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New light on Dark energy in cosmos

A study shows it stifles galaxy growth as it helps expand the universe.

Stifled? Abell 85, located 740 million years from earth, was one of 86 galaxy clusters observed by NASA's Chandra X-ray Observatory to study dark energy's effects.


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A mysterious form of energy that is speeding the universe's expansion is now showing itself as a cosmic craftsman of sorts.

Astronomers have discovered that the repulsive force known as dark energy sets limits on how large clusters of galaxies can grow.

The new results, based on observations from NASA's Chandra X-Ray Telescope, provide a long-sought confirmation of dark energy's influence on the cosmos. That influence was first discovered serendipitously in the 1990s by astrophysicists studying the expansion rate of the universe. They found the universe's expansion rate was not slowing down as expected, but speeding up.

The new results show that in addition to accelerating the expansion of the universe, dark energy also affects individual structures within the universe.

It does this by allowing fewer galaxy clusters to form.

This "may well be called arrested development," says Alexey Vikhlinin, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., who led the research team.

"We're observing the unambiguous signature of the effects of dark energy on the growth of structure" in the universe.

Over the very long haul, the Chandra results imply that the universe will not end in a "big rip," with everything violently torn apart, as some astrophysicists had speculated. Instead, objects too loosely bound by gravity to overcome the repulsive force of dark energy will gradually vanish into the distance.


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