THE first deep-space neutrinos to be detected since the 1980s may be the spawn of mystery dark matter. That would explain puzzling features of these particles – and suggest an unusual identity for dark matter.
Neutrinos, ghostly subatomic particles, are routinely produced by the sun and on Earth, but apart from those seen after a 1987 supernova explosion, none had been detected from beyond the solar system.
Then, earlier this year, the IceCube collaboration at the South Pole reported two deep-space neutrinos, dubbed Bert and Ernie, each with a mass of about 1 petaelectronvolt (1015 electronvolts). These were quickly followed by many others with masses of tens of teraelectronvolts (1012 eV), mass and energy being equivalent for particles. However, expected sources of such neutrinos, including energetic explosions called gamma-ray bursts, should also produce neutrinos of other energies.
Pasquale Serpico of the University of Savoy in Annecy-le-Vieux, France, and colleagues wondered if the lack of these other masses could be a sign of decaying dark matter, thought to make up about 80 per cent of the universe's matter.
They calculate that dark matter particles of 1 PeV would decay either directly into neutrinos of around 1 PeV, or into other particles and then into neutrinos with energies of tens of TeV (arxiv.org/abs/1308.1105v1). "It exactly reproduces the features that you see in IceCube," says Serpico.
Several dark matter detectors have reported hints of lightweight particles – but these are not definite detections. Tom Weiler of Vanderbilt University in Nashville, Tennessee, says there is no theoretical reason why dark matter shouldn't be heavy. Or it might come in flavours – light and heavy. Things will become clearer as IceCube amasses more neutrinos and the gaps in energies either persist or vanish.
This article appeared in print under the headline "Did dark matter spawn space neutrinos?"
- New Scientist
- Not just a website!
- Subscribe to New Scientist and get:
- New Scientist magazine delivered every week
- Unlimited online access to articles from over 500 back issues
- Subscribe Now and Save
If you would like to reuse any content from New Scientist, either in print or online, please contact the syndication department first for permission. New Scientist does not own rights to photos, but there are a variety of licensing options available for use of articles and graphics we own the copyright to.