TY - JOUR
T1 - A sample of radio-loud QSOs at redshift ∼ 4
AU - Holt, J.
AU - Benn, C. R.
AU - Vigotti, M.
AU - Pedani, M.
AU - Carballo, R.
AU - González-Serrano, J. I.
AU - Mack, K. H.
AU - García, B.
PY - 2004/3/1
Y1 - 2004/3/1
N2 - We obtained spectra of 60 red, star-like objects (E <18.8) identified with FIRST radio sources, S1.4GHZ>1 mJy. Eight are quasi-stellar objects (QSOs) with redshiftz 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 5 1.4GHz10 mJy are QSOs with z > 3.6. The surface density of E <18.8, S1.4GHZ >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, q 0 = 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).
AB - We obtained spectra of 60 red, star-like objects (E <18.8) identified with FIRST radio sources, S1.4GHZ>1 mJy. Eight are quasi-stellar objects (QSOs) with redshiftz 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 5 1.4GHz10 mJy are QSOs with z > 3.6. The surface density of E <18.8, S1.4GHZ >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, q 0 = 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).
KW - Early Universe
KW - Quasars: emission lines
KW - Quasars: general
KW - Radio continuum: galaxies
U2 - 10.1111/j.1365-2966.2004.07423.x
DO - 10.1111/j.1365-2966.2004.07423.x
M3 - Article
SN - 0035-8711
VL - 348
SP - 857
EP - 865
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 3
ER -