GB 1508+5714 : a radio-loud quasar with Z = 4.30 and the space density of high-redshift, radio-loud quasars.
Abstract
We report the discovery of a radio-loud quasar with a redshift of 4.30. This object, which is the first radio-selected quasar with a redshift greater than 4, was discovered during an observational investigation into the evolution of the luminosity function of radio-loud quasars. Here we describe results based on a sample of ~300 flat-spectrum radio sources with S_5 GHz_ > 200 mJy. In this study, rather than carry out an indiscriminate redshift campaign on all the radio sources, we have used the APM POSS catalogue to pre-select a subset of stellar-like optical counterparts with red optical colours. Such a subsample is expected to contain a high fraction of high-redshift quasars. 10 of the ~300 sources were selected for follow-up optical spectroscopy, and three of these are identified as quasars with redshifts greater than 3.0. One of the radio sources, GB1508+5714, is a quasar with z = 4.30 and m(R)~19.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- April 1995
- DOI:
- 10.1093/mnras/273.1.L63
- arXiv:
- arXiv:astro-ph/9502071
- Bibcode:
- 1995MNRAS.273L..63H
- Keywords:
-
- Astrophysics
- E-Print:
- 5 pages, one uuencoded compressed postscipt file (created with uufiles) including figures. MNRAS Letter, in press.