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Title: An unobscured type II quasar candidate: SDSS J012032.19-005501.9

We report the finding of an unobscured type II active galactic nucleus (AGN) candidate, SDSS J012032.19-005501.9, at a relatively high redshift of 0.601, which shows a number of unusual properties. It varies significantly on timescales of years, typical of type I AGNs, and marginally on timescales of weeks. The color–magnitude relation and the structure function are also consistent with that of type I AGNs, which implies that its variability likely originates from the black hole accretion system. However, no broad emission line (BEL) is detected in the Sloan Digital Sky Survey spectrum, and the upper limit of the equivalent width of the Hβ BEL is much less than that of type I AGNs. These properties suggest that SDSS J012032.19-005501.9 may be an unobscured quasar without intrinsically broad emission lines, namely, an unobscured type II AGN or “true” type II AGN. Furthermore, its continuum luminosity is at least one order of magnitude fainter than the average value over the past century from the [O iii] emission line. This indicates that SDSS J012032.19-005501.9 may be switching off. Additional possible scenarios to explain this intriguing source are also discussed. Future deep observations at multiwavelengths are needed to reveal the nature of this peculiarmore » and intriguing AGN.« less
Authors:
; ;  [1] ; ;  [2] ;  [3] ;  [4]
  1. National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Beijing 100012 (China)
  2. Key Laboratory for Research in Galaxies and Cosmology, University of Sciences and Technology of China, Chinese Academy of Sciences, Hefei, Anhui 230026 (China)
  3. Department of Astronomy, Peking University, Beijing 100871 (China)
  4. Department of Physics and Astronomy, University of Nevada, Las Vegas, NV 89154 (United States)
Publication Date:
OSTI Identifier:
22342107
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astronomical Journal (New York, N.Y. Online); Journal Volume: 149; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BLACK HOLES; COLOR; EMISSION; GALAXIES; GALAXY NUCLEI; LUMINOSITY; QUASARS; RED SHIFT; SKY; SPECTRA; STRUCTURE FUNCTIONS