Black holes are gatherers, not hunters. They waited until an unlucky star hovered. When the star gets close enough, the black hole’s gravity violently tears it apart and devours its gas, releasing intense radiation at the same time.
Astronomers have used NASA’s Hubble Space Telescope to record in detail the final moments of a star being swallowed by a black hole.
These are called “tidal disruption events.” But the wording belies the complex, primal violence that black holes encounter. There is a balance between the black hole’s gravitational pull in of stellar material and the radiation blowing it out. In other words, black holes are messy eaters. Astronomers are using Hubble to learn the details of what happens when a wayward star falls into a gravitational abyss.
Hubble was unable to capture the chaos of the AT2022dsb tidal event up close because the engulfed star lies nearly 300 million light-years from the core of the ESO 583-G004 galaxy. But astronomers have used Hubble’s powerful ultraviolet sensitivity to study light from shattered stars, which include hydrogen, carbon and more. Spectroscopy provides forensic clues to black hole homicide.
Astronomers have detected about 100 TDEs around black holes using a variety of telescopes. NASA recently reported that several of its high-energy space observatories detected another black hole TDE on March 1, 2021, and it happened in another galaxy. Unlike Hubble’s observations, the data were collected in the X-ray light of the extremely hot corona around the black hole that formed after the star had already been ripped apart.
“However, there are still very few tidal events observed in ultraviolet light, given the observation time. This is really unfortunate, because you can get a lot of information from the ultraviolet spectrum,” says Emily Engelthaler from the Center for Astrophysics. Harvard and Smithsonian (CfA) is located in Cambridge, Massachusetts. “We’re excited because we can get these details about what the debris is doing. Tidal events can tell us a lot about the black hole.” Conditions on the doomed star can change over days or months.
For any given galaxy with a quiescent supermassive black hole at its center, stellar debris is estimated to occur only a few times every 100,000 years.
This AT2022dsb star-eating event was first detected on March 1, 2022, by the All-Sky Automated Sky Survey for Supernovae (ASAS-SN or “Assassins”), a network of ground-based telescopes surveying the extragalactic sky about once a week in search of Violent, variable and transient events are shaping our universe. The high-energy collision was close enough to Earth and bright enough that Hubble astronomers could perform ultraviolet spectroscopy for longer than normal.
“Normally, these events are difficult to observe. When it’s really bright, you might get some observations at the beginning of the outage. Our plan is different because it aims to observe some tides during the year events and see what happens,” said CfA’s Peter Maxim. “We see this very early on, we can observe it during these very intense black hole accretion phases. Over time, we see the accretion rate decrease as it becomes a trickle.”
The Hubble spectroscopic data are interpreted to come from very bright, hot, ring-shaped regions of gas that were once stars. This region, known as the torus, is the size of our solar system and orbits the black hole in the middle.
“We’re looking somewhere on the edge of that donut. We’re seeing the stellar wind from the black hole sweeping across the surface, projecting it toward us at 20 million miles per hour (three percent the speed of light),” Maxi said. said Tom. “We’re really still learning about the event. You shred the star, and then it gets the material that goes into the black hole. So you have models, and you think you know what’s going on, and then you get what you actually see. For For scientists, it’s an exciting place to be: right at the border of the known and the unknown.”
The results were reported at the 241st meeting of the American Astronomical Society in Seattle, Washington.