Dark Matter Observed

New evidence for dark matter was announced yesterday. From MSNBC.com:

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 of the clusters. They measured the effect of gravitational lensing, in which gravity from the clusters distorts light from 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 composite image released Monday 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.

So to be clear, the pink is the normal observable matter and the blue represents the gravity fields. You can't have gravity without matter, so this is further evidence for dark matter.