 low redshift (z < 0.35) broad line active galactic nuclei (AGN) from the Sloan Digital Sky Survey (SDSS). To calculate the jet and lobe contributions to the total radio…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-20 Stephen E. Rafter , D. Michael Crenshaw , Paul J. Wiita

We report the discovery of J1218+1813, a circular diffuse radio source detected in the Very Large Array (VLA) FIRST survey at 1400 MHz. The source has an angular diameter of approximately one arcminute, corresponding to a physical size of…

Astrophysics of Galaxies · Physics 2025-06-24 Shobha Kumari , Sabyasachi Pal , Souvik Manik

Ultra-steep spectrum (USS) radio sources are good tracers of powerful radio galaxies at $z > 2$. Identification of even a single bright radio galaxy at $z > 6$ can be used to detect redshifted 21cm absorption due to neutral hydrogen in the…

Astrophysics of Galaxies · Physics 2018-01-31 A. Saxena , P. Jagannathan , H. J. A. Röttgering , P. N. Best , H. T. Intema , M. Zhang , K. J. Duncan , C. L. Carilli , G. K. Miley

We detect a new suspected giant radio galaxy (GRG) discovered by KAT-7. The GRG core is identified with the WISE source J013313.50-130330.5, an extragalactic source based on its infrared colors and consistent with a misaligned AGN-type…

Astrophysics of Galaxies · Physics 2015-12-23 S. Colafrancesco , N. Mhlahlo , T. Jarrett , N. Oozeer , P. Marchegiani

We present high-resolution, high-sensitivity upgraded Giant Metrewave Radio Telescope observations of the Coma cluster (A1656) at 250-500 MHz and 550-850 MHz. At 250-500 MHz, 135 sources have extensions $>$ 0.45 arcmin (with…

Using the JVLA, we explored the Galactic center (GC) with a resolution of 0.05" at 33.0 and 44.6 GHz. We detected 64 hyper-compact radio sources (HCRs) in the central parsec. The dense group of HCRs can be divided into three spectral types:…

Astrophysics of Galaxies · Physics 2022-03-09 Jun-Hui Zhao , Mark R. Morris , W. M. Goss

We study the morphology of the radio emission of giant radio galaxies (GRGs), a rare type of active galaxies, in order to find new clues for the reasons of their large size. Using radio images from two sky surveys at 1.4 GHz we quantified…

Astrophysics of Galaxies · Physics 2016-10-11 Elizabeth López Vázquez , Heinz Andernach

We have conducted a deep radio survey with the Very Large Array at 1.4 GHz of a region containing the Hubble Deep Field. This survey overlaps previous observations at 8.5 GHz allowing us to investigate the radio spectral properties of…

Astrophysics · Physics 2009-10-31 E. A. Richards

We present the results of Giant Metrewave Radio Telescope (GMRT) observations to detect H{\sc i} in absorption towards the cores of a sample of radio galaxies. From observations of a sample of 16 sources, we detect H{\sc i} in absorption…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-12 Yogesh Chandola , Neeraj Gupta , D. J. Saikia

A comparison of the recent LOFAR 144 MHz map of the radio source 3C 223.1 (J094124.028+394441.95) with the VLA maps at 4.9 GHz and 8.3 GHz that we built based on archival data, establishes this X-shaped radio galaxy (XRG) as a singularly…

Astrophysics of Galaxies · Physics 2022-07-27 Gopal-Krishna , Pratik Dabhade

We present the results from a pilot study with the Karl G. Jansky Very Large Array (JVLA) to determine the radio morphologies of extended radio sources and the properties of their host-galaxies in 10 massive galaxy clusters at z~1, an epoch…

In this paper we present new high sensitivity 153 MHz Giant Meterwave Radio Telescope follow-up observations of the diffuse steep spectrum cluster radio sources in the galaxy clusters Abell 521, Abell 697, Abell 1682. Abell 521 hosts a…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-12 G. Macario , T. Venturi , H. T. Intema , D. Dallacasa , G. Brunetti , R. Cassano , S. Giacintucci , C. Ferrari , C. H. Ishwara-Chandra , R. Athreya

We present the results from studying 140 radio sources in the GLEAM (GaLactic and Extragalactic All-sky MWA [Murchison Widefield Array]) 4-Jy (G4Jy) Sample. These sources were followed-up with MeerKAT to assess their radio morphology and…

We present a study of the peculiar radio galaxy B 1834+620. It is characterised by the presence of a 420-kpc large edge-brightened radio source which is situated within, and well aligned with, a larger (1.66 Mpc) radio source. Both sources…

Astrophysics · Physics 2009-10-31 Arno P. Schoenmakers , A. G. de Bruyn , H. J. A. Rottgering , H. van der Laan