Searching for Obscured Quasars with WISE and the Southern African Large Telescope

We present the results of an optical spectroscopic survey of a sample of 43 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 (RSS) on the Southern African Large Telescope (SALT). Our target objects are selected to have red WISE colors characteristic of AGN, 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 (37/43), and find that sources that are bright in the WISE 22μm band are typically at moderate redshift (0.2-0.5) while 22μm fainter sources are at higher redshifts. 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 color-excitation diagram between rest-frame g - z color and [NeIII]λ3869 / [OII]λλ3726+3729 line ratio. These results verify the efficiency of WISE color criteria in selecting luminous obscured AGN.