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Candidate Type II Quasars from the Sloan Digital Sky Survey. I. Selection and Optical Properties of a Sample at 0.3 <Z < 0.83
Nadia L. Zakamska,Michael A. Strauss,Julian H. Krolik,Matthew J. Collinge,Patrick B. Hall,Lei Hao,Timothy M. Heckman,Željko Ivezić,Gordon T. Richards,David J. Schlegel
© 2003. The American Astronomical Society. All rights reserved. Printed in U.S.A.
The Astronomical Journal,Volume 126,Number 5Citation Nadia L. Zakamskaet al 2003AJ126 2125DOI 10.1086/378610
Nadia L. Zakamska
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Princeton University Observatory, Peyton Hall, Ivy Lane, Princeton, NJ 08544
Michael A. Strauss
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Princeton University Observatory, Peyton Hall, Ivy Lane, Princeton, NJ 08544
Julian H. Krolik
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Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218-2686
Matthew J. Collinge
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Princeton University Observatory, Peyton Hall, Ivy Lane, Princeton, NJ 08544
Patrick B. Hall
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Princeton University Observatory, Peyton Hall, Ivy Lane, Princeton, NJ 08544
Lei Hao
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Princeton University Observatory, Peyton Hall, Ivy Lane, Princeton, NJ 08544
Timothy M. Heckman
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Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218-2686
Željko Ivezić
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Princeton University Observatory, Peyton Hall, Ivy Lane, Princeton, NJ 08544
Gordon T. Richards
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Princeton University Observatory, Peyton Hall, Ivy Lane, Princeton, NJ 08544
David J. Schlegel
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Princeton University Observatory, Peyton Hall, Ivy Lane, Princeton, NJ 08544
Donald P. Schneider
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Department of Astronomy and Astrophysics, 525 Davey Laboratory, Pennsylvania State University, University Park, PA 16802
Iskra Strateva
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Princeton University Observatory, Peyton Hall, Ivy Lane, Princeton, NJ 08544
Daniel E. Vanden Berk
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Department of Physics and Astronomy, University of Pittsburgh, 3941 O’Hara Street, Pittsburgh, PA 15260
Scott F. Anderson
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Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195
Jon Brinkmann
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Apache Point Observatory, P.O. Box 59, Sunspot, NM 88349
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- Received2003 June 23
- Accepted2003 July 22
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 × 108–1010L⊙, 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.