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Listen to this articleSupermassive black holeFrom Wikipedia, the free encyclopediaJump to navigationJump to searchThis article is about the astronomical object. For the song by the band Muse, seeSupermassive Black Hole (song).This is the first direct image of a supermassive black hole, located at thegalactic core of Messier 87.[1][2] It shows radio-wave emission from a heatedaccretion ring orbiting the object at a mean separation of 350 AU, or ten timeslarger than the orbit of Neptune around the Sun. The dark center is the eventhorizon and its shadow.[3] The image was released in 2019 by the Event HorizonTelescope Collaboration.A supermassive black hole (SMBH or sometimes SBH)[4] is the largest type of blackhole, with mass on the order of millions to billions of times the mass of the Sun(M). Black holes are a class of astronomical objects that have undergonegravitational collapse, leaving behind spheroidal regions of space from whichnothing can escape, not even light. Observational evidence indicates that almostevery large galaxy has a supermassive black hole at the galaxy's center.[5][6] TheMilky Way has a supermassive black hole in its Galactic Center, which correspondsto the location of Sagittarius A*.[7][8] Accretion of interstellar gas ontosupermassive black holes is the process responsible for powering active galacticnuclei and quasars.[9]Contents1Description2History of research3Formation4Activity and galactic evolution5Evidence5.1Doppler measurements5.2In the Milky Way5.3Outside the Milky Way6Hawking radiation7See also8References9Further reading10External linksDescriptionSupermassive black holes are classically defined as black holes with a mass above0.1 million to 1 million M.[10] Some astronomers have begun labeling black holesof at least 10 billion Mas ultramassive black holes.[11][12] Most of these (suchas TON 618) are associated with exceptionally energetic quasars. Even larger oneshave been dubbed stupendously large black holes (SLAB) with masses greater than 100billion M.[13] Although they noted there is currently no evidence thatstupendously large black holes are real, they noted that supermassive black holesalmost that size do exist.[14] Some studies have suggested that the maximum massthat a black hole can reach, while being luminous accretors, is of the order of ~50billion M.[15][16]Supermassive black holes have physical properties that clearly distinguish themfrom lower-mass classifications. First, the tidal forces in the vicinity of theevent horizon are significantly weaker for supermassive black holes. The tidalforce on a body at a black hole's event horizon is inversely proportional to thesquare of the black hole's mass:[17] a person at the event horizon of a 10 millionMblack hole experiences about the same tidal force between their head and feet asa person on the surface of the earth. Unlike with stellar mass black holes, one
would not experience significant tidal force until very deep into the black hole.

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