8 papers · 1 filter
Discovery of Water Maser Emission in Eight AGN with 70-m Antennas of NASA's Deep Space Network
P. T. Kondratko, L. J. Greenhill, J. M. Moran +9
We report the discovery of water maser emission in eight active galactic nuclei (AGN) with the 70-m NASA Deep Space Network (DSN) antennas at Tidbinbilla, Australia and Robledo, Sp…
The Geometry of and Mass Accretion Rate through the Maser Accretion Disk in NGC 4258
J. R. Herrnstein, J. M. Moran, L. J. Greenhill +1
A maximum likelihood analysis of the NGC 4258 maser positions and velocities reveals a ~2 sigma deviation from Keplerian motion in the projected rotation curve of the high-velocity…
Probing the Magnetic Field at Sub-Parsec Radii in the Accretion Disk of NGC 4258
Maryam Modjaz, James M. Moran, Paul T. Kondratko +1
We present an analysis of polarimetric observations at 22 GHz of the water vapor masers in NGC 4258 obtained with the VLA and the GBT. We do not detect any circular polarization in…
X-ray Luminosity and Absorption Column Fluctuations in the H2O Maser Galaxy NGC 4258 from Weeks to Years
Antonella Fruscione, Lincoln J. Greenhill, Alexei V. Filippenko +3
We report monitoring of the 0.3-10 keV spectrum of NGC4258 with XMM over 1.5 years.We als o report reprocessing of an overlapping series of archival Chandra observations. By includ…
A Green Bank Telescope Search for Water Masers in Nearby Active Galactic Nuclei
J. A. Braatz, C. Henkel, L. J. Greenhill +2
Using the Green Bank Telescope, we have conducted a survey for 1.3 cm water maser emission toward the nuclei of nearby active galaxies, the most sensitive large survey for H2O mase…
A Warped Accretion Disk and Wide Angle Outflow in the Inner Parsec of the Circinus Galaxy
L. J. Greenhill, R. S. Booth, S. P. Ellingsen +7
We present the first VLBI maps of H2O maser emission (lambda 1.3cm) in the nucleus of the Circinus Galaxy, constructed from data obtained with the Australia Telescope Long Baseline…