Starship Asterisk*

An excess of high-energy particles hitting Earth may be shrapnel from a stellar explosion 800 light years away.

In the 1930s, it was suggested that supernovae can accelerate galactic cosmic rays. The shock waves from such stellar explosions, or the magnetic fields of the superdense neutron stars left behind, were thought to be able to boost particles from the explosion and surrounding region to very high energies. "But there's been absolutely no evidence for it whatsoever," says Francis Halzen of the University of Wisconsin in Madison, lead scientist for the IceCube detector at the South Pole.

IceCube detects showers of muon particles that cascade towards the Earth when high-energy cosmic rays hit our atmosphere. After analysing the distribution of around 4.3 billion muons detected between June 2007 and March 2008, the IceCube team has found a small but clear excess of cosmic rays coming from the direction of the constellation Vela, hinting that the relatively close Vela supernova remnant may be responsible. "This may be the first strong indication we have" in support of this theory, says Halzen.

• lanl.arXiv.org > astro-ph > arXiv:1005.2960 > 17 May 2010