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

2003/09/20 by Nadia L. Zakamska, Michael A. Strauss, Julian H. Krolik +23 · 2 citations
Physics and Astronomy · #Astrophysical Phenomena and Observations #Galaxies: Formation, Evolution, Phenomena #Gamma-ray bursts and supernovae #astro-ph

paper · pdf · doi:10.1086/378610

published as Astron.J.126:2125,2003 · Accepted to AJ (November issue), 46 pages including 2 tables and 15 figures, the full version of Table 1 is available at http://www.astro.princeton.edu/~nadia/qso2.html

arxiv created 2003/09/20 · openalex publication_date 2003/11/01 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/31

Abstract

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 × 10 8 –10 10 L ⊙ , comparable to those of luminous (-27 < M B < -23) quasars; this, along with other evidence, suggests that the objects in the luminous subsample are type II quasars.

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Cited by

• The FIRST‐2MASS Red Quasar Survey
• Quasar [wikipedia]