A classic type 2 QSO

Colin Norman, Guenther Hasinger, Riccardo Giacconi, Roberto Gilli, Lisa Kewley, Mario Nonino, Piero Rosati, Gyula Szokoly, Paolo Tozzi, Junxian Wang, Wei Zheng, Andrew Zirm, Jacqueline Bergeron, Roberto Gilmozzi, Norman Grogin, Anton Koekemoer, Ethan Schreier

Research output: Contribution to journalArticle

184 Citations (Scopus)


In the Chandra Deep Field-South 1 Ms exposure, we have found, at redshift 3.700 ± 0.005, the most distant type 2 active galactic nucleus ever detected. It is the source with the hardest X-ray spectrum with redshift z > 3. The optical spectrum has no detected continuum emission to a 3 σ detection limit of ∼3 × 10-19 ergs s-1 cm -2 Å-1 and shows narrow lines of Lyα, C IV, N V, He II, O VI, [O III], and C III]. Their FWHM line widths have a range of ∼700-2300 km s-1 with an average of approximately ∼1500 km s-1. The emitting gas is metal-rich (Z circled dash 2.5-3 Z ). In the X-ray spectrum of 130 counts in the 0.5-7 keV band, there is evidence for intrinsic absorption with NH ≳ 10 24 cm-2. An iron Kα line with rest-frame energy and equivalent width of ∼6.4 keV and ∼1 keV, respectively, in agreement with the obscuration scenario, is detected at a 2 σ level. If confirmed by our forthcoming XMM-Newton observations, this would be the highest redshift detection of Fe Kα. Depending on the assumed cosmology and the X-ray transfer model, the 2-10 keV rest frame luminosity corrected for absorption is ∼1045 ± 0.5 ergs cm-2 s-1, which makes our source a classic example of the long-sought type 2 QSO. From standard population synthesis models, these sources are expected to account for a relevant fraction of the black hole-powered QSO distribution at high redshift.

Original languageEnglish
Pages (from-to)218-225
Number of pages8
JournalAstrophysical Journal
Issue number1 I
Publication statusPublished - May 20 2002


  • Quasars: emission lines
  • Quasars: individual (CXOCDFS J033229.9-275106)
  • X-rays: galaxies

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Fingerprint Dive into the research topics of 'A classic type 2 QSO'. Together they form a unique fingerprint.

  • Cite this

    Norman, C., Hasinger, G., Giacconi, R., Gilli, R., Kewley, L., Nonino, M., Rosati, P., Szokoly, G., Tozzi, P., Wang, J., Zheng, W., Zirm, A., Bergeron, J., Gilmozzi, R., Grogin, N., Koekemoer, A., & Schreier, E. (2002). A classic type 2 QSO. Astrophysical Journal, 571(1 I), 218-225. https://doi.org/10.1086/339855