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We present details of a new sample of radio-loud quasars drawn from 0.013 sr of the 7C Redshift Survey. This sample is small (21 quasars) but complete in that every object with an unresolved nucleus and/or broad emission lines with…

Astrophysics · Physics 2016-01-27 Chris J. Willott , Steve Rawlings , Katherine M. Blundell , Mark Lacy

We have combined a survey at 24 microns to 0.3 mJy with the Multiband Imaging Photometer (MIPS) on the Spitzer Space Telescope, a 20 cm A-array VLA survey covering 0.5 deg^2, and an existing 172 ks Chandra X-Ray Observatory exposure to…

The fraction of ionizing photons escaping from high-redshift star-forming galaxies remains a key obstacle in evaluating whether galaxies were the primary agents of cosmic reionization. We previously proposed using the covering fraction of…

Astrophysics of Galaxies · Physics 2016-11-15 Nicha Leethochawalit , Tucker A. Jones , Richard S. Ellis , Daniel P. Stark , Adi Zitrin

We use the 6C** sample to investigate the co-moving space density of powerful, steep-spectrum radio sources. This sample, consisting of 68 objects, has virtually complete K-band photometry and spectroscopic redshifts for 32 per cent of the…

Astrophysics · Physics 2008-11-26 Maria J. Cruz , Matt J. Jarvis , Steve Rawlings , Katherine M. Blundell

We present the results of HI absorption measurements towards a sample of nearby Compact Steep-Spectrum (CSS) and Giga-Hertz Peaked Spectrum (GPS) radio sources, the CORALZ sample, using the Giant Metrewave Radio Telescope (GMRT). We…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-30 Yogesh Chandola , S. K. Sirothia , D. J. Saikia

We present 1.4 and 5 GHz observations taken with the Very Large Array (VLA), and observations at 250 GHz obtained with the Max-Planck millimeter bolometer (MAMBO) at the IRAM 30~m telescope, of ten optically selected Quasi-stellar Objects…

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…

Cold, neutral interstellar gas, the reservoir for star formation, is traced through the absorption of the 21-centimetre continuum radiation by neutral hydrogen (HI). Although detected in one hundred cases in the host galaxies of distant…

Astrophysics of Galaxies · Physics 2024-01-03 S J Curran

We investigate the properties of the environment around 20 powerful radio galaxies and quasars at redshifts between 0.45 and 1. Using XMM-Newton and Chandra observations we probe the spatial distribution and the temperature of the cluster…

Astrophysics · Physics 2009-11-13 Elena Belsole , Diana M. Worrall , Martin J. Hardcastle , Judith H. Croston

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…

Astrophysics · Physics 2009-10-31 Ian Smail , R. J. Ivison , F. N. Owen , A. W. Blain , J. -P. Kneib

We present results from a search of cold neutral gas associated with radio-loud active galactic nuclei (AGNs) at $z < 0.5$ using HI 21-cm absorption measurements from the MeerKAT Absorption Line Survey (MALS). Cross-matching the MALS 1006…

Astrophysics of Galaxies · Physics 2026-04-23 P. P. Deka , N. Gupta , J-. K. Krogager , S. A. Balashev , H. -W. Chen , F. Combes , H. -R. Klöckner , P. Noterdaeme

We present results on a search of heavily obscured active galaxies z>1.7 using the rest-frame 9-20 keV excess for X-ray sources detected in the deep XMM-CDFS survey. Out of 176 sources selected with the conservative detection criteria (>8…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-11 K. Iwasawa , R. Gilli , C. Vignali , A. Comastri , W. N. Brandt , P. Ranalli , F. Vito , N. Cappelluti , F. J. Carrera , S. Falocco , I. Georgantopoulos , V. Mainieri , M. Paolillo

This paper analyses the radio properties of a subsample of optically obscured (R>25.5) galaxies observed at 24um by the Spitzer Space Telescope within the First Look Survey. 96 F[24um]>0.35 mJy objects out of 510 are found to have a radio…

Astrophysics · Physics 2009-11-13 M. Magliocchetti , P. Andreani , M. A. Zwaan

We present the results of a mini-survey for associated HI 21-cm absorption at z < 0.42 with the Giant Metrewave Radio Telescope. Our targets are radio galaxies, selected on the basis that the 1216 Angstrom luminosities are below 10^23 W/Hz,…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-27 S. J. Curran , M. T. Whiting , J. K. Webb , R. Athreya

We are currently undertaking a large survey for redshifted atomic and molecular absorption ... only one clear and one tentative detection were obtained: HI absorption at z = 0.097 in PKS 1555-140 and OH absorption at z =0.126 in PKS…

High-redshift radio sources provide plentiful opportunities for studying the formation and evolution of early galaxies and supermassive black holes. However, the number of known radio-loud active galactic nuclei (AGN) above redshift 4 is…

Astrophysics of Galaxies · Physics 2022-06-29 M. Krezinger , K. Perger , K. É. Gabányi , S. Frey , L. I Gurvits , Zs. Paragi , T. An , Y. Zhang , H. Cao , T. Sbarrato

We present and discuss two catalogues of UV-selected (NUV $< 22.8$ mag) galaxies that lie within a 200 deg$^2$ area of sky covered by the ASKAP FLASH survey and have an impact parameter of less than 20 arcsec to a FLASH radio continuum…

Astrophysics of Galaxies · Physics 2024-11-15 Sophie L. Eden , Elaine M. Sadler , Kevin A. Pimbblet , Elizabeth K. Mahony , Hyein Yoon

We present deep radio observations of the most distant complete quasar sample drawn from the Sloan Digital Sky Survey. Combining our new data with those from literature we obtain a sample which is ~100 per cent complete down to S_1.4GHz =…

Astrophysics · Physics 2009-11-11 M. Cirasuolo , M. Magliocchetti , G. Gentile , A. Celotti , S. Cristiani , L. Danese

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…

Astrophysics of Galaxies · Physics 2015-09-16 E. E. Rigby , J. Argyle , P. N. Best , D. Rosario , H. J. A. Röttgering
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