WISDOM project - VII. Molecular gas measurement of the supermassive black hole mass in the elliptical galaxy NGC 7052

Supermassive black hole (SMBH) masses can be measured by resolving the dynamical influences of the SMBHs on tracers of the central potentials. Modern long-baseline interferometers have enabled the use of molecular gas as such a tracer. We present here Atacama Large Millimeter/submillimeter Array observations of the elliptical galaxy NGC 7052 at 0′′.11 (37 pc) resolution in the 12CO(2-1) line and 1.3 mm continuum emission. This resolution is sufficient to resolve the region in which the potential is dominated by the SMBH. We forward model these observations, using a multi-Gaussian expansion of a Hubble Space Telescope F814W image and a spatially-constant mass-to-light ratio to model the stellar mass distribution. We infer a SMBH mass of 2.5 ± 0.3 × 109 M⊙ and a stellar I-band mass-to-light ratio of 4.6 ± 0.2 M⊙/L⊙, I (3σ confidence intervals). This SMBH mass is significantly larger than that derived using ionised gas kinematics, which however appear significantly more kinematically disturbed than the molecular gas. We also show that a central molecular gas deficit is likely to be the result of tidal disruption of molecular gas clouds due to the strong gradient in the central gravitational potential.