A hiccuping supermassive black hole has alerted astronomers to an entirely new kind of black hole behavior.
In 2020, at the heart of a galaxy about 800 million light-years from Earth, a black hole with a mass equivalent to 50 million suns suddenly exploded, illuminating the material around it by a factor of 1,000.
A team of researchers thinks these periodic bursts originate from a second, smaller black hole striking the disk of gas and dust surrounding the supermassive black hole, or “accretion disk,” causing it to repeatedly “hiccup” matter.
The findings challenge the traditional picture of how black hole accretion disks work. Previously, scientists believed that these were uniform disks of gas and dust orbiting a central black hole. But the new results suggest that some accretion disks may host exotic components such as stars and even smaller secondary black holes.
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“This is a different beast. It doesn’t fit with anything we know about these systems. We thought we knew a lot about black holes, but this shows us there’s a lot more they can do,” study team member Dheeraj said. “DJ” Pasham, a scientist at the Massachusetts Institute of Technology’s Kavli Institute for Astrophysics and Space Research, said in a statement.
“We think there will be many more systems like this, and we need more data to find them,” Pasham added.
Hunting a ‘different beast’ black hole system
The team first became aware of this hiccuping black hole while examining data from the All Sky Automated Survey for SuperNovae (ASAS-SN), a worldwide network of 20 telescopes that scan the entire sky on Earth once a day.
While ASAS-SN was automatically scanning the sky in December 2020, robotic telescopes spotted a burst of light in a hitherto quiet region of sky containing a galaxy located approximately 800 million light-years away. Pasham tracked this flare using the Neutron Star Interior Composition Explorer (NICER), a NASA X-ray telescope aboard the International Space Station (ISS).
Pasham had only a short time left to use the ISS-based telescope, which is used to detect X-ray bursts from neutron stars, black holes, and other extreme gravitational events in the universe; This meant he had to move quickly and take action. lucky.
“It was either use it or lose it, and it turned out to be the luckiest opportunity for me,” Pasham said.
The researcher found that this galaxy continued to explode, and the explosion lasted for about four months. In NICER observations of this flare, Pasham detected a peculiar pattern of subtle dips in the X-rays and the energy of the burst every 8.5 days. The signal was almost like the dimming of light that occurs when an exoplanet passes or “passes” across the face of its star and briefly blocks the starlight.
“I was scratching my head about what this meant because this model doesn’t fit with anything we know about these systems,” Pasham added.
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Pasham’s confusion was eased when he found research suggesting that a supermassive black hole at the center of a galaxy might be orbited by an intermediate-mass black hole with a mass between 100 and 10,000 times the mass of the Sun.
This smaller black hole may be orbiting the larger one, moving in and out of the supermassive black hole’s accretion disk. As the small black hole passes through this gas and dust, it ejects a cloud of gas. Each dive will create a different plume, hence the periodic pattern of these “hiccups”.
If these clouds are directed toward Earth, they can be seen as a sudden drop in the energy of the affected system as light from the accretion disk is periodically blocked, just as starlight is blocked by a transiting exoplanet.
“I was so excited about this theory that I immediately emailed them and said, ‘I think we’re observing exactly what your theory predicts,'” Pasham added.
This encouraged the authors of the initial study to create simulations incorporating NICER data. These confirmed that the observed 8.5-day signal was likely the result of a small black hole piercing the accretion disk of its larger supermassive black hole companion.
What caused the supermassive black hole to hiccup? too much spaghetti
But this still doesn’t explain why the supermassive black hole suddenly explodes; it just can’t explain why this eruption periodically darkens. The team thinks that this black hole was recently sparked to life by a star that wandered too close to its outer boundary, or “event horizon.”
The enormous gravitational influence of the supermassive black hole will create enormous tidal forces on approaching stars, stretching them vertically and compressing them horizontally in a process called “spaghettification.” This would lead to the star breaking apart in a tidal disruption event, causing a powerful burst of light and a sudden influx of material that would illuminate the accretion disk.
In the newly observed galaxy, the added material apparently fed the supermassive black hole for four months, the duration of the explosion, and also meant that the smaller secondary black hole blew away a larger black hole when it passed through this material. fizzier than ever.
“We see evidence of objects entering and passing through the disk at different angles, challenging the traditional picture of a simple gaseous disk around black holes,” Pasham said. “We think there’s a large population of these systems out there.”
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Richard Saxton is an X-ray astronomer from the European Center for Space Astronomy in Madrid who was not involved in the research. He said the new findings and the technique used to arrive at them could help astronomers better understand supermassive black holes and the exotic environments they inhabit.
“This result suggests that very close supermassive black hole binaries may be common in galactic nuclei, which is a very exciting development for future gravitational wave detectors,” Saxton said in a statement. said. “This is a great example of how to use debris from a shattered star to illuminate the inside of the galactic core, which would otherwise remain dark. It’s like using fluorescent dye to find a leak in a pipe.”
The team’s research was published Wednesday (March 27) in the journal Science Advances.