Candidate type II quasars from the Sloan Digital Sky Survey.: I.: Selection and optical properties of a sample at 0.3 < Z < 0.83

被引：315
作者：
Zakamska, NL
Strauss, MA
Krolik, JH
Collinge, MJ
Hall, PB
Hao, L
Heckman, TM
Ivezic, Z
Richards, GT
Schlegel, DJ
Schneider, DP
Strateva, I
Vanden Berk, DE
Anderson, SF
Brinkmann, J
机构：
[1] Princeton Univ Observ, Princeton, NJ 08544 USA
[2] Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA
[3] Penn State Univ, Dept Astron & Astrophys, Davy Lab 525, University Pk, PA 16802 USA
[4] Univ Pittsburgh, Dept Phys & Astron, Pittsburgh, PA 15260 USA
[5] Univ Washington, Dept Astron, Seattle, WA 98195 USA
[6] Apache Point Observ, Sunspot, NM 88349 USA
来源：
ASTRONOMICAL JOURNAL | 2003年 / 126卷 / 05期
关键词：
galaxies : active; quasars : emission lines; quasars : general; surveys;
D O I：
10.1086/378610
中图分类号：
P1 [天文学];
学科分类号：
0704 ;
摘要：
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 3x10(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.
引用
收藏
页码：2125 / 2144
页数：20
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