Institute for Advanced Study Informal Astrophysics Seminar

Recent, remarkable images made by the EHT collaboration exhibit a ring of emission, presumably orbiting a six billion solar mass black hole. It is proposed that what is observed is not a gas torus but an extensive “ ergomagnetosphere" that connects mechanically to a much larger ``ejection disk’’ and that the powerful jets and the disk are mostly powered by black hole spin, not accretion. Implications for general active galactic nuclei and other sources of relativistic jets will be briefly discussed.