VLA Survey of Dense Gas in Extended Green Objects: Prevalence of 25 GHz
  Methanol Masers
  We present $\sim1-4"$ resolution Very Large Array (VLA) observations of four
CH$_3$OH $J_2-J_1$-$E$ 25~GHz transitions ($J$=3, 5, 8, 10) along with 1.3~cm
continuum toward 20 regions of active massive star formation containing
Extended Green Objects (EGOs), 14 of which we have previously studied with the
VLA in the Class~I 44~GHz and Class~II 6.7~GHz maser lines (Cyganowski et al.
2009). Sixteen regions are detected in at least one 25~GHz line ($J$=5), with
13 of 16 exhibiting maser emission. In total, we report 34 new sites of
CH$_3$OH maser emission and ten new sites of thermal CH$_3$OH emission,
significantly increasing the number of 25~GHz Class I CH$_3$OH masers observed
at high angular resolution. We identify probable or likely maser counterparts
at 44~GHz for all 15 of the 25~GHz masers for which we have complementary data,
providing further evidence that these masers trace similar physical conditions
despite uncorrelated flux densities. The sites of thermal and maser emission of
CH$_3$OH are both predominantly associated with the 4.5 $\mu$m emission from
the EGO, and the presence of thermal CH$_3$OH emission is accompanied by 1.3~cm
continuum emission in 9 out of 10 cases. Of the 19 regions that exhibit 1.3~cm
continuum emission, it is associated with the EGO in 16 cases (out of a total
of 20 sites), 13 of which are new detections at 1.3~cm. Twelve of the 1.3~cm
continuum sources are associated with 6.7~GHz maser emission and likely trace
deeply-embedded massive protostars.
