August 21, 2006

A Dark Matter Shiny!

glaxay cluster

Today's shiny is brought to you by the scientists who have found evidence of dark matter by observing a big cosmic collision. Based on a theory that was described in this 2003 article, scientists have been observing the galaxy cluster 1E0657-556. What they've found confirms that dark matter really does exist.

Clowe and colleagues used NASA's Chandra X-ray Observatory to study the galaxy cluster 1E0657-556, which contains a bullet-shaped cloud of superheated gas. X-rays show the shape was produced by cosmic winds created in a high-speed collision of two clusters of galaxies.

Other telescopes were used to locate and quantify the mass in the clusters. They actually measured the effect of gravitational lensing, in which gravity from the clusters distorts light from thousands of background galaxies, as predicted by Einstein's theory of general relativity.

The dark matter is not seen, but its gravity has a predictable effect on the observations. The resulting blue color in a new image represents the gravity fields observed by noting how the light from each background galaxy is distorted.

Here's what the image reveals:

The hot gas -- normal matter -- was slowed by a drag force described as the cosmic equivalent of air resistance. But the dark matter was not slowed by this effect, presumably because it does not interact with normal matter, as theory had predicted.

So the normal matter and dark matter became separated.

"This proves in a simple and direct way that dark matter exists." Markevitch said in the teleconference.

By confirming that dark matter does actually exist and is a large part of the gravitational field, scientists no longer need to consider some of the other more obscure theories that were being put forward to make up for the unseen matter.

Posted by Mary at August 21, 2006 10:19 PM | Science | Technorati links |

60% of my refridgerator contains dark matter.

Posted by: David Aquarius at August 22, 2006 01:54 AM