December 16, 2017

30.03.10- Fermi: On the Hunt for Dark Matter.

One of the major astrophysical mysteries of our time may be on the verge of being solved. Namely, where is 85% of our universe? That’s the amount that is predicted to be composed of enigmatic dark matter. Now, scientists using NASA’s Fermi Gamma-ray Space Telescope (formerly known as GLAST) have found tantalizing clues at the core of or galaxy; an electron haze thought to be the signature of dark matter annihilations. Fermi passed a milestone of 100 billion detection events with its Large Area Telescope (LAT) last month; such unprecedented sensitivity is giving scientists a new window on the gamma-ray universe. The key is to isolate dark matter sources from other, more “mundane” cosmic events. The tale started back in 2004, when the Wilkinson Microwave Anisotropy Probe (WMAP) began detecting a microwave “haze” centered on the center of our galaxy. Then, just over a year ago, Europe’s Payload for Antimatter Matter Exploration & Light-nuclei Astrophysics (PAMELA) and NASA’s balloon based Advanced Thin Ionization Calorimeter (ATIC) both independently detected high energy positrons and electrons that seemed to emanate from the vicinity of our solar system. This could be explained either by dark matter annihilation or a hidden local dark body source, either conclusion equally bizarre. A good candidate for the Fermi emissions are the annihilation of dark matter neutralinos, which serve as their own anti-particle. The predicted number of neutralino events, however, do not match the quantity of gamma-ray emissions that Fermi sees. Other Earth-bound dark matter detectors are entering the fray, such as the XENON100, and Large Underground Xenon (LUX) dark matter experiment.  Could the puzzle of dark matter be on the verge of an answer soon? Stay tuned…