High-frequency water megamasers as precision probes of black holes, galaxies and cosmology: A case for a next-generation sub-mm/mm interferometer
High-frequency water megamasers serve as precise probes for black holes and cosmology. A next-generation sub-mm/mm interferometer, ALMA2040, is proposed to transform these studies into a population-level tool. This advancement will enable accurate measurements of black hole masses, geometric distances, and constraints on the Hubble Constant.