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Paper: Radio AGN Surveys
Volume: 284, AGN Surveys, IAU Colloquium 184
Page: 275
Authors: De Breuck, Carlos; van Breugel, Wil; Röttgering, Huub; Carilli, C.
Abstract: We have constructed a sample of 669 Ultra Steep Spectrum radio sources to search for High Redshift Radio Galaxies, which are identified with the most luminous and massive galaxies at z > 1. This sample is based on the new radio surveys such as the 325 MHz WENSS, the 365 MHz Texas, and the 1.4 GHz FIRST and NVSS. We show the efficiency of this well-established technique, which is based mainly on the k-correction of the concave radio spectrum. K-band imaging with Keck and CTIO of this sample identifies 94% of the sources, and optical spectroscopy with 3-10m telescopes allows the redshift determination of 75% of these sources. However, in 6 sources, the AGN appears to be heavily obscured, preventing the redshift determination.
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