Radio continuum imaging of far-infrared-luminous QSOs at z > 6

C. L. Carilli, F. Walter, F. Bertoldi, K. M. Menten, X. Fan, G. F. Lewis, Michael A. Strauss, Pierre Cox, A. Beelen, A. Omont, N. Mohan

Research output: Contribution to journalArticlepeer-review

44 Scopus citations


We present sensitive imaging at 1.4 GHz of the two highest redshift far-infrared (FIR) luminous QSOs, SDSS J114816.65+525150.2 (z = 6.42) and SDSS J104845.05+463718.3 (z = 6.2). Radio continuum emission is detected from J1148+5251 with S1.4 = 55 ± 12 μJy, while J1048+4637 is marginally detected with S1.4 = 26 ± 12 μJy. Comparison of the radio and FIR luminosities shows that both sources follow the radio-FIR correlation for star-forming galaxies, with implied (massive) star formation rates ∼103 M yr-1, although we cannot rule out as much as 50% of the FIR luminosity being powered by the active galactic nucleus. Five bright (>22 mJy) radio sources are detected within 8′ of J1148+5251. This is a factor of 30 more than expected for a random field. Two sources have SDSS redshifts, including a z = 1.633 radio-loud quasar and a z = 0.05 radio galaxy. However, we do not find evidence for a galaxy cluster in the SDSS data, at least out to z = 0.2. Considering the faint SDSS magnitudes of the remaining radio sources, we conclude that the overdensity of radio sources could either be a statistical fluke or a very large scale structure (>8 Mpc comoving) at z ≥ 1. We also consider the possibility of gravitational lensing by the closest (in angle) bright galaxy in the SDSS data at z = 0.05 and conclude that the galaxy provides negligible magnification.

Original languageEnglish (US)
Pages (from-to)997-1001
Number of pages5
JournalAstronomical Journal
Issue number3 1785
StatePublished - Sep 2004


  • Galaxies: active
  • Galaxies: formation
  • Galaxies: high-redshift
  • Galaxies: starburst
  • Infrared: galaxies
  • Radio continuum: galaxies

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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