At the center of our galaxy, the Milky Way, lies a supermassive black hole named Sagittarius A*.
This black hole, located about 26,000 light-years away from Earth, is blowing its top, and astronomers have now found what appears to be its “exhaust vent.”
Using NASA’s Chandra X-ray Observatory, researchers have observed a long chimney of superheated gas trailing away from the black hole.
They believe these structures are created by eruptions from the supermassive black hole.
This discovery is helping scientists understand what happens around such massive black holes, including how they consume material and expel energy.
“Understanding the movement of material and energy from the Milky Way’s center and its black hole helps us learn more about our galaxy and how galaxies evolve,” said Scott Mackey, a scientist at the University of Chicago who led the study. “We’re really excited to find this new piece of the puzzle.”
How Black Holes Work
Almost all galaxies have a supermassive black hole at their centers. Contrary to popular belief, black holes don’t just suck in everything around them.
Some material near the black hole is blasted off at high speeds. Scientists want to know how much material is expelled, how often this happens, and the process involved.
To learn more, Mackey and his team used NASA’s Chandra X-ray telescope. This telescope, which orbits Earth, is designed to detect X-rays—high-energy light with very short wavelengths.
Astronomers had previously identified a “chimney” of hot material beginning at the galaxy’s center and extending perpendicular to the Milky Way’s spiral disk. They suspected this chimney was formed by strong magnetic fields acting as walls, with hot gas traveling up through it like smoke.
“We now know there’s an exhaust vent near the top of the chimney,” said Mackey, who is a PhD student at UChicago. The newly discovered vent is located about 700 light-years from the galaxy’s center. This means the gas is traveling an enormous distance from the black hole—like an ant flinging something to the height of Mount Everest.
The Black Hole’s Eating Habits
Here’s how scientists think the process works: Occasionally, a star falls into the black hole. But black holes are messy eaters, and some of the material is flung away.
This superheated gas travels up along the chimney at extremely high speeds and out through the exhaust vent. As the hot gas moves, it collides with cooler gas in the chimney, creating shock waves that emit bright X-rays, which the telescope detects.
However, scientists are still unsure how often the black hole is fed. “We don’t know if this energy and heat are caused by a large amount of material being dumped onto Sagittarius A* at once, like a bunch of logs on a fire,” said co-author Mark Morris of the University of California, Los Angeles. “Or it might be from small loads fed into the black hole, like kindling being regularly tossed in.”
The vent might also provide clues about two larger structures near the Milky Way’s center, known as the “Fermi Bubbles” and the “eROSITA Bubbles,” named after the telescopes that discovered them.
These massive bubbles, filled with cosmic rays and gas, could be evidence of a powerful explosion around Sagittarius A* long ago. It’s possible that our galaxy’s center was much more active in the past than it is today.
Other study authors included Konstantina Anastasopoulou from the Italian National Institute of Astrophysics in Palermo, and Gabriele Ponti and Samaresh Mondal from the Italian National Institute of Astrophysics in Merate.
NASA’s Marshall Space Flight Center manages the Chandra program. The Smithsonian Astrophysical Observatory’s Chandra X-ray Center controls science operations from Cambridge, Massachusetts, and flight operations from Burlington, Massachusetts.
This new discovery adds an important piece to the puzzle of understanding our galaxy’s supermassive black hole and the forces at play in the universe.
