Does What a Black Hole Eats Affect Its Appearance?

"The gas gobbled up by M87* and Sgr A* (the supermassive black holes at the centers of Messier 87 and the Milky Way), is likely a mix of hydrogen and helium with just a dash of heavier elements, but we don’t know its exact composition. In a new publication, George Wong (Institute for Advanced Study) and Charles Gammie (University of Illinois) pose a relevant question: does the composition of this gas affect the electromagnetic radiation emitted by a supermassive black hole’s accretion disk?"

Read more at AAS Nova