Hubble helps in search for dark energy

Aug. 19, 2010 at 7:51 PM
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PASADENA, Calif., Aug. 19 (UPI) -- U.S. Astronomers say they have a new tool to detect and measure the mysterious dark energy pushing the universe apart at greater and greater speeds.

Space Telescope Science Institute scientists using NASA's Hubble Space Telescope have taken advantage of a giant magnifying "lens" in space -- a massive cluster of galaxies -- to close in on the nature of dark energy, an institute release said.

The observations, combined with data from other methods, significantly increase the accuracy of dark energy measurements and may lead to an explanation of what the elusive phenomenon really is, the researchers say.

Scientists aren't clear about exactly what dark energy is but they know that it makes up about 72 percent of the universe.

"We have to tackle the dark energy problem from all sides," Eric Jullo, an astronomer at NASA's Jet Propulsion Laboratory in Pasadena, Calif., says. "It's important to have several methods, and now we've got a new, very powerful one."

Researchers used images from Hubble to examine a massive cluster of galaxies, named Abell 1689, that acts as a magnifying, or gravitational, "lens." The gravity of the cluster causes galaxies behind it to be imaged multiple times into distorted shapes in the same way a fun-house mirror reflection is a warped image.

Using these distorted images, the scientists can calculate how light from the more distant, background galaxies had been bent by the cluster, a characteristic that depends on the nature of dark energy.

"What I like about our new method is that it's very visual," Jullo said. "You can literally see gravitation and dark energy bend the images of the background galaxies into arcs."

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