Dark Matter

The effects of dark matter were first noticed in the motion of stars about the center of our Milky Way Galaxy in the 1930’s. The effect of dark matter also seen in gravitational lensing by unseen massive objects. Simulations also showed the condensation of matter to form stars and galaxies, to which we owe our existence, requires a mass density considerably greater than can be accounted for by the visible matter in the Universe.

Dark matter comprises 80% of the mass or our Milky Way Galaxy. Recent observations from the Fermi gamma-ray telescope suggest dark matter is composed of slow-moving particles with a mass of about 30 GeV, about 30 times the mass of a nucleon. These particles are fermions that interact only by the weak force. They are also their own antiparticle. The Fermi telescope sees them by the gamma ray emissions from the rare annihilation events. I will show an image of the Milky Way in 2 GeV photons from dark matter annihilation.