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The correlation between radio spectral index and redshift has been exploited to discover high redshift radio galaxies, but its underlying cause is unclear. It is crucial to characterise the particle acceleration and loss mechanisms in high…

Low-frequency radio surveys allow in-depth studies and new analyses of classes of sources previously known and characterised only in other bands. In recent years, low radio frequency observations of blazars have been available thanks to new…

星系天体物理 · 物理学 2020-01-08 Daniele d'Antonio , Marcello Giroletti , Gabriele Giovannini , Alessandro Maini

We discuss the properties of the sources in the CLASS Blazar survey which aims at the selection of low radio power (P(5GHz)<10^25 W Hz^-1) blazars. We use VLA data from available catalogues and from our own observations to constrain the…

天体物理学 · 物理学 2009-11-10 A. Caccianiga , M. J. M. Marcha

At bright radio powers ($P_{\rm 1.4 GHz} > 10^{25}$ W/Hz) the space density of the most powerful sources peaks at higher redshift than that of their weaker counterparts. This paper establishes whether this luminosity-dependent evolution…

星系天体物理 · 物理学 2015-09-16 E. E. Rigby , J. Argyle , P. N. Best , D. Rosario , H. J. A. Röttgering

Keck spectropolarimetry, giving spectral coverage from Ly-$\alpha$ to beyond CIII], and HST imaging of a sample of powerful radio galaxies with $z\sim2.5$\ has been obtained. These data are giving us a clear picture of the nature of the…

天体物理学 · 物理学 2007-05-23 R A E Fosbury , J Vernet , M Villar-Martin , M H Cohen , A Cimatti , S di Serego Alighieri , P J McCarthy

We present an investigation of the properties of the extended Ly$\alpha$ halo and the large-scale \ion{H}{I} absorbing structures associated with 5 high-redshift radio galaxies at z $>$ 2, using the Goodman long-slit spectrograph on the…

星系天体物理 · 物理学 2018-09-11 M. Silva , A. Humphrey , P. Lagos , R. Guimarães , T. Scott , P. Papaderos , S. G. Morais

Study of high-redshift radio galaxies (HzRGs) can shed light on the active galactic nuclei (AGNs) evolution in massive elliptical galaxies. The vast majority of observed high-redshift AGNs are quasars, and there are very few radio galaxies…

We have conducted an optical/near-infrared study of the environments of radio-loud quasars (RLQs) at redshifts z=0.6-2. In this paper we discuss the sample selection and observations for the z=1-2 subsample and the reduction and cataloguing…

天体物理学 · 物理学 2009-10-30 Patrick B. Hall , Richard F. Green , Martin Cohen

Next-generation radio surveys are expected to detect tens of millions of active galactic nuclei (AGN) with a median redshift of z > 1. Beyond targeted surveys, the vast majority of these objects will not have spectroscopic redshifts, whilst…

星系天体物理 · 物理学 2020-11-03 Ross J. Turner , Guillaume Drouart , Nick Seymour , Stanislav S. Shabala

The population of high-redshift radio galaxies (HzRGs) is still poorly studied because only a few of these objects are currently known. We here present the results of a pilot project of spectroscopic identification of HzRG candidates. The…

In this paper we review the present status and implications of H-alpha surveys at various redshifts. With the advent of sensitive wide-format near-infrared detectors on large telescopes, deep and extensive H-alpha surveys are now feasible…

天体物理学 · 物理学 2017-01-25 Paul P. van der Werf , Alan F. M. Moorwood , Lin Yan

We present deep radio maps from the Very Large Array (VLA) for 16 sources detected in a sub-millimeter (submm) survey of the distant Universe. Our deep VLA 1.4-GHz maps allow us to identify radio counterparts or place stringent limits…

天体物理学 · 物理学 2009-10-31 Ian Smail , R. J. Ivison , F. N. Owen , A. W. Blain , J. -P. Kneib

A significant fraction of galaxy clusters exhibits cluster wide radio halos. We give a simple prediction of the local and higher redshift radio halo luminosity function (RHLF) on the basis of (i) an observed and a theoretical X-ray cluster…

天体物理学 · 物理学 2009-11-07 Torsten A. Ensslin , Huub Roettgering

Radio continuum emission has the potential to be an extinction-free tracer of star formation. However, the relation between radio continuum luminosity and star formation rate, the radio-SFR relation, is affected by various effects such as…

The Combined EIS-NVSS Survey Of Radio Sources (CENSORS) is a 1.4 GHz radio survey selected from the NRAO VLA Sky Survey (NVSS) and complete to a flux-density of 7.2mJy. It targets the ESO Imaging Survey (EIS) Patch D, which is a 3 by 2…

天体物理学 · 物理学 2009-11-11 M. H. Brookes , P. N. Best , R. Rengelink , H. J. A. Rottgering

While unobscured and radio-quiet active galactic nuclei are regularly being found at redshifts $z > 6$, their obscured and radio-loud counterparts remain elusive. We build upon our successful pilot study, presenting a new sample of…

The radio and far-infrared luminosities of star-forming galaxies are tightly correlated over several orders of magnitude; this is known as the far-infrared radio correlation (FIRC). Previous studies have shown that a host of factors…

We present flux densities and polarization percentages of 159 radio galaxies based on nearly simultaneous VLA observations at four frequencies from 5 to 43GHz. This sample is selected from the high-frequency Australia Telescope 20GHz…

宇宙学与河外天体物理 · 物理学 2015-03-18 Anna Sajina , Bruce Partridge , Tyler Evans , Shannon Stefl , Nicholas Vechik , Steve Myers , Simon Dicker , Phillip Korngut

To explore the high frequency radio spectra of galaxies in clusters, we used NRAO's Very Large Array at four frequencies, 4.9-43 GHz, to observe 139 galaxies in low redshift (z<0.25), X-ray detected, clusters. The clusters were selected…

Context. The Australia Telescope Large Area Survey (ATLAS) aims to image a 7 deg2 region centred on the European Large Area ISO Survey - South 1 (ELAIS-S1) field and the Chandra Deep Field South (CDF-S) at 1.4 GHz with high sensitivity (up…

宇宙学与河外天体物理 · 物理学 2015-12-30 Peter-Christian Zinn , Enno Middelberg , Ray P. Norris , Christopher A. Hales , Minnie Y. Mao , Kate E. Randall