Supermassive black holes at the nuclei of most galaxies, including our Milky Way, develop gradually as material accretes onto the seed black hole. The physical processes that drive this growth – the so-called feeding and feedback processes – occur in the vicinity of the galaxy nucleus. When the accretion becomes active, radiation is emitted that illuminates and ionizes the gas in the vicinity of the nucleus
An image of the galaxy Markarian 348 in the ultraviolet. Its active nucleus powers outflowing atomic gas, and new observations of it and four similar galaxies have been able to image the outflow as well as a rotating gas component.
25,000 light years from Earth, at the center of our Milky Way Galaxy, a super-massive black hole has so distorted space-time that a cloud of gas, ripped from nearby stars, has stretched and accelerated to more than 1% the speed of light.