Astronomers Catch Supermassive Black Hole Waking Up

Scientists have discovered a supermassive black hole that appears to be "waking up" after being inactive for decades. The black hole at the heart of SDSS1335+0728—a distant galaxy 300 million light-years away—was found to have produced flashes of light known as quasi-periodic eruptions (QPEs). These are "rapid, recurring X-ray bursts from supermassive black holes," the researchers explained in the study published in the journal Nature Astronomy. The first bursts appeared in late 2019, when the galaxy unexpectedly started shining brightly. Following years of study, astronomers have concluded that these changes were a result of the black hole suddenly switching into an active phase. The bright, compact, central portion of the galaxy, known as the active galactic nucleus, was nicknamed "Ansky." "The galaxy SDSS1335+0728, previously stable for two decades, exhibited an increase in optical brightness in December 2019, followed by persistent active galactic nucleus (AGN)-like variability" for five years, suggesting the activation of a supermassive black hole that is a million times the mass of the sun, the researchers noted in the study.

A team led by Lorena Hernández-García, a researcher at the Valparaiso University in Chile and lead author of the latest study, began observing the QPEs from Ansky at nearly regular intervals from February 2024. "This rare event provides an opportunity for astronomers to observe a black hole's behavior in real time," using X-ray space telescopes including the European Space Agency's XMM-Newton and NASA's NICER, Chandra and Swift, Hernández-García said in a statement. She added: "This is the first time we have observed such an event in a black hole that seems to be waking up." XMM-Newton, the only X-ray telescope that can detect the fainter background light between the X-ray bursts, played a pivotal role in the study. "With XMM-Newton we could measure how dim Ansky gets, which enabled us to calculate how much energy Ansky releases when it lights up and starts flashing," Hernández-García explained. The bursts of X-rays from Ansky were found to be 10 times longer and 10 times more luminous than what we see from a typical QPE, noted paper co-author and astrophysicist Joheen Chakraborty of the Massachusetts Institute of Technology in a statement. "Each of these eruptions is releasing a hundred times more energy than we have seen elsewhere. Ansky's eruptions also show the longest cadence ever observed, of about 4.5 days. This pushes our models to their limits and challenges our existing ideas about how these X-ray flashes are being generated." Supermassive black holes are found at the center of most galaxies, which makes them difficult to spot and study. The gravity of a black hole captures matter that get too close and can tear it apart. For example, matter from a captured star would be dispersed into a hot and bright rapidly spinning disc known as an accretion disc. QPEs are currently believed to be caused by an object interacting with an accretion disc. They've been linked to the destruction of a star, but there is no evidence that Ansky has destroyed a star. Since 2019, only a handful more QPE episodes have been detected. "We don't yet understand what causes them," Hernández-García said, noting that "studying Ansky will help us to better understand black holes and how they evolve." Do you have a tip on a science story that Newsweek should be covering? Do you have a question about black holes? Let us know via science@newsweek.com.

Reference

Hernández-García, L., Chakraborty, J., Sánchez-Sáez, P., Ricci, C., Cuadra, J., McKernan, B., Ford, K. E. S., Arévalo, P., Rau, A., Arcodia, R., Kara, E., Liu, Z., Merloni, A., Bruni, G., Goodwin, A., Arzoumanian, Z., Assef, R. J., Baldini, P., Bayo, A., ... Sotomayor, B. (2025). Discovery of extreme quasi-periodic eruptions in a newly accreting massive black hole. Nature Astronomy. https://doi.org/10.1038/s41550-025-02523-9