Key Takeaways:
- NASA's Chandra X-ray Observatory detected a powerful X-ray flare emanating from Sagittarius A* (Sgr A*), the supermassive black hole at the center of the Milky Way galaxy, in October 2000.
- This observation confirmed the existence of Sgr A*, previously inferred from infrared and radio data, resolving prior ambiguity regarding its nature.
- The intensity and sharpness of the Chandra X-ray flare provided definitive evidence of Sgr A*'s active accretion of matter.
- Subsequent Chandra-based research indicated that Sgr A*'s relatively faint X-ray emissions are due to the ejection of a majority of infalling material, with less than 1% reaching the event horizon.
NASA’s Chandra X-Ray Observatory is the agency’s flagship mission for X-ray astronomy. On Sept. 5, 2001, NASA announced that astronomers using Chandra in October of the previous year had witnessed a fast, strong X-ray flare coming from the supermassive black hole at the center of our galaxy. This black hole, named Sagittarius A* (Sgr A*) had long been assumed to be there – infrared and radio observations of the center of the Milky Way had indicated the presence of something large and dark. However, the faintness of the X-ray emissions seen from the supposed black hole puzzled scientists. The sharpness of the imagery from Chandra and the violence of the flare in 2000 dispelled any doubts: There is a supermassive black hole at the center of the Milky Way, and it is actively eating. Research published over a decade later, also based on Chandra observations, would suggest that Sgr A* is faint in X-ray because it ejects most infalling materials – less than 1% make it to the event horizon.
