2003/11/05 by J. Holt, C. R. Benn, M. Vigotti +8
Physics and Astronomy · #Astrophysics and Star Formation Studies #Galaxies: Formation, Evolution, Phenomena #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1111/j.1365-2966.2004.07423.x
published as Mon.Not.Roy.Astron.Soc. 348 (2004) 857 · Accepted for publication in MNRAS, 9 pages, Latex, 5 postscript figures, 1 landscape table (postscript)
arxiv created 2003/11/05 · openalex publication_date 2004/02/20 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We obtained spectra of 60 red, star-like objects (E < 18.8) identified with FIRST radio sources, S1.4 GHz > 1 mJy. Eight are quasi-stellar objects (QSOs) with redshift z > 3.6. Combined with our earlier pilot search, our sample of 121 candidates yields a total of 18 z > 3.6 QSOs (10 of these with z > 4.0). 8 per cent of candidates with S1.4 GHz< 10 mJy and 37 per cent of candidates with S1.4 GHz> 10 mJy are QSOs with z > 3.6. The surface density of E < 18.8, S1.4 GHz > 1 mJy, z > 4 QSOs is 0.003 deg−2. This is currently the only well-defined sample of radio-loud QSOs at z≈ 4 selected independently of radio spectral index. The QSOs are highly luminous in the optical (eight have MB < −28, q0= 0.5, H0= 50 km s−1 Mpc−1). The SEDs are as varied as those seen in optical searches for high-redshift QSOs, but the fraction of objects with weak (strongly self-absorbed) Lyα emission is marginally higher (3 out of 18) than for high-redshift QSOs from SDSS (5 out of 96).