摘要：22 GHz H2O megamaser disks, which trace a thin sub-pc scale molecular disk in Keplerian rotation movement around central SMBHs, provide us with a unique dynamic tool for measuring the geometric distance and enclosed mass to/within such systems. The Megamaser Cosmology Project (MCP) aims to constrain the Hubble Constant to better than 3% uncertainty with such disk maser systems. In the first part of my talk, I will give an update on the recent progress of MCP, as we have finished geometric distance measurements to 4 megamaser disk systems and they together yield H0 of 67.6 ± 4.0 km/s/Mpc. In addition, we also recently finished BH mass measurement in 5 new disk maser systems. Combined with velocity dispersion measurements, we confirmed that the megamaser disk hosting galaxies do not follow the empirical M-σ relationship defined by elliptical galaxies. Beyond that, I will also introduce several on-going/future projects that may shed light on maser pumping mechanism, AGN fueling and AGN outflows by studying such maser disk systems.
