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Water Megamasers and the Hubble Constant

by Dr. L. Humphreys (ESO)

Nov 10, 2014 from 02:30 PM to 04:00 PM

Where IRA meeting room (4th floor, CNR research area, via Gobetti 101)

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Abstract:

Water megamasers at 22 GHz can enable mapping of AGN circumnuclear disks within 1 parsec of supermassive black holes. In combination with either acceleration or proper motion measurements of the masers, purely geometric distances can be obtained. In this talk, I will describe ways in which maser distances are being used to determine the Hubble constant with the aim of high-accuracy (3% uncertainty or better). The first method involves measuring the distance to nearby galaxy NGC 4258, and using it as an anchor to calibrate the standard candle distance scale. The second method involves using maser galaxies in the Hubble Flow to go directly to H_0. I will discuss results from both of these approaches and future prospects.

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