Presentation #101.09 in the session AGN & Quasars — iPoster Session.
Most large galaxies contain supermassive black holes in their centers, and galaxies, as they evolve, merge. It is predicted that, as a result of such a merger, the two galaxies’ central supermassive black holes (SMBHs) sink into the central region of the merger product, forming a binary once their separation approaches parsec scales. A variety of processes can result in the binary hardening and beginning to emit gravitational waves that cause the two SMBHs to spiral together. However, no more than a single clearly-identified sub-parsec SMBH binary is known, and no more than a few candidate SMBH pairs exist with (projected) separations of order 10 pc.
We present multi-frequency Very Long Baseline Array (VLBA) observations of 29 radio sources. These sources were identified as candidate dual active galactic nuclei (AGN) via visual inspection of a much larger database of sources (~ 10,000 sources). Observations occurred at (central) frequencies of 4.2 GHz, 6.5 GHz, and 8.8 GHz, with angular resolutions sufficient to obtain parsec-scale linear resolutions. We summarize the processing pipelines developed and present an initial assessment of sources for which future observations would be warranted.
The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. The North American Nanohertz Observatory for Gravitational Waves (NANOGrav) project receives support from National Science Foundation (NSF) Physics Frontier Center award number 1430284. Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration