Synopsis: Energetic Neutrinos on Ice

The IceCube detector at the South Pole has observed two of the highest energy neutrinos ever recorded.
Synopsis figure
M. G. Aartsen et al., Phys. Rev. Lett. (2013)

Neutrinos can travel huge distances through obstacles (like interstellar gases) that would stop other particles in their tracks. They are hard to catch, but also potentially good signals of what is going on in galaxies and other things far, far away. In Physical Review Letters, the international IceCube collaboration reports observation of the highest energy neutrinos ever recorded. If confirmed by additional observations, the events could be the iceberg’s tip of a cosmic flux of unusually high-energy neutrinos, unknown until now. These messengers could be carrying information about gamma-ray bursts and active galactic nuclei that may have produced them.

IceCube consists of strings of photomultiplier tubes lowered into boreholes at the South Pole and comprises about one cubic kilometer of ice. Its 5160 detectors are triggered by Cherenkov photons from energetic particles moving through the 2,800-meter-thick polar ice cap. The team recorded two particle showers initiated by neutrinos in which all the collision debris was contained within the detector volume. Adding up the energies of these secondary particles and working backwards, the authors calculated that the energies of the initial neutrinos were above 1 peta-electron-volt (1015 electron volts), about ten orders of magnitude higher than typical neutrinos from the Sun.

The researchers are cautious about claiming too much for only two neutrino observations, discovered in nearly two years of stored IceCube data, but the probability of such events arising from background effects is only 0.29%. Really nailing down whether such events arise from astrophysical sources will require more data. – David Voss


Announcements

More Announcements »

Subject Areas

Astrophysics

Previous Synopsis

Next Synopsis

Nanophysics

Circuit Ready

Read More »

Related Articles

Viewpoint: The Simplicity of Black Holes
Astrophysics

Viewpoint: The Simplicity of Black Holes

The no-hair theorem was originally formulated to describe isolated black holes, but an extended version now describes the more realistic case of a black hole distorted by nearby matter. Read More »

Viewpoint: Weighing Dark Matter Halos with the Cosmic Microwave Background
Astrophysics

Viewpoint: Weighing Dark Matter Halos with the Cosmic Microwave Background

Gravitational lensing by foreground dark matter halos leaves an observable imprint on the cosmic microwave background, which can be used to determine their masses Read More »

Synopsis: Staying Cool in Outer Space
Astrophysics

Synopsis: Staying Cool in Outer Space

In the absence of gravity, surface tension forces affect how fluids flow in heat pipes and may limit the device’s cooling performance on spacecraft missions. Read More »

More Articles