A More Efficient Search for H2O Megamaser Galaxies : The Power of the
  X-ray and Mid-infrared Photometry
  We present a new investigation of the dependence of H2O maser detection rates
and properties on the mid-IR AGN luminosity, L_AGN, and the obscuring column
density, N_H, based on mid-IR and hard X-ray photometry. Based on spectral
energy distribution fitting that allows for decomposition of the black hole
accretion and star-formation components in the mid-infrared, we show that the
megamaser (disk maser) detection rate increases sharply for galaxies with 12
micron AGN luminosity L^{AGN}_{12 micron} greater than 10^42 erg/s, from
~<3%(~<2%) to ~12%(~5%). By using the ratio of the observed X-ray to mid-IR AGN
luminosity as an indicator of N_H, we also find that the megamaser (disk maser)
detection rates are boosted to 15%(7%) and 20%(9%) for galaxies with N_H >=
10^23 cm^{-2} and N_H >= 10^{24} cm^{-2}, respectively. Combining these column
density cuts with a constraint for high L^{AGN}_{12 micron} (>=10^42 erg/s)
predicts further increases in the megamaser (disk maser) detection rates to
19%(8%) and 27%(14%), revealing unprecedented potential boosts of the megamaser
and disk maser detection rates by a factor of 7-15 relative to the current
rates, depending on the chosen sample selection criteria. A noteworthy aspect
of these new predictions is that the completeness rates are only compromised
mildly, with the rates remaining at the level of ~95%(~50%) for sources with
N_H >= 10^{23} cm^{-2} (N_H >= 10^24 cm^-2). Applying these selection methods
to the current X-ray AGN surveys predicts the detection of >~15 new megamaser
disks.
