“Even quiet black holes like Sagittarius A* need to blow off some steam.”
INTRODUCTION
Utilizing NASA’s Chandra X-ray Observatory, scientists have identified a novel cosmic “exhaust vent” channeling hot gas away from Sagittarius A* (Sgr A*), the supermassive black hole at the heart of our Milky Way galaxy. Located more than 25,000 light-years from Earth, Sgr A* resides in the constellation Sagittarius and has a mass millions of times greater than our Sun. The discovery, based on data from NASA’s Imaging X-ray Polarimetry Explorer, suggests that Sgr A* awoke approximately 200 years ago to consume cosmic debris. Researchers refer to this black hole as Sgr A* (pronounced “Sagittarius A star”).
DISCOVERY OF THE VENT
The newly discovered vent is linked to a chimney-like formation, oriented perpendicularly to the Milky Way’s disk. Chandra’s observations reveal how a “tunnel” at the galaxy’s center helps channel matter to its outer regions. This vent, located about 700 light-years from the region’s central area, is found at the top of the “chimney.”
An image of the Galactic Center, combining Chandra’s blue X-ray data with red radio-wave data from the South African MeerKAT radio telescope, illustrates the impact of magnetic fields that trap the chimney’s gas. The vent appears as a bright blue and white scar against the darker blue gas in the enhanced image. White ridges of brighter X-rays, visible in Chandra’s data, are theorized to be the walls of a cylindrical tunnel through which hot gas moves upward and away from Sgr A*.
FORMATION AND FUNCTION OF THE VENT
The team behind these observations hypothesizes that the exhaust vent was created by hot gas passing through the chimney and impacting cooler gas, generating shockwaves that brighten the X-ray vent walls. The left side of the vent appears brighter in the image than the right side, likely due to the upward-moving hot gas hitting the left chimney wall more directly and with greater force.
Scientists believe that as material falls towards Sgr A*, the supermassive black hole erupts, pushing matter up through the chimney and out along the vent. However, the frequency of such events remains undetermined.
X-RAY FLARES AND TIDAL DISRUPTION EVENTS
Previous research suggests that Sgr A* and its surroundings experience dramatic X-ray flaring every few centuries. These flares might be crucial in pushing hot gas away from Sgr A*. Additionally, Sgr A* undergoes much rarer feeding events, roughly every 20,000 years, where it tears apart and consumes a star that ventures too close. These occurrences, known as “tidal disruption events” (TDEs), release tremendous energy channeled through the black hole’s chimney along with any stellar material that Sgr A* rejects.
FUTURE RESEARCH AND IMPLICATIONS
The Chandra observations provide a new understanding of how supermassive black holes like Sgr A* interact with their surroundings. By studying the newly discovered vent, researchers aim to gain insights into the mechanisms that allow black holes to consume some matter while expelling other material. These findings could also improve our understanding of the history of activity in the Galactic Center and the processes governing black hole feeding behavior.
A pre-peer-reviewed version of the team’s research on Sgr A* is available on the arXiv paper repository, offering a detailed account of their findings and hypotheses. As further studies continue, these observations promise to shed more light on the dynamic and complex nature of supermassive black holes and their influence on their galactic environments.
