Recent X-ray surveys with Chandra and XMM- Newton have found several genuine Type II quasars , the long sought-after population of high-luminosity ( high-redshift ) Seyfert 2 galaxies , and a sizable number of Type II quasar candidates .
However , at present it is hard to know whether the on-going X-ray surveys are providing a reliable and nearly complete census of the Type II quasar population .
In order to address this open issue and shed light on the broad-band properties of Type II quasars , we used the sample of 291 high-ionization narrow emission-line AGN at z =0.3–0.83 selected from the Sloan Digital Sky Survey by Zakamska et al .
( 20 ) .
Using archival X-ray information , we were able to place constraints on the X-ray emission of 17 of these objects ( three X-ray detections and 14 upper limits ) .
Using the [ O iii ] \lambda 5007 line luminosities to predict the intrinsic X-ray power of the AGN , we found that at least 47 % of the objects in the observed sample provides evidence for the presence of X-ray absorption ( with N _ { H } \mathrel { \hbox { \hbox to 0.0 pt { \hbox { \lower 4.0 pt \hbox { $ \sim$ } } } \hbox { $ > $ } } } 10 ^ { 22 } cm ^ { -2 } ) , including the four highest luminosity sources with predicted unobscured luminosities of \approx 10 ^ { 45 } erg s ^ { -1 } .
For the only source with moderate-quality XMM- Newton spectral data , all of the pieces of the puzzle ( 2–10 keV luminosity of \approx 4 \times 10 ^ { 44 } erg s ^ { -1 } , N _ { H } \approx 1–3 \times 10 ^ { 22 } cm ^ { -2 } , and unobscured magnitude M _ { B } \approx - 26 ) assure that this is a genuine Type II quasar .