Science Highlights - Measuring the Mass of the Supermassive Black Hole in NGC 3258 with ALMA

High-resolution ALMA observations hold the promise of measuring accurate dynamical masses for a wide variety of astronomical objects. In a 2019 paper, Dr. Boizelle and his collaborators make use of 0.1” resolution observations of CO(2-1) emission from the central 150 pc-radius molecular disk of NGC 3258 to estimate the galaxy’s central supermassive black hole mass. The position-velocity diagram (see the Figure) of the CO(2-1) emission shows a quasi-Keplerian profile. The velocity rises from 280 km/s to > 400 km/s near the center of the disk - this rise is due to gas under the direct gravitational influence of the supermassive black hole. The velocity profile is well-fitted by a mildly warped disk, leading to a derived supermassive black hole mass of 2x10⁹ M_sun for this giant elliptical galaxy.