A search for distant radio galaxies from SUMSS and NVSS - II. Optical spectroscopy

作者：De Breuck C^*; Klamer I; Johnston H; Hunstead RW; Bryant J; Rocca Volmerange B; Sadler EM

来源：Monthly Notices of the Royal Astronomical Society, 2006, 366(1): 58-72.

DOI：10.1111/j.1365-2966.2005.09799.x

• surveys
• galaxies : active
• galaxies : high-redshift
• radio continuum : galaxies
• radio continuum : general

This is the second in a series of papers presenting observations and results for a sample of 76 ultrasteep-spectrum (USS) radio sources in the Southern hemisphere designed to find galaxies at high redshift. Here, we focus on the optical spectroscopy programme for 53 galaxies in the sample. We report 35 spectroscopic redshifts, based on observations with the Very Large Telescope (VLT), the New Technology Telescope (NTT) and the 2.3-m telescope of the Australian National University (ANU); they include five radio galaxies with z > 3. Spectroscopic redshifts for the remaining 18 galaxies could not be confirmed: three are occulted by Galactic stars, eight show continuum emission but no discernible spectral lines, whilst the remaining seven galaxies are undetected in medium-deep VLT integrations. The latter are either at very high redshift (z greater than or similar to 7) or heavily obscured by dust. A discussion of the efficiency of the USS technique is presented. Based on the similar space density of z > 3 radio galaxies in our sample compared with other USS-selected samples, we argue that USS selection at 843-1400 MHz is an efficient and reliable technique for finding distant radio galaxies.

• 出版日期2006-2-11