Before learning about the topic, let's find out what is dark matter? Dark matter is the invisible material thought to penetrate the universe and can be indirectly detected through its gravitational pull on the normal matter that makes up stars and planets.
The best models of dark matter prepared by the scientists are contradicted by the new measurements made by them which suggests some part of the theoritical model may have to be revised. This complicates the previously complicated mysterious picture of the stuff that is thought to make up 98 percent of all matter in the universe. The model prepared by the scientists, despite not knowing what exactly dark matter is, is a good model to describe its behaviour which envinsions dark matter made up of cold, slow-moving exotic particles that clump together because of gravity.Though the model describes the dark matter's behaviour in most situation, it breaks down when applied to mini "dwarf galaxies," where dark matter appears more spread out than it should be, according to the theory.
According to the model, the ceners of galaxies should be packed with dense clumps of the invisible matter. But in Fornax and Sculptor the dark matter appears to spread evenly throughout, as well as other dwarf galaxies whose mass distributions have been measured in other ways.
Researcher Jorge Penarrubia of England's University of cambridge states that "If a dwrf galaxy were a peach, the standard cosmological model says we should find a dark matter 'pit' at the center. " He adds", Instead, the first two dwarf galaxies we studied are like pitless pitches."
Study leader Matt walker of the Havard-Smithsonian Center for Astrophysics in Cambridge, Mass, said,"Our measurements contradict a basic pediction about the structure of cold dark matter in dwarf galaxies. Unless or untill theorists can modify the prediction, cold dark matter is inconsistent with our observational data."
Dark matter can be easily studied in dwarf galaxies like Fornax and Sculptor , because they are thought to be almost entirely made up of the stuff. Only one percent of matter in a dwarf galaxy is thought to be the normal matter that makes up stars. The researchers studied the motions of 1,500 to 2,500 visible stars, which reflect the gravitational forces acting them from dark matter, to determine where and and how much dark matter inhabits the dwarf galaxies. Some researchers have also suggested that when dark matter interacts with normal matter it may tend to spread out, thus decreasing the density of dark matter in the centers of galaxies. However, so far, this has not been predicted by the cold dark matter model. Researchers give thier statement that either normal matter affects dark matter more than the scientists thought, or it isn't cold and slow-moving.
Walker thus concludes saying,"After completing this study we know less about dark matter than we did before."
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