Perhaps the long-suspected black hole has come out of hiding.
A terrifyingly massive black hole in a distant galaxy likely has a smaller companion orbiting it every 12 years. But this tiny partner was never discovered. Now astronomers claim to have seen it for the first time a flash of light emanating directly from a smaller black hole.
“We’ve never seen anything like this before,” astronomer Mauri Valtonen said June 7 at the American Astronomical Society meeting in Albuquerque.
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Astronomers have been watching this object since the 1880s, when it appeared in an asteroid survey as a bright point of light. This point of light, now called OJ287, is a blazar. Among the brightest-looking objects in the universe, blazars are supermassive black holes that shoot bright jets of radiation into space, and these jets are aimed almost directly at Earth. This one is located about 3.5 billion light years away.
Sometimes OJ287 shines even brighter than usual. Over the past 40 years, astronomers have noticed that the brightness of this object increases sharply every 11-12 years.
In 1996, Valtonen and his colleague Harry Lehto, both of the University of Turku in Finland, suggested that the flares could be caused by a single supermassive black hole orbiting an even more massive black hole. Both black holes are likely giants, astronomers estimate, with the smaller one about 150 million times the mass of the Sun and the larger one about 18 billion solar masses. For perspective, the black hole at the center of the Milky Way is about 4 million solar masses.
The larger black hole is thought to be surrounded by a disk of red-hot gas and dust that glows at many wavelengths of light. If a smaller black hole exists, then every time it sinks through this disk, it will cause a flash of light—thus explaining the repeated flares.
This animation shows the flash of light emitted by the smaller supermassive black hole in the blazar OJ287 as it crashes into the disk of gas and dust orbiting the other, more massive black hole it is orbiting.
But so far no light from the very second black hole has been detected. His presence was made only through those regular outbursts.
Valtonen and his colleagues predicted that the last flare should occur in January or February 2022, and arranged to monitor OJ287 daily with telescopes on Earth and in space. The team saw torches similar to the ones they had seen before, but there was a new torch that was different. It was bright and fast, fading after one night.
The team hypothesized that this flare comes from a jet created by a smaller black hole that ejects material from the disk as it approaches the collision.
“It absorbs a lot of disc matter,” Valtonen said. “That matter falls into the secondary black hole and you get a huge flare.”
Previous observations have missed this burst because it is so short. In 2022, the team almost missed it due to bad weather. “We have never observed OJ287 overnight [раніше], it was the first time,” he said. “That’s why we saw it.”
