Near-infrared spectroscopy of sdss J0303 - 0019: A Low-luminosity, high-eddington-ratio quasar at z ∼ 6

J. D. Kurk, F. Walter, X. Fan, L. Jiang, S. Jester, H. W. Rix, D. A. Riechers

Research output: Contribution to journalArticlepeer-review

37 Scopus citations


We present sensitive near-infrared (NIR) VLT ISAAC spectroscopic observations of the z = 6.08 quasar SDSS J030331.40-001912.9. This quasi-stellar object (QSO) is more than a magnitude fainter than other QSOs at z ∼ 6 for which NIR spectroscopy has been obtained to date and is therefore presumably more representative of the QSO population at the end of cosmic reionization. Combining rest-frame UV continuum luminosity with the width measurements of the Mg II and C IV lines, we derive a black hole mass of 2+1.0 -0.5 × 108 M , the lowest mass observed for z ∼ 6 QSOs to date, and derive an Eddington ratio of 1.6 +0.4 -0.6, among the highest value derived for QSOs at any redshift. The Spitzer 24 μm nondetection of this QSO does not leave space for a significant hot dust component in its optical/NIR spectral energy distribution, in common with one other faint QSO at z = 6, but in contrast to more than 20 more z = 6 QSOs and all known lower redshift QSOs with sufficiently deep multiwavelength photometry. We conclude that we have found evidence for differences in the intrinsic properties of at least one z ∼ 6 QSO as compared to the lower redshift population.

Original languageEnglish (US)
Pages (from-to)833-837
Number of pages5
JournalAstrophysical Journal
Issue number2
StatePublished - 2009


  • Early universe
  • Galaxies: high-redshift
  • Quasars: emission lines
  • Quasars: individual

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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