Identifying the Obscured Black-Hole Growth Phase of Distant Massive
  Galaxies
  It is well established that a dominant phase in the growth of massive
galaxies occurred at high redshift and was heavily obscured by gas and dust.
Many studies have explored the stellar growth of massive galaxies but few have
combined these constraints with the growth of the supermassive black hole
(SMBH; i.e., identified as AGN activity). In this brief contribution we
highlight our work aimed at identifying AGNs in z~2 luminous dust-obscured
galaxies. Using both sensitive X-ray and infrared (IR)-submillimeter (submm)
observations, we show that AGN activity is common in z~2 dust-obscured systems.
With a variety of techniques we have found that the majority of the AGN
activity is heavily obscured, and construct diagnostics based on X-ray-IR data
to identify some of the most heavily obscured AGNs in the Universe (i.e., AGNs
obscured by Compton-thick material; N_H>1.5x10^24 cm^-2). On the basis of these
techniques we show that SMBH growth was typically heavily obscured (N_H>10^23
cm^-2) at z~2, and find that the growth of the SMBH and spheroid was closely
connected, even in the most rapidly evolving systems.
