Presentation #105.12 in the session Molecular Clouds and the ISM — iPoster Session.
The Atacama Large Millimeter/submillimeter Array (ALMA) has observed nearby giant elliptical galaxy M87 many times. A few of these projects were specifically designed to measure and resolve low-J CO transitions from circumnuclear molecular gas near its supermassive black hole (BH). However, there are currently no published emission-line results from ALMA imaging of the M87 nucleus. Here, we describe a molecular line search using data from 11 projects in the ALMA archive. After correcting a few manual calibration errors and comparing to atmospheric transmission models, we identified faint CO absorption features against the bright M87 nucleus that correspond to an H2 column density ranging between 0.2–3.5×1022 cm-2. In addition to these absorption lines, we also detect very broad CO emission-line features that are Doppler-shifted by ~1000–1500 km s-1. Assuming disk-like rotation, the CO emission may trace the gas kinematics in the central few parsecs. We also determine ALMA configuration and sensitivity requirements to map out the potential CO disk for future proposals.