A spectroscopic survey of wise-selected obscured quasars with the southern african large telescope

Kevin N. Hainline, Ryan C. Hickox, Christopher M. Carroll, Adam D. Myers, Michael A. Dipompeo, Laura Trouille

Research output: Contribution to journalArticlepeer-review

27 Scopus citations

Abstract

We present the results of an optical spectroscopic survey of a sample of 40 candidate obscured quasars identified on the basis of their mid-infrared emission detected by the Wide-Field Infrared Survey Explorer (WISE). Optical spectra for this survey were obtained using the Robert Stobie Spectrograph on the Southern African Large Telescope. Our sample was selected with WISE colors characteristic of active galactic nuclei (AGNs), as well as red optical to mid-IR colors indicating that the optical/UV AGN continuum is obscured by dust. We obtain secure redshifts for the majority of the objects that comprise our sample (35/40), and find that sources that are bright in the WISE W4 (22 μm) band are typically at moderate redshift (〈z〉 = 0.35) while sources fainter in W4 are at higher redshifts (〈z〉 = 0.73). The majority of the sources have narrow emission lines with optical colors and emission line ratios of our WISE-selected sources that are consistent with the locus of AGN on the rest-frame g-z color versus [Ne III] λ3869/[O II] λλ3726+3729 line ratio diagnostic diagram. We also use empirical AGN and galaxy templates to model the spectral energy distributions (SEDs) for the objects in our sample, and find that while there is significant variation in the observed SEDs for these objects, the majority require a strong AGN component. Finally, we use the results from our analysis of the optical spectra and the SEDs to compare our selection criteria to alternate criteria presented in the literature. These results verify the efficacy of selecting luminous obscured AGNs based on their WISE colors.

Original languageEnglish (US)
Article number124
JournalAstrophysical Journal
Volume795
Issue number2
DOIs
StatePublished - Nov 10 2014
Externally publishedYes

Keywords

  • galaxies: active
  • galaxies: nuclei

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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