A 95 GHz Class I Methanol Maser Survey Toward A Sample of GLIMPSE Point
  Sources Associated with BGPS Clumps
  We report a survey with the Purple Mountain Observatory (PMO) 13.7-m radio
telescope for class I methanol masers from the 95 GHz (8_0 - 7_1 A^+)
transition. The 214 target sources were selected by combining information from
both the Spitzer GLIMPSE and 1.1 mm BGPS survey catalogs. The observed sources
satisfy both the GLIMPSE mid-IR criteria of [3.6]-[4.5]>1.3, [3.6]-[5.8]>2.5,
[3.6]-[8.0]>2.5 and 8.0 um magnitude less than 10, and also have an associated
1.1 mm BGPS source. Class I methanol maser emission was detected in 63 sources,
corresponding to a detection rate of 29% for this survey. For the majority of
detections (43), this is the first identification of a class I methanol maser
associated with these sources. We show that the intensity of the class I
methanol maser emission is not closely related to mid-IR intensity or the
colors of the GLIMPSE point sources, however, it is closely correlated with
properties (mass and beam-averaged column density) of the BGPS sources.
Comparison of measures of star formation activity for the BGPS sources with and
without class I methanol masers indicate that the sources with class I methanol
masers usually have higher column density and larger flux density than those
without them. Our results predict that the criteria
log(S_{int})<-38.0+1.72log(N_{H_{2}}^{beam}) and log(N_{H_{2}}^{beam})>22.1,
which utilizes both the integrated flux density (S_{int}) and beam-averaged
column density (N_{H_{2}}^{beam}) of the BGPS sources, are very efficient for
selecting sources likely to have an associated class I methanol maser. Our
expectation is that searches using these criteria will detect 90% of the
predicted number of class I methanol masers from the full BGPS catalog (~
1000), and do so with a high detection efficiency (~75%).
