Scientists have observed strange activity in Sagittarius A* (Sgr A), the supermassive black hole at the center of the Milky Way galaxy, using the James Webb Space Telescope (JWST). Sgr A, located about 26,000 light-years from Earth and weighing four million times the mass of the Sun, constantly emits mysterious flares that are not yet fully understood.
Astronomers observed Sagittarius A* for a full 48 hours and discovered that the black hole experiences five to six major flares daily, along with several smaller flares between the big bursts. These observations reveal that Sagittarius A* does not follow a clear activity pattern. “We saw changes every time we observed this black hole,” said astronomer Farhad Yusef-Zadeh from Northwestern University. “Sometimes its brightness increases, then suddenly it explodes into a big flare before calming down again. There is no clear pattern; everything seems random.”
Supermassive black holes like Sagittarius A* are often surrounded by an accretion disk—a swirling ring of gas and dust moving at high speeds before being pulled into the black hole. Flares typically occur due to magnetic field collisions or changes in the accretion disk. It is suspected that smaller flares might be caused by disturbances in the plasma orbiting the black hole.
On April 6, 2024, a flare from Sagittarius A* was recorded in mid-infrared wavelengths, a phenomenon never observed before. The detected flare lasted about 40 minutes, followed by a radio flare approximately 10 minutes after the mid-infrared flare. This discovery provides new insights into the behavior of supermassive black holes.
The study on Sagittarius A* was published on February 18, 2025, in The Astrophysical Journal Letters.