At low redshifts , dust-obscured quasars often have strong yet narrow permitted lines in the rest-frame optical and ultraviolet , excited by the central active nucleus , earning the designation Type II quasars .
We present a sample of 145 candidate Type II quasars at redshifts between 2 and 4.3 , encompassing the epoch at which quasar activity peaked in the universe .
These objects , selected from the quasar sample of the Baryon Oscillation Spectroscopic Survey of the Sloan Digital Sky Survey III , are characterized by weak continuum in the rest-frame ultraviolet ( typical continuum magnitude of i \approx 22 ) and strong lines of C IV and Ly \alpha , with Full Width at Half Maximum less than 2000 km s ^ { -1 } .
The continuum magnitudes correspond to an absolute magnitude of -23 or brighter at redshift 3 , too bright to be due exclusively to the host galaxies of these objects .
Roughly one third of the objects are detected in the shorter-wavelength bands of the WISE survey ; the spectral energy distributions ( SEDs ) of these objects appear to be intermediate between classic Type I and Type II quasars seen at lower redshift .
Five objects are detected at rest frame 6µm by Spitzer , implying bolometric luminosities of several times 10 ^ { 46 } erg s ^ { -1 } .
We have obtained polarization measurements for two objects ; they are roughly 3 % polarized .
We suggest that these objects are luminous quasars , with modest dust extinction ( A _ { V } \sim 0.5 mag ) , whose ultraviolet continuum also includes a substantial scattering contribution .
Alternatively , the line of sight to the central engines of these objects may be obscured by optically thick material whose covering fraction is less than unity .