Two supermassive black holes are about to collide
A new study could change this: researchers are observing a supermassive black hole showing signs of a nearby orbiting companion. The huge duo, called binary, surrounds each other about every two years.
If the team is right, the diameter of the binary's orbit is 10 to 100 times smaller than the only other known supermassive binary, and the pair will merge in approximately 10,000 years. It might seem like a long time, but it would take a total of about 100 million years for black holes of this size to start orbiting each other and finally unite. So this pair is more than 99% of their way to a collision.
Joseph Lazio and Michele Vallisneri, of NASA's Jet Propulsion Laboratory in Southern California, have provided insight into how supermassive black holes behave in a binary system and how to interpret radio data.
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Photo: Depositphotos Evidence that this supermassive black hole may have a companion comes from observations of radio telescopes on Earth. Black holes don't emit light, but their gravity can collect disks of hot gas around them and eject some of that material into space. These jets can span millions of light years. A jet pointed towards the Earth appears much brighter than a jet pointed away from the Earth. Astronomers call supermassive black holes with Earth-oriented jets a blazar, and a blazar called PKS 2131-021 is the focus of this recent paper.
Located approximately 9 billion light-years from Earth, PKS 2131 -021 is one of 1,800 blazars that a group of researchers from Pasadena's Caltech monitored with the Owens Valley Radio Observatory in Northern California for 13 years as part of a general study of the blazar's behavior. But this particular blazar exhibits a strange behavior: its brightness shows regular highs and lows in a predictable way like a clock ticking.
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To confirm that the oscillations were not random or due to a temporary effect around the black hole, the team had to look beyond the decade (from 2008 to 2019) of Owens Valley Observatory data. Upon learning that two other radio telescopes had also studied this system, the University of Michigan Radio Observatory (1980-2012) and Haystack Observatory (1975-1983), they dug into the additional data and found that it matched predictions about how the brightness of the blazar should change over time.
"This work is a testament to the importance of perseverance," said Lazio. “It took 45 years of radio observations to produce this result. Small teams, in different observatories across the country, took the data week after week, month after month, to make it possible. "
