Black holes are accelerating the expansion of the Universe, say cosmologists

From the article:

Today cosmologists think some kind of pressure must have forced this acceleration, all powered by huge amounts of energy from an unknown source. Cosmologists call it dark energy. But why this accelerating expansion occurred, and why it happened at that time, is one of the great unsolved mysteries in science.

Now Duncan Farrah and the University of Hawaii in Honolulu and colleagues think they know the answer. They say the acceleration is the result of a previously unknown interaction between black holes and spacetime. When spacetime expands, they say, this interaction makes black holes more massive and this extra mass accelerates the expansion of the universe, creating the accelerated expansion we see today.

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Farrah and co reasoned that if this coupling does occur, then black holes in the early universe would be less massive than those in the more recent past. So they looked for evidence by studying supermassive black holes at the center of galaxies.

It turns out that supermassive black holes in the closer, more recent universe are up to 20 times more massive than those in the more distant, early universe (relative to the mass of the stars around them). “We find evidence for cosmologically coupled mass growth among these black holes,” they say.

This growth cannot be explained by the black holes swallowing nearby stars — there aren’t enough of them. Nor cannot it be explained by the merger of supermassive black holes as galaxies collide, since this would not change the mass ratio of nearby stars.

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The same idea could explain another of cosmology’s great mysteries— why the structure of the universe that we can see seems to be influenced by the gravitational pull of stuff we cannot see, so-called dark matter.

One hypothesized explanation for this is that dark matter takes the form of massive compact halo objects, or MACHOs, that float through interstellar space but do not emit much radiation and so are hard to observe.

Farrah and co’s theory applies to black holes at every scale, from a those few times the mass of our sun to those that are many millions of times bigger. They point out that the smallest black holes form a population that is consistent with properties [of] MACHOs.

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These predictions should be readily testable in the near future. If Farrah and co are correct, then observational conformation of their idea should begin trickling in over the next few months and years.