Variable emission from the Milky Way's supermassive black hole

At the center of our Milky Way lies a supermassive black hole (SMBH) called Sagittarius A* (SgrA*). Supermassive black holes reside at the centers of most galaxies, and when they actively accrete gas and dust onto their surrounding hot disks and environments, they radiate across the electromagnetic spectrum. The mass of SgrA* is about 4 million solar masses, much smaller than the billions of solar-mass SMBHs seen in some galaxies. However, it is relatively close by, only about 25,000 light-years...