Black Holes

An artist's impression of a black hole with certain characteristic features, including a whirlpool of infalling matter, called an accretion disk. (Image Credit: NASA/Goddard Space Flight Center)

Black holes are astrophysical objects so named because their strong gravitational pull prevents light from escaping a boundary, known as an event horizon. Astronomers have never directly observed a black hole, but the gravitational effects that black holes exert on their cosmic environments reveal certain properties of these objects, such as mass. In 2015, researchers directly detected ripples in the space-time fabric of the universe, known as gravitational waves, for the first time, and which were apparently generated by the collision of two black holes. Altogether, scientists think that black holes come in three basic varieties. One type, called a "stellar" black hole, is created when a giant star collapses at the end of its life. These black holes have a mass of several to tens of times the mass of the Sun, packed into a volume the size of a city, and have been evidenced form indirect observations and gravitational waves. The second type, often dubbed an intermediate black hole, has more than a hundred times the mass of the Sun, and has not been observationally verified to date. The third kind, dubbed a "supermassive" black hole, is found at the heart of nearly all galaxies and can possess a mass of up to billions of times the Sun's. Matter drawn toward these black holes accelerates to high velocities, giving off prodigious, observable energy in the process. In the case of supermassive black holes, the output of energy and winds is so powerful, the objects can play a key role in the evolution of their host galaxies. Overall, black holes are extreme objects that fundamental laws of physics, such as general relativity and quantum mechanics, have failed to explain completely.

Phoenix Rising: A Galaxy Cluster That's Breaking Cosmic Records

Aug 13, 2012
Pheonix cluster

On the eve of their NASA press conference, Michael McDonald, Kavli Institute for Astrophysics and Space Research at MIT, and Bradford Benson, Kavli Institute for Cosmological Physics, University of Chicago, discuss the discovery of the Phoenix Cluster -- a galaxy cluster for the record books.

Tracking Binary Black Holes

Aug 05, 2011
Binary star

Two scientists from the Kavli Institute for Particle Astrophysics and Cosmology have been testing a method to look past the intense radiation pouring out of merging galaxy pairs to see the supermassive black holes at their cores. 

On the GLAST Track

Aug 01, 2007
Gamma Ray Large Area Space Telescope

There’s far more to the universe than meets the eye. Astronomers have long known this, and much of their big-budget work for the past several decades, from radio telescopes to orbiting observatories, has the goal of “seeing” the cosmos on wavelengths that are inaccessible to human sight.

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