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arXiv · 1705.07901

Discovery of a Luminous Radio Transient 460 pc from the Central Supermassive Black Hole in Cygnus A

Daniel A. Perley·Richard A. Perley·Vivek Dhawan·Christopher L. Carilli
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Abstract

We report the appearance of a new radio source at a projected offset of 460 pc from the nucleus of Cygnus A. The flux density of the source (which we designate Cygnus A-2) rose from an upper limit of <0.5 mJy in 1989 to 4 mJy in 2016 (nu=8.5 GHz), but is currently not varying by more than a few percent per year. The radio luminosity of the source is comparable to the most luminous known supernovae, it is compact in VLBA observations down to a scale of 4 pc, and it is coincident with a near-infrared point source seen in pre-existing adaptive optics and HST observations. The most likely interpretation of this source is that it represents a secondary supermassive black hole in a close orbit around the Cygnus A primary, although an exotic supernova model cannot be ruled out. The gravitational influence of a secondary SMBH at this location may have played an important role in triggering the rapid accretion that has powered the Cygnus A radio jet over the past 10^7 years.

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Daniel A. Perley, Richard A. Perley, Vivek Dhawan, Christopher L. Carilli. 2017-05-25. Discovery of a Luminous Radio Transient 460 pc from the Central Supermassive Black Hole in Cygnus A. https://doi.org/10.3847/1538-4357%2Faa725b

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