Simultaneous Survey of Water and Class I Methanol Masers toward Red MSX
  Sources
  We report simultaneous single-dish surveys of 22 GHz H2O and 44 and 95 GHz
class I CH3OH masers toward 299 Red MSX Sources in the protostellar stage. The
detection rates are 45% at 22 GHz, 28% at 44 GHz, and 23% at 95 GHz. There are
15, 53, and 51 new discoveries at 22, 44, and 95 GHz, respectively. We detect
high-velocity (>30 km/s) features in 27 H2O maser sources. The 95 GHz maser
emission is detected only in 44 GHz maser sources. The two transitions show
strong correlations in the peak velocity, peak flux density, and isotropic
maser luminosity, indicating that they are likely generated in the same sites
by the same mechanisms. The 44 GHz masers have much narrower distributions than
22 GHz masers in the relative peak velocity and velocity range, while 6.7 GHz
class II CH3OH masers have distributions intermediate between the two. The
maser luminosity significantly correlates with the parental clump mass, while
it correlates well with the bolometric luminosity of the central protostar only
when data of the low-mass regime from the literature are added. Comparison with
the results of previous maser surveys toward massive star-forming regions
suggests that the detection rates of 22 and 44 GHz masers tend to increase as
the central objects evolve. This is contrary to the trends found in low- and
intermediate-mass star-forming regions. Thus the occurrence of both masers
might depend on the surrounding environments as well as on the evolution of the
central object.
