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We use the observed polarisation properties of a sample of 26 powerful radio galaxies and radio-loud quasars to constrain the conditions in the Faraday screens local to the sources. We adopt the cosmological redshift, low-frequency radio…

Astrophysics · Physics 2009-11-10 J. A. Goodlet , C. R. Kaiser

Based on images from the FIRST survey of the radio sky at 1.4 GHz, the positions of $\sim$5200 hotspots in $\sim$2870 radio galaxies and quasars were compiled, and linear sizes and radio luminosities were derived from the hosts redshifts.…

Astrophysics of Galaxies · Physics 2019-08-28 Pedro A. de la Rosa Valdés , Heinz Andernach

We present basic observational data on the 6C** sample. This is a new sample of radio sources drawn from the 151 MHz 6C survey, which was filtered with radio criteria chosen to optimize the chances of finding radio galaxies at z > 4. The…

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

We have carried out an investigation of the galaxy environments of low redshift ($z<0.3$) QSOs by cross-correlating the positions on the sky of X-ray-selected QSOs/AGN identified in the {\it Einstein} Medium Sensitivity Survey (EMSS) with…

Astrophysics · Physics 2015-06-24 R. J. Smith , B. J. Boyle , S. J. Maddox

We calculate simultaneously the radio and optical luminosity evolutions of quasars, and the distribution in radio loudness R defined as the ratio of radio and optical luminosities, using a flux limited data set containing 636 quasars with…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-27 J. Singal , V. Petrosian , A. Lawrence , L. Stawarz

We use data from the Parkes Half-Jansky Flat-Spectrum (PHJFS) sample (Drinkwater et al. 1997) to constrain the cosmic evolution in the co-moving space density of radio sources in the top decade of the flat-spectrum radio luminosity function…

Astrophysics · Physics 2009-10-31 Matt J. Jarvis , Steve Rawlings

VLA 1.4 GHz (rms noise ~0.012 mJy) and MIPS 24 and 70 micron (rms noise ~0.02 and ~1.7 mJy, respectively) observations covering the 2 square degree COSMOS field are combined with an extensive multi-wavelength data set to study the evolution…

We use the K-z relation for radio galaxies to illustrate why it has proved difficult to obtain definitive cosmological results from studies based entirely on catalogues of the brightest radio sources, e.g. 3C. To improve on this situation…

We derive the scatter in the relationship between redshift and radio-to-submm spectral index, alpha^{350}_{1.4}, using the observed spectral energy distributions of 17 low redshift star forming galaxies. A mean galaxy model is derived,…

Astrophysics · Physics 2009-10-31 C. L. Carilli , M. S. Yun

We present Very Large Array observations at 1.4 and 5 GHz of a sample of 16 quasi-stellar objects (QSOs) at z = 1.78 to 2.71. Half of the chosen quasars are bright at mm wavelengths (250 or 350 GHz) while the other half were not detected at…

Astrophysics · Physics 2008-11-26 A. Petric , C. L. Carilli , F. Bertoldi , A. Beelen , P. Cox , A. Omont

In this paper, we explore how the forthcoming generation of large-scale radio continuum surveys, with the inclusion of some degree of redshift information, can constrain cosmological parameters. By cross-matching these radio surveys with…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-20 Stefano Camera , Mário G. Santos , David J. Bacon , Matt J. Jarvis , Kim McAlpine , Ray P. Norris , Alvise Raccanelli , Huub Röttgering

We present multi-frequency VLA observations of two giant quasars, 0437-244 and 1025-229, from the Molonglo Complete Sample. These sources have well-defined FRII radio structure, possible one-sided jets, no significant depolarization between…

Astrophysics · Physics 2016-08-30 C. H. Ishwara-Chandra , D. J. Saikia

We use high angular resolution data, measured from visibility of sources at the longest baseline of 4500 m of the Australia Telescope Compact Array (ATCA), for the Australia Telescope 20 GHz (AT20G) survey to obtain angular size information…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-04 R. Chhetri , R. D. Ekers , E. K. Mahony , P. A. Jones , M. Massardi , R. Ricci , E. M. Sadler

An angular correlation of low significance (2 sigma) is observed between 0.3 < z < 0.5 QSOs and V < 23 galaxies. Overall, the cross-correlation function between 82 intermediate-redshift (0.3 < z < 0.7), X-ray selected QSOs and V < 24…

Astrophysics · Physics 2009-10-31 R. J. Smith , B. J. Boyle , S. J. Maddox

We apply a cross-correlation technique to infer the $S>3$mJy radio luminosity function (RLF) from the NRAO VLA sky survey (NVSS) to $z\sim3.5$. We measure $\Sigma$ the over density of radio sources around spectroscopically confirmed…

Astrophysics of Galaxies · Physics 2015-08-06 S. Fine , T. Shanks , R. Johnston , M. J. Jarvis , T. Mauch

We re-examine the technique of determining the redshifts of galaxies from the ratio of the submillimeter-to-radio continuum flux densities based on a recently published catalog of 850~$\mu$m sources. We derived the expected variation of…

Astrophysics · Physics 2015-06-24 T. N. Rengarajan , Tsutomu T. Takeuchi

Young radio-loud active galactic nuclei form an important tool to investigate the evolution of extragalactic radio sources. To study the early phases of expanding radio sources, we have constructed CORALZ, a sample of 25 compact…

Astrophysics of Galaxies · Physics 2015-05-13 N. de Vries , I. A. G. Snellen , R. T. Schilizzi , K. -H. Mack , C. R. Kaiser

An analysis of the cluster environments around distant radio galaxies is presented, in particular the results from new NTT deep optical-IR imaging of the fields of radio sources at z ~ 1.6. A net overdensity of K-band galaxies is found,…

Astrophysics · Physics 2007-05-23 P. N. Best , M. D. Lehnert , H. J. A. Rottgering , G. K. Miley

We report on our XMM observations of the high redshift quasars BR 2237--0607 (z=4.558) and BR 0351--1034 (z=4.351), together with 14 other z>4 objects found in the XMM public archive. Contrary to former reports, we do not find high redshift…

Astrophysics · Physics 2010-11-11 D. Grupe , S. Mathur , B. Wilkes , P. Osmer
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