Location of H2O maser in the double-nuclei system of NGC6240

Abstract

We performed VLA observations of the 22 GHz H2O maser emission in the merging galaxy NGC6240, which hosts the well-known double active nuclei. In a previous paper, we reported on the first solid detection of the H2O maser emission in 2001. After two abortive attempts due to the weakness and probable variability of the emission, the maser was detected with the VLA in June 2002. The emission is unresolved at ~ 0.3 arcsecond and coincides with the southern 22 GHz continuum peak to ~ 0.007 arcsecond (~ 3 pc: D = 97 Mpc). The detection of the maser in the southern nucleus indicates that nuclear activity of the galaxy,which is significant in X-ray and far-infrared (FIR) bands, lies mainly in the southern nucleus, and the nucleus without a high brightness peak could be explained by thick dust emitting FIR radiation. We favour the idea that the maser in NGC6240 is associated with the AGN-activity.

arXiv comment7 pages, 2 figues. To appear in Astronomy and Astrophysics (March, issue 2, 2003, vol 400, p457-463)

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• New H2O masers in Seyfert and FIR bright galaxies
• Parsec-Scale Radio Structure of the Double Active Nucleus of NGC 6240
• The Discovery of Water Maser Emission from Eight Nearby Galaxies
• Discovery of Water Maser Emission in Five AGN and a Possible Correlation Between Water Maser and Nuclear 2-10 keV Luminosities
• Nucler star formation in NGC 6240
• A Search for H2O Megamasers in High-z Type-2 AGNs
• Submillimeter H2O Maser in Circinus Galaxy - A New Probe for the Circumnuclear Region of Active Galactic Nuclei
• VLBI Observations of NGC6240: resolving the double nuclei and radio supernovae
• Enhancing the H2O Megamaser Detection Rate Using Optical and Mid-infrared Photometry
• HI and OH Absorption toward NGC6240
• NGC 6240 Supermassive Black Hole Binary dynamical evolution based on Chandra data
• High-Resolution Imaging of Water Maser Emission in the active galaxies NGC 6240 and M51
• Dynamical evolution timescales for the triple supermassive black hole system in NGC 6240
• Two Epochs of Very Large Array Observations of Water Maser Emission in the active galaxy NGC 6240
• Constraints on the presence of water megamaser emission in z~2.5 ultraluminous infrared starburst galaxies