Monster Black Holes Spawned Early Galaxies

Ker Than in Long Beach, California
for National Geographic News
January 8, 2009

Monster black holes served as seeds from which early galaxies sprouted, new research suggests.

The discovery could solve the cosmic chicken-and-egg riddle of which came first—galaxies or the supermassive black holes nestled in their cores.

Supermassive black holes have masses equal to a billion suns or more, and they have been detected at the center of many large galaxies, including our own Milky Way.

Previous studies show an intriguing link between the masses of black holes and the central "bulges" of stars and gas in their resident galaxies.

Regardless of their sizes or ages, the bulges of large galaxies appear to be about 700 times more massive than their central black holes. (See black hole photos.)

"We essentially have no clue as to how this relationship [between galaxies and black holes] is established and when," said study leader Chris Carilli of the National Radio Astronomy Observatory (NRAO).

The research, presented at the American Astronomical Society's meeting in Long Beach, California, indicates that galactic bulges and the monster black holes inside them interact with one another and affect each other's growth.

"The big question has been whether one grows before the other, or if they grow together, maintaining their mass ratio throughout the entire process," study team member Dominik Riechers of Caltech said in a statement.

But the research also raises another mystery: How black holes, which have a very strong gravity, can not only hinder but also promote star and galaxy growth.

Growth Spurt

The team used the Very Large Array radio telescope and the Plateau de Bure Interferometer in France to study galaxies formed during the first billion years of the universe.

The findings showed that bulges in four young galaxies harboring quasars—very energetic supermassive black holes—were much smaller compared to their central black holes than later galaxies.

Continued on Next Page >>




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