Most large galaxies are powered by a supermassive black hole at their core.

Supermassive black holes (SMBHs) are found in the nuclei of almost every large galaxy, including our own Milky Way. Sagittarius A* was first identified as a compact radio source in 1974 by astronomers Bruce Balick and Robert Brown. In 2022, the Event Horizon Telescope collaboration released the first direct image of Sagittarius A*, confirming its mass at roughly 4.3 million times that of our Sun.The relationship between a galaxy and its central black hole is known as the M-sigma relation. This scientific observation shows a direct correlation between the mass of the SMBH and the velocity dispersion of stars in the galaxy's bulge. This suggests that the two evolve together over billions of years through a process called 'active galactic nucleus (AGN) feedback.'As matter falls into the black hole, it forms an accretion disk that heats up to millions of degrees. This process releases massive amounts of radiation and kinetic energy in the form of relativistic jets. These jets heat the surrounding interstellar medium, preventing it from cooling down enough to collapse into new stars. Research from the Hubble Space Telescope and the Chandra X-ray Observatory has shown that this feedback loop is essential for preventing galaxies from growing too large or burning through their fuel too quickly.