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Research in 2008 indicates that dark matter can produce a weak lensing effect to distort the image of distant galaxies. By noting the degree to which background galaxies appear unusually flat and unusually similar to neighbors, the dark matter distribution producing these weak gravitational lensing distortions can be estimated. Analysis of the shapes of 200,000 distant galaxies imaged does show the presence of a massive network of dark matter. Figure 04-10d is a computer-generated simulation of dark matter distribution. It shows the dark matter (in red) bending the light path from the apparent shape of distant galaxies (in blue) to a more flattened shape. |
Figure 04-10d Dark Matter Lensing [view large image] |
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color hue from blue to red encodes the local velocity dispersion, and the brightness of each pixel is a measurement of the density. In the galaxy evolution panels, each galaxy is weighted by its stellar mass, and the color scale of the images is proportional to the total stellar mass. The cold dark matter evolves from a smooth, nearly uniform distribution into a highly clustered state, quite unlike the galaxies, which are strongly clustered from the beginning. |
Figure 04-11 Cold Dark Matter |