- Broida 3302
Fred Lo (Caltech)
The Mega-maser Cosmology Project (MCP) aims to determine the Hubble Constant, Ho, to ~3 percent accuracy by measuring the angular diameter distance to "mega-maser galaxies" that harbor circum-nuclear Keplerian disks exhibiting powerful water maser emission. Under the MCP, mega-maser search using the GBT and mapping using the VLBA and GBT have now identified 10 mega-maser galaxies with distances ranging from 30 Mpc to 140 Mpc, well in the Hubble flow. A 10% angular diameter distance determination to NGC6264 at 150 Mpc has been demonstrated. A by-product of the MCP is precise mass determination of the supermassive black-holes (BH) in the mega-maser galaxies. The mega-maser BH mass results appear to be inconsistent with the putative M-sigma relationship between black holes and galactic bulges. The status of the MCP will be described. The current status and recent science of ALMA and other NRAO facilities will also be presented.