Water vapor masers have been detected in about 150 galaxies, most of them
in nearby, narrow-line AGNs. In about 20 percent of these galaxies, the
masers appear to originate from circumnuclear gas in AGN accretion disks
viewed edge-on. Spectacular VLBI observations of such megamasers show gas in
Keplerian rotation within a parsec of the dynamical center. In some cases,
we can use the masers to determine geometric distances to the host galaxies,
providing a valuable measurement of the Hubble constant independent of
standard candles. Measuring H_0 with high precision is key to constraining
models of dark energy. The VLBI observations also provide the most precise
masses of supermassive black holes in external galaxies. These measurements
provide a critical test of the black hole-bulge scaling relations that strongly
influence our understanding of galaxy evolution. The Megamaser Cosmology
Project (MCP) is an NRAO key project that aims to identify new masers in AGN
accretion disks and make the observations necessary to measure their distances
and black hole masses. In this talk I will discuss recent results and future
plans for the MCP.
No
October 21, 2011
11:00 am
Array Operations Center Auditorium
All NRAO employees are invited to attend via video, available in Charlottesville Room 230, Green Bank Room 137 and Tucson N525.
Local Host: Vivek Dhawan