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The Discovery of H2O Maser Emission in Seven Active Galactic Nuclei and at High Velocities in the Circinus Galaxy

journal contribution
posted on 2023-05-16, 19:46 authored by Greenhill, LJ, Kondratko, PT, James LovellJames Lovell, Kuiper, TBH, Moran, JM, Jauncey, DL, Baines, GP
We report the discovery of H2O maser emission at 1.35 cm wavelength in seven active galactic nuclei (at distances of up to 80 Mpc) during a survey conducted at the 70 m diameter antenna of the NASA Deep Space Network near Canberra, Australia. The detection rate was ∼4%. Two of the maser sources are particularly interesting because they display satellite high-velocity emission lines, which are a signature of emission from the accretion disks of supermassive black holes when seen edge-on. Three of the masers are coincident, to within uncertainties of 0″.2, with continuum emission sources that we observed at about λ = 1.3 cm. We also report the discovery of new spectral features in the Circinus galaxy H2O maser that broaden the known velocity range of emission therein by a factor of ∼1.7. If the new spectral features originate in the Circinus accretion disk, then molecular material must survive at radii ∼3 times smaller than had been believed previously (∼0.03 pc or ∼2 × 105 Schwarzschild radii).


Publication title

The Astrophysical Journal








School of Natural Sciences


University of Chicago Press

Place of publication

Chicago, USA

Repository Status

  • Restricted

Socio-economic Objectives

Expanding knowledge in the physical sciences

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