Monster Black Holes Spawned Early Galaxies

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Instead of having 700 times more mass than their supermassive black holes, the bulges in the young quasars were only about 30 times more massive.

One possible explanation for this discrepancy between early and late galaxies is that the supermassive black holes formed first and that galaxies essentially "grew around them," study leader Carilli said.

Another possibility is that the galaxies and their supermassive black holes formed at roughly the same time but grew at different rates throughout their histories.

"Maybe we're just seeing a growth spurt of the black holes," Carilli told National Geographic News.

Another Mystery

Astronomers generally agree that supermassive black holes help slow down stellar formation in their galaxies by disrupting gas clouds with their energetic outbursts, preventing them from coalescing into stars.

But the new findings suggest supermassive black holes must also be able to promote stellar growth and help bulk up their host galaxies.

"There are a lot of very good theories about negative feedback, but how you actually get positive feedback, which is required given these measurements, is much less clear," Carilli said.

(Related: "Black Holes Can Spawn Large, Odd Stars, Model Suggests" [August 22, 2008].)

Karl Gebhardt is an astronomer at the University of Texas in Austin who was not involved in the new research.

Gebhardt agreed that the evidence seems to suggest that, at least in the early universe, supermassive black holes formed before their host galaxies. But whether this is also true for later galaxies is still unclear.

"We just don't know what these galaxies that Carilli and company are looking at will turn into," Gebhardt said. "It's going to take a much larger sample to answer that question."

Mateusz Ruszkowski, a black hole researcher at the University of Michigan, also did not participate in the research.

The new finding implies "that black holes waste no time to begin their growth and don't wait for the bulges to catch up until late in the history of the universe," Ruszkowski said.

"This would have serious consequences for the attempts to model galaxy formation and should help to constrain such models."

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