Obscured Active Galactic Nuclei triggered in compact star-forming
  galaxies
  We present a structural study of 182 obscured Active Galactic Nuclei (AGNs)
at z<=1.5, selected in the COSMOS field from their extreme infrared to X-ray
luminosity ratio and their negligible emission at optical wavelengths. We fit
optical to far-infrared spectral energy distributions and analyze deep HST
imaging to derive the physical and morphological properties of their host
galaxies. We find that such galaxies are more compact than normal star-forming
sources at similar redshift and stellar mass, and we show that it is not an
observational bias related to the emission of the AGN. Based on the
distribution of their UVJ colors, we also argue that this increased compactness
is not due to the additional contribution of a passive bulge. We thus postulate
that a vast majority of obscured AGNs reside in galaxies undergoing dynamical
compaction, similar to processes recently invoked to explain the formation of
compact star-forming sources at high redshift.
