The most heavily-obscured, luminous quasars might represent a specific phase of the evolution of the actively accreting supermassive black holes and their host galaxies, possibly related to mergers. We investigated a sample of the most luminous quasars at z ≈ 1 − 3 in the GOODS fields, selected in the mid-infrared band through detailed spectral energy distribution (SED) decomposition. The vast majority of these quasars (~80%) are obscured in the X-ray band and ~30% of them to such an extent, that they are undetected in some of the deepest (2 and 4 Ms) Chandra X-ray data. Although no clear relation is found between the star-formation rate of the host galaxies and the X-ray obscuration, we find a higher incidence of heavily-obscured quasars in disturbed/merging galaxies compared to the unobscured ones, thus possibly representing an earlier stage of evolution, after which the system is relaxing and becoming unobscured.

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Published in Frontiers in Astronomy and Space Sciences, v. 4, article 67, p. 1-5.

Copyright © 2018 Del Moro, Alexander, Bauer, Daddi, Kocevski, Stanley and McIntosh.

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This research was supported by the UK Science and Technology Facilities Council (STFC, ST/L00075X/1); CONICYT-Chile (Basal-CATA PFB-06/2007, “EMBIGGEN” Anillo ACT1101, FONDECYT Regular 1141218); the Ministry of Economy, Development, and Tourism's Millennium Science Initiative through grant IC120009, awarded to The Millennium Institute of Astrophysics (MAS).