Imaging a Water Maser at z = 0:66


H2O masers are found in about 7% of Type 2 objects in the local universe. They provide information on the nuclear tori and black hole masses of AGNs and have, in one case, been used to make a precise measurement of the distance to an external galaxy (NGC 4258) independent of the usual distance ladder. We have discovered a water maser in the distant universe, from a type 2 quasar at z = 0:66. This is more than an order of magnitude farther away than previously known megamasers. While the spectrum of this object contains but a single spike (at the sensitivity achieved), and thus is not a direct analogue of NGC 4258, its signi cance lies in part in opening up the possibility of nding an object at high-z that can be used to test deviations from the Hubble law inferred from Type Ia supernovae. In this proposal we request time to image this new and unique object, to help determine or constrain the properties of masers in the distant universe, and to test the feasibility of future VLBI on newly discovered weak maser sources.

Name Other * Institution Email Phone
Richard Barvainis PI National Science Foundation (703) 292-4891
Ski Antonucci UCSB (805) 893-4350
Jim Ulvestad NRAO - Socorro
* PI = Principal Investigator; CO = Contact author; T = Thesis observations; S = Student

Front Ends
Gregorian Ku U(12.4 to 15.4 GHz)

Back Ends
VLBA recorder and DAR

Type of Observing
Very Long Baseline Interferometry

Switching Type

Processor (correlator)

Allotted time 6.00 hours

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Updated 09/19/2007