VLBA16A-216
Completing 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 so far, we measure Ho = 67.6 +/- 4.0 km/s/Mpc, a 6% result. We are improving this result by measuring distances to additional galaxies. Our focus in this proposal is to obtain the GBT, HSA, and VLA observations needed to measure the distance to the spectacular new disk maser in CGCG 074-064, which we discovered in 2015. 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 19 SMBHs so far, and these measurements are key to understanding the co-evolution of supermassive black holes and their host galaxies. Here we also request VLBA+GBT time to map the disk maser in CGCG 165-035. This proposal marks the final observations needed to complete the MCP.
Investigators
| Name | Institution |
|---|---|
| Jim Braatz * | National Radio Astronomy Observatory |
| Dominic Pesce | Virginia, University of; Smithsonian Astrophysical Observatory |
| Anca Constantin | James Madison University |
| Feng Gao | Max-Planck-Institut für Radioastronomie |
| Jenny Greene | Princeton University |
| Lei Hao | Shanghai Astronomical Observatory, CAS |
| Chris Henkel | Max-Planck-Institut für Radioastronomie |
| Violette Impellizzeri | National Radio Astronomy Observatory; Leiden, University of; Joint ALMA Observatory |
| Cheng-Yu Kuo | Virginia, University of; National Sun Yat-sen University |
| Eugenia Litzinger | Würzburg, Universität |
| Fred K. Y. Lo | National Radio Astronomy Observatory |
| Mark Reid | Center for Astrophysics | Harvard & Smithsonian |
| Jan Wagner | Max-Planck-Institut für Radioastronomie |
| Wei Zhao | Shanghai Astronomical Observatory, CAS; Independent |
| Jim Condon | Independent |
* indicates the PI