High-z X-ray Obscured Quasars in Galaxies with Extreme Mid-IR/Optical Colors

Abstract

Extreme Optical/Mid‐IR color cuts have been used to uncover a population of dust‐enshrouded, mid‐IR luminous galaxies at high redshifts. Several lines of evidence point towards the presence of an heavily absorbed, possibly Compton‐thick quasar at the heart of these systems. Nonetheless, the X‐ray spectral properties of these intriguing sources still remain largely unexplored. Here we present an X‐ray spectroscopic study of a large sample of 44 extreme dust‐obscured galaxies (EDOGs) with F_(24μm)/F_R > 2000 and F_(24μm) > 1.3 mJy selected from a 6 deg^2 region in the SWIRE fields. The application of our selection criteria to a wide area survey has been capable of unveiling a population of X‐ray luminous, absorbed z > 1 quasars which is mostly missed in the traditional optical/X‐ray surveys performed so far. Advances in the understanding of the X‐ray properties of these recently‐discovered sources by Simbol‐X observations will be also discussed.

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