A Search for Extragalactic Methanol Masers

A sensitive search for 6.7–GHz methanol maser emission has been made towards 10 galaxies that have yielded detectable microwave molecular–line transitions. These include several which show OH megamaser or superluminous H 2 O maser emission. Within the Galaxy, CH 3 OH and OH masers often occur in the same star formation regions and, in most cases, the CH 3 OH masers have a greater peak flux density than their OH counterparts. Thus we might expect CH 3 OH masers to be associated with extragalactic OH maser sources. We failed to detect any emission or absorption above our 60–mJy detection limit. We conclude that if the physical conditions exist to produce CH 3 OH megamaser emission, they are incompatible with the conditions which produce OH megamaser emission.