• DOI:10.1086/378610
• Corpus ID: 13477694

Candidate Type II Quasars from the Sloan Digital Sky Survey. I. Selection and Optical Properties of a Sample at 0.3 < Z < 0.83

@article{Zakamska2003CandidateTI,
  title={Candidate Type II Quasars from the Sloan Digital Sky Survey. I. Selection and Optical Properties of a Sample at 0.3 < Z < 0.83},
  author={Nadia L. Zakamska and Michael A. Strauss and Julian H. Krolik and Matthew J. Collinge and Patrick B. Hall and Lei Hao and Timothy M. Heckman and Željko Ivezi{\'c} and Gordon T. Richards and David J. Schlegel and Donald P. Schneider and Iskra V. Strateva and Daniel E. vanden Berk and Scott F. Anderson and Jonathan Brinkmann},
  journal={The Astronomical Journal},
  year={2003},
  volume={126},
  pages={2125 - 2144}
}

• N. Zakamska, M. Strauss, +12 authors J. Brinkmann
• Published 20 September 2003
• Physics
• The Astronomical Journal

Type II quasars are the long-sought luminous analogs of type 2 (narrow emission line) Seyfert galaxies, suggested by unification models of active galactic nuclei (AGNs) and postulated to account for an appreciable fraction of the cosmic hard X-ray background. We present a sample of 291 type II AGNs at redshifts 0.3 < Z < 0.83 from the spectroscopic data of the Sloan Digital Sky Survey. These objects have narrow (FWHM < 2000 km s-1), high equivalent width emission lines with high-ionization line ratios. We describe the selection procedure and discuss the optical properties of the sample. About 50% of the objects have [O III] λ5008 line luminosities in the range 3 × 108–1010 L⊙, comparable to those of luminous (-27 < MB < -23) quasars; this, along with other evidence, suggests that the objects in the luminous subsample are type II quasars.