Black holes

Black holes are the evolutionary endpoints of stars at least 10 to 15 times as massive as the sun. If a stare that massive or larger undergoes a supernova explosion, it may leave behind a fairly massive burned out stellar remnant. With no outward forces to oppose gravitational forces, the remnant will collapse in on itself. The star eventually collapses to the point of zero volume and infinite density. Creating what is known as a singularity around the singularity is a region where the force of gravity is so strong that not even light can escape. Thus, no information can reach us from this region. It is therefore called a black hole.

Astronomers have identified numerous stellar black hole candidates, and have also found evidence of ‘Supermassive black holes’ at the center of galaxies. In 1998, astronomers found compelling evidence that a supermassive black hole of more than 2 million solar masses is located near the Sagittarius A’ region in the center of the Milky way galaxy, and more recent results using additional data find evidence that the supermassive black hole is more than 4 million solar masses.

Once a black hole has formed. It can continue to grow by absorbing additional matter. Any black hole will continually absorb gas and interstellar dust from its direct surroundings and omnipresent cosmic background radiation. This is the primary process through which supermassive black holes seem to have grown. A similar process has been suggested for the formation of intermediate-mass black holes in globular clusters.

Another possibility is for a black hole to merge with other objects such as stars or even other black holes. This is thought to have been important especially for the early development of supermassive black holes, which are thought to have formed for the coagulation of many smaller objects. The process has also been proposed as the origin of some intermediate –mass black holes.

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