Near-infrared spectra and intrinsic luminosities of candidate Type II quasars at 2 < z < 3.4

Jenny E. Greene, Rachael Alexandroff, Michael A. Strauss, Nadia L. Zakamska, Dustin Lang, Guilin Liu, Petchara Pattarakijwanich, Frederick Hamann, Nicholas P. Ross, Adam D. Myers, W. Niel Brandt, Donald York, Donald P. Schneider

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Abstract

We present JHK near-infrared (NIR) spectroscopy of 25 candidate Type II quasars selected from the Sloan Digital Sky Survey (SDSS), using Triplespec on the Apache Point Observatory 3.5 m telescope, the Folded-port InfraRed Echellette at the Magellan/Baade 6.5 m telescope, and the Gemini Near-Infrared Spectrograph on Gemini. At redshifts of 2 < z < 3.4, our NIR spectra probe the rest-frame optical region of these targets, which were initially selected to have strong lines of C IV and Ly α, with FWHM < 2000 km s -1 from the SDSS pipeline. We use the [O III] λ5007 line shape as a model for the narrow-line region emission and find that Hα consistently requires a broad component with FWHMs ranging from 1000 to 7500 km s-1. Interestingly, the C IV lines also require broad bases, but with considerably narrower widths of 1000-4500 km s-1. Estimating the extinction using the Balmer decrement and also the relationship in lower-z quasars between rest equivalent width and luminosity in the [O III] line, we find typical AV values of 0-2 mag, which naturally explains the attenuated C IV lines relative to Hα. We propose that our targets are moderately obscured quasars. We also describe one unusual object with three distinct velocity peaks in its [O III] spectrum.

Original languageEnglish (US)
Article number91
JournalAstrophysical Journal
Volume788
Issue number1
DOIs
StatePublished - Jun 10 2014

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Keywords

  • quasars: emission lines
  • quasars: general
  • quasars: supermassive black holes

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    Greene, J. E., Alexandroff, R., Strauss, M. A., Zakamska, N. L., Lang, D., Liu, G., Pattarakijwanich, P., Hamann, F., Ross, N. P., Myers, A. D., Brandt, W. N., York, D., & Schneider, D. P. (2014). Near-infrared spectra and intrinsic luminosities of candidate Type II quasars at 2 < z < 3.4. Astrophysical Journal, 788(1), [91]. https://doi.org/10.1088/0004-637X/788/1/91