Observations of hydroxyl in early-type galaxies
  We used Arecibo Observatory and the Green Bank Telescope to observe OH in
twelve early-type galaxies with known reservoirs of dense gas. We present three
new detections of OH in absorption in the 1667 MHz line. One objective of our
survey was to find evidence of molecular outflows, but our sensitivity, and the
strength of the OH absorption, were insufficient to detect outflows. The
detected sources have infrared luminosities and dust temperatures among the
lowest of any galaxy detected in OH absorption. The ratio $L_{\rm HCN} / L_{\rm
CO}$, a measure of the dense gas fraction in galaxies, is a powerful selector
of OH megamasers for galaxies with high infrared luminosity. In early-type
galaxies, which have much lower infrared luminosities, $L_{\rm HCN} / L_{\rm
CO}$ is also a promising tool for discovering OH, but in absorption rather than
in maser emission. In addition to dense molecular gas, a radio continuum source
and a favorable line-of-sight to the observer are likely key factors in
detecting OH absorbers.
