Luminous and obscured quasars and their host galaxies
  The most heavily-obscured, luminous quasars might represent a specific phase
of the evolution of actively accreting supermassive black holes and their host
galaxies, possibly related to mergers. We investigated a sample of the most
luminous quasars at $z\approx 1-3$ 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.
