Particle Astrophysics

Particle Astrophysics is the study of how the smallest pieces of matter in the universe interact on a cosmic scale. Scientists believe that by studying particle interactions in space we can better understand why the universe is the way it is. GLAST will probe novel astrophysical phenomena which could arise as a result of new physics beyond our current standard model of particle interactions. It is well established that, like most spiral galaxies, our own galaxy is immersed in a dark halo that outweighs the luminous component by perhaps an order of magnitude. The nature of this dark matter is one of the biggest mysteries in particle physics and cosmology.

Huge amounts of dark matter can cause the light from a distant galaxy to bend around an intervening object. In this case, the light from a galaxy is dispersed and appears as a blue halo, due to the presence of a lensing cluster of galaxies that contains much dark matter.

Huge amounts of dark matter in a cluster of galaxies can cause the light from a distant galaxy to appear as a halo due to gravitational lensing.

One of the leading candidates for the dark matter is a stable, weakly interacting massive particle, or WIMP. In the most plausible models, the mass of the WIMP falls between 10 GeV and 300 GeV. If WIMPs exist in the galactic halo, then they could annihilate and produce gamma rays with photon energies equal to the WIMP mass. These annihilation photons would be observable using GLAST.