Constraints on OH Megamaser Excitation from a Survey of OH Satellite
  Lines
  We report the results of a full-Stokes survey of all four 18 cm OH lines in
77 OH megamasers (OHMs) using the Arecibo Observatory. This is the first survey
of OHMs that included observations of the OH satellite lines; only 4 of the 77
OHMs have existing satellite line observations in the literature. In 5 sources,
satellite line emission is detected, with 3 of the 5 sources re-detections of
previously published sources. The 2 sources with new detections of satellite
line emission are IRAS F10173+0829, which was detected at 1720 MHz, and IRAS
F15107+0724, for which both the 1612 MHz and 1720 MHz lines were detected. In
IRAS F15107+0724, the satellite lines are partially conjugate, as 1720 MHz
absorption and 1612 MHz emission have the same structure at some velocities
within the source, along with additional broader 1612 MHz emission. This is the
first observed example of conjugate satellite lines in an OHM. In the remaining
sources, no satellite line emission is observed. The detections and upper
limits are generally consistent with models of OHM emission in which all of the
18 cm OH lines have the same excitation temperature. There is no evidence for a
significant population of strong satellite line emitters among OHMs.
