VLBA14B-343
The Megamaser Cosmology Project
Abstract
To constrain models of dark energy, a precise measurement of the Hubble constant provides the best complement to observations of the Cosmic Microwave Background. The Megamaser Cosmology Project (MCP) aims to determine Ho to 3% by measuring geometric distances to water vapor megamasers in the Hubble flow. Based on published observations of UGC 3789 and NGC 6264, the MCP measures Ho = 68.6 +/- 5.6 km/s/Mpc, an 8% result. Including 4 additional preliminary measurements, we determine Ho = 69.0 +/- 3.8 km/s/Mpc (5.5%). We are improving this result by measuring distances to additional galaxies. As a second important science result, the MCP determines the most precise (< 10%) masses of supermassive black holes in external galaxies by measuring the Keplerian rotation curves of masers within a parsec of the black hole. We have determined masses for 17 SMBHs so far, and these measurements are key to understanding the co-evolution of supermassive black holes and their host galaxies. In this proposal we request GBT, HSA, and VLA time to measure the distance to ESO 558-G009, continue our successful survey for additional megamasers in AGNs, and map two newly-discovered maser disks.
Investigators
| Name | Institution |
|---|---|
| Wei Zhao | Shanghai Astronomical Observatory, CAS; Independent |
| Jan Wagner | Max-Planck-Institut für Radioastronomie |
| Mark Reid | Center for Astrophysics | Harvard & Smithsonian |
| Dominic Pesce | Virginia, University of; Smithsonian Astrophysical Observatory |
| Fred K. Y. Lo | National Radio Astronomy Observatory |
| Eugenia Litzinger | Würzburg, Universität |
| Cheng-Yu Kuo | Virginia, University of; National Sun Yat-sen University |
| Violette Impellizzeri | National Radio Astronomy Observatory; Leiden, University of; Joint ALMA Observatory |
| Chris Henkel | Max-Planck-Institut für Radioastronomie |
| Lei Hao | Shanghai Astronomical Observatory, CAS |
| Jenny Greene | Princeton University |
| Feng Gao | Max-Planck-Institut für Radioastronomie |
| Anca Constantin | James Madison University |
| Jim Condon | Independent |
| Jim Braatz * | National Radio Astronomy Observatory |
| GBT Operator | Green Bank Observatory |
| vlbaops vlbaops | National Radio Astronomy Observatory |
| vlbiobs vlbiobs | National Radio Astronomy Observatory |
* indicates the PI