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Cross-matching catalogues from radio surveys to catalogues of sources at other wavelengths is extremely hard, because radio sources are often extended, often consist of several spatially separated components, and often no radio component is…

天体物理仪器与方法 · 物理学 2020-08-13 Dongwei Fan , Tamás Budavári , Ray P. Norris , Amitabh Basu

Upcoming radio surveys will probe the sky with unprecedented depth and sky coverage, enabling a broad range of cosmological and astrophysical applications, as well as powerful synergies with experiments at other wavelengths. The preparation…

Baldwin (1982) wrote that \emph{the distribution of sources in the radio luminosity, $P$, overall physical size, $D$, diagram} could be considered as \emph{the radio astronomer's $H-R$ diagram}. However, unlike the case of stars, not only…

星系天体物理 · 物理学 2016-03-16 Manel Perucho

We discuss the ``angular size - redshift'' relation for compact radio sources distributed over a wide range of redshifts 0.01 < z < 4.73. Our study is based on a sample of 330 5 GHz VLBI contour maps taken from the literature. Unlike…

天体物理学 · 物理学 2007-05-23 L. I. Gurvits , K. I. Kellermann , S. Frey

We report a discovery of proto-cluster candidates around high redshift radio galaxies at z~2.5 on the basis of clear statistical excess of colour-selected galaxies around them seen in the deep near-infrared imaging data obtained with CISCO…

天体物理学 · 物理学 2009-11-11 Masaru Kajisawa , Tadayuki Kodama , Ichi Tanaka , Toru Yamada , Richard Bower

We examine the possibility that a claimed dependence of the FR 1/2 break value in radio luminosity on the absolute magnitude of the optical host galaxy could be due to the Malmquist bias, where a redshift-luminosity correlation appears in a…

星系天体物理 · 物理学 2014-06-18 Ashok K. Singal , Kamlesh Rajpurohit

The radio skies remain mostly unobserved when it comes to transient phenomena. The direct detection of gravitational waves will mark a major milestone of modern astronomy, as an entirely new window will open on the universe. Two apparently…

广义相对论与量子宇宙学 · 物理学 2015-05-14 V. Predoi , J. Clark , T. Creighton , E. Daw , S. Fairhurst , I. S. Heng , J. Kanner , T. Regimbau , P. Shawhan , X. Siemens , P. Sutton , A. Vecchio , D. White , G. Woan

We show how the XXL multiwavelength survey can be used to shed light on radio galaxies and their environment. Two prominent radio galaxies were identified in a visual examination of the mosaic of XXL-North obtained with the Giant Metrewave…

In order to trace the instantaneous star formation rate at high redshift, and hence help understanding the relation between the different emission mechanisms related to star formation, we combine the recent 4 Ms Chandra X-ray data and the…

A Square Kilometer Array radio telescope will detect tens of thousands of galaxies per square degree in the 21cm emission line of neutral hydrogen. The telescope will be sensitive to ordinary galaxy populations at redshifts z>3 when the…

天体物理学 · 物理学 2016-08-30 F. H. Briggs

We present an analysis of the optical spectra of a volume-limited sample of 375 radio galaxies at redshift 0.4<z<0.7 from the 2dF-SDSS Luminous Red Galaxy and QSO (2SLAQ) redshift survey. We investigate the evolution of the stellar…

Giant radio sources form the linear size extreme of the extra-galactic radio source population. Using the WENSS survey, we have selected a complete sample of these sources. We have investigated the properties of their radio structures. We…

To properly understand the evolution of high-redshift galaxy clusters, both passive and star-forming galaxies have to be considered. Here we study the clustering environment of 21 radio galaxies and quasars at 1<z<2.5 from the third…

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…

宇宙学与河外天体物理 · 物理学 2015-05-30 Susanta Kumar Bisoi , C. H. Ishwara-Chandra , S. K. Sirothia , P. Janardhan

We summarize observations of the properties of powerful radio galaxies and their environments from z = 0 to 5. These data show that some high redshift radio galaxies inhabit regions of gas and galaxy over-densities indicative of…

Forthcoming astronomical surveys are expected to detect new sources in such large numbers that measuring their spectroscopic redshift measurements will be not be practical. Thus, there is much interest in using machine learning to yield the…

宇宙学与河外天体物理 · 物理学 2022-03-14 S. J. Curran

This paper introduces a new program to find high-redshift radio galaxies in the southern hemisphere through ultra-steep spectrum (USS) selection. We define a sample of 234 USS radio sources with spectral indices alpha_408^843 < -1.0 and…

天体物理学 · 物理学 2009-11-13 J. W. Broderick , J. J. Bryant , R. W. Hunstead , E. M. Sadler , T. Murphy

The correlation between radio spectral index and redshift has long been used to identify high redshift radio galaxies, but its cause is unknown. Traditional explanations invoke either $(i)$ intrinsic relations between spectral index and…

星系天体物理 · 物理学 2018-08-08 Leah K. Morabito , Jeremy J. Harwood

We have observed a small sample of powerful double radio sources (radio galaxies and quasars) at frequencies around 90 GHz with the BIMA millimetre array, with the intention of constraining the resolved high-frequency spectra of radio…

天体物理学 · 物理学 2009-11-13 M. J. Hardcastle , L. W. Looney

From a statistically complete sample of 188 radio galaxies in Abell clusters, we examine the radio/optical correlations, the FR I/II division, and the univariate and bivariate luminosity functions. As suggested by Owen (1993), the FR I/II…

天体物理学 · 物理学 2008-11-26 Michael J. Ledlow , Frazer N. Owen