Has Fermi glimpsed dark matter?

[laconicsax]

http://physicsworld.com/cws/article/news/46033

New results from NASA's Fermi Gamma-Ray Space Telescope appear to confirm a larger-than-expected rate of high-energy positrons reaching the Earth from outer space. This anomaly in the cosmic-ray flux was first observed by the Italian-led PAMELA spacecraft in 2008 and suggests the existence of annihilating dark-matter particles.

Physicists believe that about 80% of the mass in the universe is in the form of a mysterious substance known as dark matter. Unable to observe dark matter using light or other forms of electromagnetic radiation, researchers are attempting to find direct evidence of it on Earth using either heavily shielded underground detectors or with particle accelerators. But they also have a third, less direct, option – using satellites or balloon-based instruments to detect the particles that some theories predict are created in space when two dark-matter particles collide and annihilate.

The Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) mission caused excitement in 2008 after it found significantly larger numbers of positrons (anti-electrons) at energies 10–100 GeV than expected. Taking into consideration only positrons produced when protons interact with the interstellar medium, physicists had calculated that at higher energies there should be a gradual drop in the number of positrons reaching the Earth. However, dark-matter collisions are expected to produce equal numbers of electrons and positrons over a given energy range. This would boost the ratio of positrons to electrons detected because positrons are substantially less abundant than electrons in the universe as a whole.

Much more at link: http://physicsworld.com/cws/article/news/46033

[DetlefK]

1. 2005: hard Gamma-radiation measured during the CGRO/EGRET-mission indicates dark matter

see also:
* W. de Boer et al., The EGRET excess on diffuse galactic gamma rays as tracer of dark matter,
accepted for publication in Astron. Astrophysics, arXiv:astro-ph/0508617. published August 27, 2005

And deBoer gave a talk about this in 2003 already.