Recovering Intrinsic Molecular Disk Properties in ALMA Imaging of Massive Galaxies: Precision Measurements of CO Hole Radii

With its unparalleled sensitivity and angular resolution capabilities, the Atacama Large Millimeter/submillimeter Array has enabled detailed mapping of the CO emission arising from circumnuclear, dusty disks in many nearby early-type galaxies. At high physical resolutions, these disks typically show central holes in their CO emission-line distributions with characteristic radii of 10-30 pc from their supermassive black holes. The exact mechanism producing the central CO deficits are unknown. We have developed a gas-dynamical modeling code to recover the intrinsic radii of the central CO holes in galactic core circumnuclear disks from ALMA data cubes. We demonstrate the viability of this method by application to ALMA imaging of the elliptical type galaxies NGC 0383, NGC 0524, NGC 4429, NGC 3258, and NGC 6861 to measure the intrinsic CO hole radius of each galaxy. Our findings demonstrate the efficacy of our new method for gauging the intrinsic hole radius from ALMA data, which can be used to study active galactic nucleus feeding cycles, the longevity of these circumnuclear disks, and potential correlations with the supermassive black hole mass or other galactic properties.