What is "supermassive black hole"

n. (context astronomy English) Any black hole with a mass 10⁵ to a few times 10¹⁰ times that of the Sun.

A supermassive black hole (SMBH) is the largest type of black hole, in the order of hundreds of thousands to billions of solar masses , and is found in the centre of almost all currently known massive galaxies. In the case of the Milky Way, the SMBH corresponds with the location of Sagittarius A*.

Supermassive black holes have properties that distinguish them from lower-mass classifications. First, the average density of a supermassive black hole (defined as the mass of the black hole divided by the volume within its Schwarzschild radius) can be less than the density of water in the case of some supermassive black holes. This is because the Schwarzschild radius is directly proportional to mass, while density is inversely proportional to the volume. Since the volume of a spherical object (such as the event horizon of a non-rotating black hole) is directly proportional to the cube of the radius, the minimum density of a black hole is inversely proportional to the square of the mass, and thus higher mass black holes have lower average density. In addition, the tidal forces in the vicinity of the event horizon are significantly weaker for massive black holes. As with density, the tidal force on a body at the event horizon is inversely proportional to the square of the mass: a person on the surface of the Earth and one at the event horizon of a 10 million black hole experience about the same tidal force between their head and feet. Unlike with stellar mass black holes, one would not experience significant tidal force until very deep into the black hole.

"Supermassive Black Hole" is a song by English band Muse, featured on their fourth studio album Black Holes and Revelations. It was written by Muse lead singer and principal songwriter Matthew Bellamy. It was released as the lead single from the album in June 2006, backed with "Crying Shame".

The song charted at number four on the UK Singles Chart, the highest singles chart position the band has achieved to date in the United Kingdom. In October 2011, NME placed it at number 74 on its list "150 Best Tracks of the Past 15 Years". It was nominated for the Kerrang! Award for Best Single.