The galaxy SDSS1335+0728, located 300 million light years away in the constellation Virgo, appears to be experiencing an extraordinary event in real time. In December 2019, scientists realized that this previously unremarkable galaxy had begun to shine brightly. To understand why this was happening, they turned to humanity’s best star-watching tools – including the European Southern Observatory’s (ESO) Very Large Telescope (VLT) and many other ground-based observatories – to get a better look.
After years of study and analysis of the data, a group of researchers has published an article in the journal Astronomy & Astrophysics which details the incredible idea that we are witnessing the awakening of the black hole at the center of a galaxy in real time. Well, technically not in real time, since the light produced by this event is 300 million years old. But like buying a used 2010 Toyota Corolla, it’s new to us.
“Imagine that you have been observing a distant galaxy for years, and it always seemed calm and inactive,” said ESO astronomer Paula Sánchez Sáez in a press release. “Suddenly, his [núcleo] begins to show dramatic changes in brightness, unlike any typical event we have seen before.”
These typical phenomena include supernova explosions or tidal disturbances (TDE), which occur when a star gets too close to a black hole and is completely torn apart. While these extremely violent space phenomena can explain brief bursts of brightness lasting a few dozen to a few hundred days, they cannot explain why SDSS1335+0728 continues to grow brighter than when it was first observed four years ago.
Currently, the most compelling explanation is that scientists are witnessing the “awakening” of a supermassive black hole (which is at least 100,000 times more massive than our Sun) at the center of the galaxy. Combining archival data with new observations – with special credit to the VLT’s X-shooter instrument, described by ESO as “the ultimate weapon in intermediate resolution spectroscopy” – the team discovered that this galaxy was emitting much more energy at ultraviolet, optical and infrared wave than it normally did. Starting in February 2024, the galaxy also began to emit X-rays, a behavior that the research described as “unprecedented.”
Black holes can experience distinct phases of activity and dormancy. When there’s nothing nearby to gobble up, a black hole becomes somewhat dormant, but it can “wake up” to gobble up cosmic material that strays too far away. Another study from June 2023 reported an X-ray echo that pointed to the idea that the Milky Way’s black hole, Sagittarius A* (Sgr A*), had experienced its own flare about 200 years ago.
“These giant monsters are usually sleeping and not directly visible,” Claudio Ricci of Diego Portales University in Chile said in a press release. “This is something that could also happen to our own Sgr A*.”
To completely rule out other alternatives (such as an extremely long TDE), astronomers will have to study SDSS1335+0728 more closely with other instruments on the VLT, as well as take a look through ESO’s upcoming Extremely Large Telescope when it comes online. in 2028. In any case, this galaxy in the Virgo constellation, until now “unremarkable”, is teaching us new things about the most massive objects in the known universe.
Darren lives in Portland, has a cat, and writes/edits about sci-fi and how our world works. You can find his previous stuff from him at Gizmodo and Paste if you look hard enough.
