We construct a sample of X-ray bright optically faint active galactic nuclei by combining Subaru Hyper Suprime-Cam , XMM-Newton , and infrared source catalogs .
53 X-ray sources satisfying i band magnitude fainter than 23.5 mag and X-ray counts with EPIC-PN detector larger than 70 are selected from 9.1 deg ^ { 2 } , and their spectral energy distributions ( SEDs ) and X-ray spectra are analyzed.44 objects with an X-ray to i -band flux ratio F _ { X } / F _ { i } > 10 are classified as extreme X-ray-to-optical flux sources .
SEDs of 48 among 53 are represented by templates of type 2 AGNs or starforming galaxies and show signature of stellar emission from host galaxies in the optical in the source rest frame .
Infrared/optical SEDs indicate significant contribution of emission from dust to infrared fluxes and that the central AGN is dust obscured .
Photometric redshifts determined from the SEDs are in the range of 0.6–2.5 .
X-ray spectra are fitted by an absorbed power law model , and the intrinsic absorption column densities are modest ( best-fit \log N _ { H } = 20.5 - 23.5 cm ^ { -2 } in most cases ) .
The absorption corrected X-ray luminosities are in the range of 6 \times 10 ^ { 42 } -2 \times 10 ^ { 45 } erg s ^ { -1 } .
20 objects are classified as type 2 quasars based on X-ray luminsosity and N _ { H } .
The optical faintness is explained by a combination of redshifts ( mostly z > 1.0 ) , strong dust extinction , and in part a large ratio of dust/gas .