High-excitation CO in a quasar host galaxy at z = 6.42

F. Bertoldi, P. Cox, R. Neri, C. L. Carilli, F. Walter, A. Omont, A. Beelen, C. Henkel, X. Fan, Michael A. Strauss, K. M. Menten

Research output: Contribution to journalLetterpeer-review

193 Scopus citations


We report the detection of high excitation CO emission from the most distant quasar currently known, SDSS J114816.64+525150.3 (hereafter J1148+5251), at a redshift z = 6.419. The CO (J = 6 → 5) and (J = 7 → 6) lines were detected using the IRAM Plateau de Bure interferometer, showing a width of ≈280 km s-1. An upper flux limit for the CO (J = 1 → 0) line was obtained from observations with the Effelsberg 100-meter telescope. Assuming no gravitational magnification, we estimate a molecular gas mass of ≈2 × 1010 M. Using the CO (3 → 2) observations by Walter et al. (2003), a comparison of the line flux ratios with predictions from a large velocity gradient model suggests that the gas is likely of high excitation, at densities ∼104.5 cm-3 and a temperature ∼100 K. Since in this case the CO lines appear to have moderate optical depths, the gas must be extended over a few kpc. The gas mass detected in J1148+5251 can fuel star formation at the rate implied by the far-infrared luminosity for less than 10 million years, a time comparable to the dynamical time scale of the region. The gas must therefore be replenished quickly, and metal and dust enrichment must occur fast. The strong dust emission and the massive, dense gas reservoir at z ∼ 6.4 provide further evidence that vigorous star formation is co-eval with the rapid growth of massive black holes at these early epochs of the Universe.

Original languageEnglish (US)
Pages (from-to)L47-L50
JournalAstronomy and Astrophysics
Issue number3
StatePublished - Oct 2003

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • Cosmology: observations
  • Galaxies: formation
  • Galaxies: high-redshift
  • Galaxies: starburst
  • Quasars: emission lines
  • Quasars: individual: SDSS J1148+5251


Dive into the research topics of 'High-excitation CO in a quasar host galaxy at z = 6.42'. Together they form a unique fingerprint.

Cite this