Black holes are invisible to us unless they interact with something else.
But other black holes secretly lie in wait for years until a star comes close enough to snack on.
A new study using space and ground-based data from NASA, ESA (European Space Agency), and other institutions describes three extreme examples of supermassive black holes feasting on massive stars.
“One of the biggest questions in astronomy is how black holes grow throughout the universe,” Hinkle said.
But since only 10% of early black holes are actively eating gas and dust, extreme nuclear transients — that is, catching a supermassive black hole in the act of eating a massive star — are a different way to find black holes in the early universe.
We cannot see black holes unless they are in contact with another object. Some seem to glow brightly over time as matter falls in, while they continue to consume gas and dust. However, other black holes covertly wait for years until a star gets close enough to nibble on.
In a recent study, three extreme instances of supermassive black holes consuming massive stars are described using data from NASA, the European Space Agency (ESA), and other organizations. These explosions released more energy than 100 supernovae, making them the most powerful cosmic explosion type yet identified since the big bang.
In the center of a far-off galaxy, each supermassive black hole abruptly became brighter after destroying a star three to ten times heavier than our Sun. After that, the brightness persisted for several months.
These uncommon events are referred to by scientists as “extreme nuclear transients,” a new class of cosmic events. Seeking additional extreme nuclear transients may aid in the discovery of some of the universe’s largest supermassive black holes, which are typically silent.
Jason Hinkle, a University of Hawaii graduate student and the lead author of a recent study detailing this phenomenon in the journal Science Advances, stated that these occurrences are the only way to bring attention to otherwise dormant massive black holes.
Massive amounts of high-energy radiation are released into the central regions of their host galaxies by these events. Hinkle stated, “That has implications for the environments in which these events are occurring.”. It is significant for galaxies if they experience these occurrences. “.”.
The destruction of the stars results in high-energy light that takes more than 100 days to reach its maximum brightness and more than 150 days to dim to half of that brightness. The environment’s reaction to high-energy radiation produces lower-energy emissions that telescopes can also pick up on.
Known as “Barbie” due to its catalog identifier ZTF20abrbeie, one of these star-destroying events was identified in 2020 by Caltech’s Palomar Observatory’s Zwicky Transient Facility and was the subject of two studies in 2023. The new study examines the other two black holes in detail, which were discovered by ESA’s Gaia mission in 2016 and 2018.
The confirmation that these events had to be connected to black holes and not stellar explosions or other phenomena was made possible in large part by NASA’s Neil Gehrels Swift Observatory. The way the optical, ultraviolet, and X-ray light changed brightness over time was similar to a black hole’s fingerprints tearing apart a star.
Data from NASA’s WISE spacecraft, which was in operation from 2009 to 2011 before being reactivated as NEOWISE and retired in 2024, was also utilized by the scientists. The spacecraft used infrared wavelengths to map the sky as part of the WISE mission, discovering numerous new far-off objects and celestial phenomena. Researchers used the spacecraft’s data to describe the dust in each black hole’s surroundings in the new study. The W is one of several ground-based observatories that also helped make this discovery. the NASA-supported Near-Earth Object surveys ATLAS, Pan-STARRS, and Catalina, as well as the M. Keck Observatory telescopes through their archive.
Working with the University of Hawaii 2.2-meter Telescope to search for the chemical fingerprints of these events, Anna Payne, a co-author of the study and a staff scientist at the Space Telescope Science Institute, said, “What I think is so exciting about this work is that we’re pushing the upper bounds of what we understand to be the most energetic environments of the universe.”.
Hinkle’s search for these black hole events was made possible in part by a grant from the agency’s Future Investigators in NASA Earth and Space Science and Technology (FINESST) program. Ben Shappee, an associate professor at the University of Hawaii’s Institute for Astronomy and Hinkle’s advisor and study coauthor, said, “Jason was able to locate and determine what these events were thanks to the FINESST grant.”.
Hinkle will use the NASA Hubble Fellowship Program to pursue these findings as a postdoctoral fellow at the University of Illinois Urbana-Champaign. “How black holes grow throughout the universe is one of the biggest questions in astronomy,” Hinkle stated.
The findings support recent findings from NASA’s James Webb Space Telescope that demonstrate the growth and feeding of supermassive black holes in the early universe. However, since only 10% of early black holes are actively consuming gas and dust, a different method of detecting black holes in the early universe is to observe extreme nuclear transients, which are the result of a supermassive black hole consuming a massive star.
Such events may be observable even in the early, distant universe because they are so bright. The majority of the light emitted by extreme nuclear transients is in the ultraviolet, as Swift demonstrated. NASA’s upcoming Nancy Grace Roman Space Telescope was built to detect the exact type of light that is stretched to longer wavelengths and shifts into the infrared as the universe expands.
Roman’s broad field of view and strong infrared sensitivity will enable it to detect these uncommon explosions from over 12 billion years ago, when the universe was only a tenth of its present age. With a launch date of 2027 and possibly as early as fall 2026, Roman may reveal a lot more of these spectacular occurrences and provide a fresh perspective on the formation and evolution of stars, galaxies, and black holes.
Payne stated, “We can use these three items as a guide to know what to look for in the future.”.
