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Active galactic nuclei (AGN) have been observed as far as redshift z~7. They are crucial in investigating the early Universe as well as the growth of supermassive black holes at their centres. Radio-loud AGN with their jets seen at a small…

星系天体物理 · 物理学 2023-03-20 K. É. Gabányi , S. Belladitta , S. Frey , G. Orosz , L. I. Gurvits , K. Rozgonyi , T. An , H. Cao , Z. Paragi , K. Perger

We have made observations of the associated HI absorption of a high redshift radio galaxy 0902+34 at z=3.395 with the Giant Meterwave Radio Telescope in the $323\pm1$ MHz band. We find a narrow absorption line with a flux density of 11.5…

天体物理学 · 物理学 2009-11-10 P. Chandra , G. Swarup , V. K. Kulkarni , N. G. Kantharia

We report results from a Giant Metrewave Radio Telescope search for "associated" redshifted HI 21cm absorption from 24 active galactic nuclei (AGNs), at $1.1 < z < 3.6$, selected from the Caltech-Jodrell Bank Flat-spectrum (CJF) sample. 22…

星系天体物理 · 物理学 2015-12-09 J. N. H. S. Aditya , Nissim Kanekar , Sushma Kurapati

We report the results of our observations of HI absorption towards the central region of the rejuvenated radio galaxy 4C29.30 (J0840+2949) with the Giant Metrewave Radio Telescope (GMRT). The radio source has diffuse, extended emission with…

宇宙学与河外天体物理 · 物理学 2015-05-14 Yogesh Chandola , D. J. Saikia , Neeraj Gupta

The IRAS Revised Bright Galaxy Sample (RBGS) comprises galaxies and unresolved mergers stronger than $S = 5.24$ Jy at $\lambda = 60~\mu\mathrm{m}$ with galactic latitudes $\vert b \vert > 5^\circ$. Nearly all are dusty star-forming galaxies…

星系天体物理 · 物理学 2021-11-24 J. J. Condon , W. D. Cotton , T. Jarrett , L Marchetti , A. M. Matthews , T. Mauch , M. E. Moloko

In this paper we present follow-up optical observations of Ultra Steep Spectrum sources that were found by matching 150 MHz GMRT sources with either the 74 MHz VLSS or the 1400 MHz NVSS. These sources are possibly high-redshift radio…

宇宙学与河外天体物理 · 物理学 2011-10-12 Samuel J. George , Ian R. Stevens

We report the 888 MHz radio detection in the Rapid ASKAP Continuum Survey (RACS) of VIK J2318$-$3113, a $z$=6.44 quasar. Its radio luminosity (1.2 $\times 10^{26}$ W Hz$^{-1}$ at 5 GHz) compared to the optical luminosity (1.8 $\times…

星系天体物理 · 物理学 2021-03-24 L. Ighina , S. Belladitta , A. Caccianiga , J. W. Broderick , G. Drouart , A. Moretti , N. Seymour

A significant minority of high redshift radio galaxy (HzRG) candidates show extremely red broad band colours and remain undetected in emission lines after optical `discovery' spectroscopy. In this paper we present deep GTC optical imaging…

We present high-resolution radio observations of a sample of 65 radio sources at low Galactic latitudes. The sources were all observed at 5 GHz with the Very Large Array A-array. MERLIN observations at 5 GHz of the ultracompact HII region…

天体物理学 · 物理学 2009-11-10 D. J. Saikia , P. Thomasson , S. Roy , A. Pedlar , T. W. B. Muxlow

Radio observations offer a dust-independent probe of star formation and active galactic nucleus (AGN) activity, but sufficiently deep data are required to access the crossover luminosity between these processes at high redshift ($z>4.5$).…

We report a uGMRT detection of HI 21-cm absorption associated with the radio source 8C 0604+728, at $z = 3.52965$. The source is at the highest redshift at which associated HI 21-cm absorption has been discovered to date, surpassing earlier…

星系天体物理 · 物理学 2020-11-20 J. N. H. S. Aditya , Regina Jorgenson , Vishal Joshi , Veeresh Singh , Tao An , Yogesh Chandola

We have discovered a number of relatively strong radio sources in the field-of-view of SDSS galaxy clusters which present no optical counterparts down to the magnitude limits of the SDSS. The optically faint radio sources appear as…

宇宙学与河外天体物理 · 物理学 2015-05-30 Mercedes E. Filho , Jarle Brinchmann , Catarina Lobo , Sonia Antón

We report the results of a visual inspection of images of the Rapid ASKAP Continuum Survey (RACS) in search of extended radio galaxies (ERG) that reach or exceed linear sizes on the order of one Megaparsec. We searched a contiguous area of…

星系天体物理 · 物理学 2021-11-18 Heinz Andernach , Eric F. Jiménez-Andrade , Anthony G. Willis

Observations of fluctuations in the redshifted 21 cm radiation from neautral hydrogen (HI) are perceived to be an important future probe of the universe at high redshifts. Under the assumption that at redshifts z less than 6…

天体物理学 · 物理学 2009-11-13 Sk. Saiyad Ali , Somnath Bharadwaj , Sanjay K. Pandey

We present high-resolution interferometric Submillimeter Array (SMA) imaging at 890 microns (~2" resolution) of two millimeter selected galaxies -- MMJ100015+021549 and MMJ100047+021021 -- discovered with the Max-Planck Millimeter Bolometer…

宇宙学与河外天体物理 · 物理学 2015-05-19 M. Aravena , J. D. Younger , G. G. Fazio , M. Gurwell , D. Espada , F. Bertoldi , P. Capak , D. Wilner

We have observed the DEEP2 galaxies using the Giant Meterwave Radio Telescope in the frequency band of 610 MHz. There are $\simeq 400$ galaxies in the redshift range $1.24 < z < 1.36$ and within the field of view $\simeq 44'$, of the GMRT…

宇宙学与河外天体物理 · 物理学 2013-05-20 Shiv K. Sethi , K. S. Dwarakanath , Chandrashekar Murugesan

We report the first detections of associated H{\sc i} 21\,cm absorption in Gigahertz-peaked-spectrum (GPS) sources at high redshifts, $z > 1$, using the Giant Metrewave Radio Telescope (GMRT). Our GMRT search for associated H{\sc i} 21\,cm…

星系天体物理 · 物理学 2017-10-25 J. N. H. S. Aditya , Nissim Kanekar

The radio bright zone (RBZ) at the Galactic center has been observed with the JVLA in the A, B and C array configurations at 5.5 and 9 GHz. With a procedure for high-dynamic range imaging developed on CASA, we constructed deep images a…

高能天体物理现象 · 物理学 2020-10-26 Jun-Hui Zhao , Mark R. Morris , W. M. Goss

I report detections of four new HI 21-cm absorbers associated with sources at intermediate redshifts, 0.7 < z < 1.0. The sources are part of a sample of 11 radio-loud galaxies, all at 0.7 < z < 1.0, that were searched for associated HI…

星系天体物理 · 物理学 2018-11-28 J. N. H. S. Aditya

Recent observations by the James Webb Space Telescope (JWST) have revealed a puzzling population of optically red and compact galaxies with peculiar "V"-shaped spectra at high redshift, known as "Little Red Dots" (LRDs). Until now, most…