Dark Matter Gets Darker

New measurements of tiny galaxies contradict scientists’ best model of dark matter, further complicating the already mysterious picture of the stuff that is thought to make up 98 percent of all matter in the universe. The model suggests dark matter made up of cold, slow-moving exotic particles that clump together because of gravity. In a new study, researchers calculated the mass distribution of two dwarf galaxies using a new method that didn’t rely on any dark matter theories. The scientists studied the Fornax and Sculptor galaxies, which orbit the Milky Way. So their measurements still contradict cold dark matter theory, further entrenching the problem. According to the model, the centers of  galaxies  should  be packed with dense clumps of the invisible  matter.

But dark matter appears to be spread evenly throughout Fornax and Sculptor, as well as other dwarf galaxies whose mass distributions have been measured in other ways. The measurements suggest that some part of the theoretical model may have to be revised. According to study leader Matt Walker of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass their measurements contradict a basic prediction about the structure of cold dark matter in dwarf galaxies. To determine where and how much dark matter inhabits the dwarf galaxies, the researchers studied the motions of 1,500 to 2,500 visible stars, which reflect the gravitational forces acting on them from dark matter. Scientists think that either normal matter affects dark matter more than they thought, or it isn’t cold and slow-moving.

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