Detection of H2O and OH+ in z>3 Hot Dust-Obscured Galaxies
  In this paper we present the detection of H2O and OH+ emission in z>3 hot
dust-obscured galaxies (Hot DOGs). Using ALMA Band-6 observations of two Hot
DOGs, we have detected H2O(2_02-1_11) in W0149+2350, and H2O(3_12-3_03) and the
multiplet OH+(1_1-0_1) in W0410-0913. We find that both sources have luminous
H2O emission with line luminosities of L_H2O > 2.2x10^8 Lsol and L_H2O =
8.7x10^8 Lsol for W0149+2350 and W0410-0913, respectively. The H2O line
profiles are similar to those seen for the neighbouring CO(9-8) line, with
linewidths of FWHM ~ 800-1000 km/s. However, the H2O emission seems to be more
compact than the CO(9-8). OH+ is detected in emission for W0410-0913, with a
FWHM=1000km/s and a line luminosity of L_OH+ = 6.92x10^8 Lsol. The ratio of the
observed H2O line luminosity over the IR luminosity, for both Hot DOGs, is
consistent with previously observed star forming galaxies and AGN. The H2O/CO
line ratio of both Hot DOGs and the OH+/H2O line ratio of W0410-0913 are
comparable to those of luminous AGN in the literature. The bright
H2O(2_02-1_11), and H2O(3_12-3_03) emission lines are likely due to the
combined high star formation levels and luminous AGN in these sources. The
presence of OH+ in emission, and the agreement of the observed line ratios of
the Hot DOGs with luminous AGN in the literature, would suggest that the AGN
emission is dominating the radiative output of these galaxies. However,
followup multi-transition observations are needed to better constrain the
properties of these systems.
