Pointing the National Science Foundation’s Very Large Array (VLA) at a famous galaxy for the first time in two decades, a team of astronomers got a big surprise, finding that a bright new object had appeared near the galaxy’s core. The object, the scientists concluded, is either a very rare type of supernova explosion or, more likely, an outburst from a second supermassive black hole closely orbiting the galaxy’s primary, central supermassive black hole.
Pointing the National Science Foundation’s Very Large Array (VLA) at a famous galaxy for the first time in two decades, a team of astronomers got a big surprise, finding that a bright new object had appeared near the galaxy’s core. The object, the scientists concluded, is either a very rare type of supernova explosion or, more likely, an outburst from a second supermassive black hole closely orbiting the galaxy’s primary, central supermassive black hole.
The astronomers observed Cygnus A, a well-known and often-studied galaxy discovered by radio-astronomy pioneer Grote Reber in 1939. The radio discovery was matched to a visible-light image in 1951, and the galaxy, some 800 million light-years from Earth, was an early target of the VLA after its completion in the early 1980s. Detailed images from the VLA published in 1984 produced major advances in scientists’ understanding of the superfast “jets” of subatomic particles propelled into intergalactic space by the gravitational energy of supermassive black holes at the cores of galaxies.
“This new object may have much to tell us about the history of this galaxy,” said Daniel Perley, of the Astrophysics Research Institute of Liverpool John Moores University in the U.K., lead author of a paper in the Astrophysical Journal announcing the discovery.
“The VLA images of Cygnus A from the 1980s marked the state of the observational capability at that time,” said Rick Perley, of the National Radio Astronomy Observatory (NRAO). “Because of that, we didn’t look at Cygnus A again until 1996, when new VLA electronics had provided a new range of radio frequencies for our observations.” The new object does not appear in the images made then.
Read more at National Radio Astronomy Observatory
Image: Artist's conception of newly-discovered secondary supermassive black hole orbiting the main, central supermassive black hole of galaxy Cygnus A. (Credit: Bill Saxton, NRAO/AUI/NSF)
