Evidence for Dark Matter in the Milky Way

Learn about evidence for dark matter in the milky way .

There are places where dark matter seems to be a small component or totally absent. Globular clusters show evidence for dark matter with its orbital interactions with galaxies. The compelling evidence for dark matter in the Milky Way is thru the measurements of the velocity profile of stars. However, now it seems that the high concentration of baryonic matter in the disk of the Milky Way galaxy (especially in the interstellar medium) can account for this motion. Galaxy mass profiles are very different from the light profiles. Smooth and spherical distribution in virialized halos is the typical model for dark matter galaxies. Another evidence for dark matter in the milky way is the previously mysterious warp in the disk of the Milky Way by the interaction of the Large and Small Magellanic Clouds and the predicted 20 fold increase in mass of the Milky Way taking into account dark matter.

In 2005, astronomers claimed to discover 50 million light years away in the Virgo Cluster a galaxy VIRGOHI21 made almost entirely of dark matter. VIRGOHI21 does not appear to contain any visible stars: it was seen with radio frequency observations of hydrogen. Using the rotation profiles of VIRGOHI21, the scientists estimate that this object contains approximately 1000 times more dark matter than hydrogen and has a total mass of about 1/10th that of the Milky Way Galaxy.Milky Way Galaxy in comparision is believed to have roughly 10 times as much dark matter as ordinary matter. Big Bang model and structure formation have suggested that such dark galaxies should be very common in the universe. If the existence of this dark galaxy is confirmed, it provides strong evidence for the theory of galaxy formation and poses problems for alternative explanations of dark matter.

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