Dedicated searches generally find a decreasing fraction of obscured Active Galactic Nuclei ( AGN ) with increasing AGN luminosity .
This has often been interpreted as evidence for a decrease of the covering factor of the AGN torus with increasing luminosity , the so-called receding torus models .
Using a complete flux-limited X-ray selected sample of 199 AGN , from the Bright Ultra-hard XMM-Newton Survey , we determine the intrinsic fraction of optical type-2 AGN at 0.05 \leq z \leq 1 as a function of rest-frame 2-10 keV X-ray luminosity from { 10 ^ { 42 } } to { 10 ^ { 45 } erg s ^ { -1 } } .
We use the distributions of covering factors of AGN tori derived from CLUMPY torus models .
Since these distributions combined over the total AGN population need to match the intrinsic type-2 AGN fraction , we reveal a population of X-ray undetected objects with high-covering factor tori , which are increasingly numerous at higher AGN luminosities .
When these ” missing ” objects are included , we find that Compton-thick AGN account at most for 37 _ { -10 } ^ { +9 } % of the total population .
The intrinsic type-2 AGN fraction is 58 \pm 4 % and has a weak , non-significant ( less than 2 \sigma ) luminosity dependence .
This contradicts the results generally reported by AGN surveys , and the expectations from receding torus models .
Our findings imply that the majority of luminous rapidly-accreting supermassive black holes at z \leq 1 reside in highly-obscured nuclear environments but most of them are so deeply embedded that they have so far escaped detection in X-rays in < 10 keV wide-area surveys .