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Gravitational Lensing and Dark Matter
Tony Tyson and Ayana Holloway (Lucent Technologies' Bell Labs/LSST)
Video: 798 kB, Quicktime MOV
According to the General Theory of Relativity, mass warps spacetime. When light travels through space, its path is bent if it passes near a large concentration of matter. Thus, massive objects in the universe can act like huge magnifying glasses, distorting and concentrating light traveling around and through them. This effect is called gravitational lensing and this movie shows how it might work in a cluster of hundreds of galaxies.
Strong gravitational lensing
When light rays from a distant source bend around both sides of a massive object and cross near Earth, the effect is called strong gravitational lensing.
Strong lensing magnifies and distorts light from the source, and in some cases also produces multiple images of the source. This movie shows a simulation of strong lensing by a massive cluster of galaxies containing huge amounts of both visible matter and dark matter. The light distortion effects are exaggerated in the movie, but generally speaking such effects are common since rich clusters of galaxies are the largest concentrations of matter in the universe. In fact, the patterns of distortion help astronomers determine the amount of dark matter in clusters, and how that matter is spread in the cluster, both of which tell a great deal about the behavior of matter in the cosmos as a whole.
Austin Reiter
Tags:
Dark Matter and Galaxy Formation
The Electronic Universe (University of Oregon)
Video: 1001 kB, MPEG
For every gram of matter in the universe that shines or radiates energy, there are between 10 and 100 grams of matter that give off no light at all. This mysterious dark matter
is not made up of atoms or molecules, so scientists can only theorize and speculate about its nature. However, the gravitational effects of dark matter are indisputable and affects the motion and evolution of the largest structures in the universe, including galaxies, clusters, and superclusters. This movie shows how dark matter moves and distributes itself to make certain types of galaxies.
Dark matter and structure development
There is a wide range of galaxy types, shapes and sizes, which means the process of forming galaxies is very complex. In addition, most all galaxies today are embedded in some larger-scale structure. Structure formation could have occurred either from the fragmentation of very large regions into smaller regions, or from the gravitational attraction of small pieces into successively larger structures. Both formation scenarios lead to a highly clustered universe with structure on many different size scales. This particular movie shows how an evenly distributed amount of dark matter, given time, will form structures such as elliptical blobs, webs, and filaments, purely from the force of gravity.
Austin Reiter
