LBA observations for project V598 semester 2020OCTS

Since the early 1990's we have known that water megamaser emission is a powerful probe for the investigation of supermassive black holes in AGN (Nakai et al., 1993; Miyoshi et al., 1995; Moran et al., 1995). These extragalactic water masers are observed to reside within (or be located within) a circumnuclear disk of molecular gas within 1 pc of the central black hole of their host galaxies. The prototypical example of nuclear water masers is seen towards NGC~4258, where the masers trace a thin circumnuclear Keplerian disk of radius 0.13 pc (Miyoshi et al., 1995). \r\n\r\n22-GHz water masers have been detected toward the nucleus of NGC 4945, however, currently these masers are poorly understood with only one published map of the masers to date (Greenhill et al., 1997). Our proposed observations will investigate the seemingly complex nature of the circumnuclear disk in NGC 4945 and address uncertainty regarding the structure of the host AGN. They will improve on existing data by achieving higher angular resolution, increasing bandwidth in order to detect the host AGN continuum emission, phase referencing for determination of absolute positions of the masers and provide a modern epoch of observation for comparison with recent maser and molecular line studies from ATCA and ALMA toward NGC 4945.