  Hot, Dust-Obscured Galaxies, or "Hot DOGs", are a rare, dusty, hyperluminous
galaxy population discovered by the WISE mission. Predominantly at redshifts
2-3, they include the most luminous known galaxies in the universe. Their high
luminosities likely come from accretion onto highly obscured super massive
black holes (SMBHs). We have conducted a pilot survey to measure the SMBH
masses of five z~2 Hot DOGs via broad H_alpha emission lines, using
Keck/MOSFIRE and Gemini/FLAMINGOS-2. We detect broad H_alpha emission in all
five Hot DOGs. We find substantial corresponding SMBH masses for these Hot DOGs
(~ 10^{9} M_sun), and their derived Eddington ratios are close to unity. These
z~2 Hot DOGs are the most luminous AGNs at given BH masses, suggesting they are
accreting at the maximum rates for their BHs. A similar property is found for
known z~6 quasars. Our results are consistent with scenarios in which Hot DOGs
represent a transitional, high-accretion phase between obscured and unobscured
quasars. Hot DOGs may mark a special evolutionary stage before the red quasar
and optical quasar phases, and they may be present at other cosmic epochs.
