Particle count at higher energies challenges shock wave–origin scenario
A new census of charged particles buzzing through space includes a puzzling feature that challenges predictions about how these particles originate. The results, presented April 15 at a conference in Geneva, may force scientists to rethink theories that focus on supernovas as the producers of these speedy particles.
Installed on the International Space Station in 2011, the Alpha Magnetic Spectrometer collects and identifies cosmic rays, charged subatomic particles that permeate the galaxy (SN: 3/21/15, p. 22). Based on the previously measured concentrations of galactic cosmic rays, many scientists suspect that the particles get flung toward Earth in the shock waves of exploding stars. But the new analysis of 300 million protons and 50