Cosmic Antimatter Excess Confirmed

sciencehabit writes "In 2008, the Italian satellite PAMELA picked up an unusual signal: a spike in antimatter particles whizzing through space. The discovery, controversial at the time, hinted that physicists might be coming close to detecting dark matter, an enigmatic substance thought to account for 85% of the matter in the universe. Now, new data from NASA's Fermi Gamma-ray Space Telescope confirm the spike (abstract)."

Comments

Re:Dark matter or antimatter?

[justin12345]

"Theorists generally believe that when two dark matter particles collide, they should annihilate each other to produce ordinary particles, such as an electron and its antimatter twin, a positron. Thanks to Einstein's iconic equivalence between energy and mass, E=mc2, each of those particles should emerge with an energy essentially equal to the mass of the original dark matter particle."

I suspect that the author doesn't know that "dark matter" isn't a synonym for "antimatter". The above paragraph, if true, would make the universe a very explode-y place.

Re:Anti-matter vs. dark matter

[sheepe2004]

I'm guessing you didn't RTFA? They are not saying that antimatter is dark matter.

They have detected a large and unexpected amount of antimatter.
Dark matter collisions (theoretically) can create large amounts of antimatter.
So one possible explanation for the antimatter is that two dark matter particles collided.

Re:Dark matter or antimatter?

[Anonymous Coward]

Anything which can produce photons also can produce electron-positron pairs, just with lower probability. However dark matter particles should not produce photons directly because they don't interact electromagnetically (the defining property of dark matter!), and annihilating (directly) into photons would be an electromagnetic interaction (photons are not "pure energy", no matter how often you read that). Rather as weakly interacting particles, I'd expect them to produce virtual Z0s which then could decay into (real) electron-positron pairs, assuming sufficient energy (I'd expect the dominant decay channel to be into neutrinos, though).