Limits on Vibrationally Excited HCN Emission in Four HCN-enhanced GOALS Galaxies

Vibrationally excited HCN emission can be used to identify luminous, optically obscured active galactic nucleus. We report Band 7 ALMA observations of four HCN-enhanced GOALS galaxies and derive upper limits to their vibrationally excited HCN emission. These upper limits and the lack of self-absorbed HCO+ line profiles imply that luminous, optically obscured energy sources are not present in this sample of systems.