SUPER MASSIVE BLACK HOLE

 A supermassive black hole (SMBH or sometimes SBH)[a] is the largest type of black hole, with its mass being on the order of hundreds of thousands, or millions to billions of times the mass of the Sun (M☉). Black holes are a class of astronomical objects that have undergone gravitational collapse, leaving behind spheroidal regions of space from which nothing can escape, not even light. Observational evidence indicates that almost every large galaxy has a supermassive black hole at its center.

 For example, the Milky Way has a supermassive black hole in its Galactic Center, corresponding to the radio source Sagittarius A.Accretion of interstellar gas onto supermassive black holes is the process responsible for powering active galactic nuclei (AGNs) and quasars.

This is the first direct image of a supermassive black hole, located at the galactic core of Messier 87.It shows radio-wave emission from a heated accretion ring orbiting the object at a mean separation of 350 AU, or ten times larger than the orbit of Neptune around the Sun. The dark center is the event horizon and its shadow.The image was released in 2019 by the Event Horizon Telescope Collaboration.Two supermassive black holes have been directly imaged by the Event Horizon Telescope: the black hole in the giant elliptical galaxy Messier 87 and the black hole at the Milky Way’s center.

For many years, astronomers in the 1900s had only indirect evidence for supermassive black holes, the most compelling of which was the existence of quasars in remote active galaxies. Observations of the energy output and variability timescales of quasars revealed that they radiate over a trillion times as much energy as our Sun from a region about the size of the Solar System. The only mechanism capable of producing such enormous amounts of energy is the conversion of gravitational energy into light by a massive black hole.

More recently, direct evidence for the existence of supermassive black holes has come from observations of material, at the centres of galaxies, rapidly orbiting unseen mass. The high orbital velocities of these stars and gas are easily explained if they are being accelerated by a massive object with a strong gravitational field that is contained within a small region of space – i.e., a supermassive black hole.

                           J.Loshini(2213721033015)