With neutrinos, a new astronomy?

Science magazine announced Friday, November 22 , detections of neutrinos obtained in Antarctica by the IceCube collaboration. We are republishing this occasion chronic Marco Zito had discussed in June the results already presented at a scientific conference.

The peoples of the megaliths, there are several thousands of years, already practiced astronomy , like the great ancient civilizations of China and Egypt . Since these observations have continued and have been a constant source of discoveries about the solar system , our galaxy and the universe. However, these observations were based on the same physical source , electromagnetic waves . It was light at first, then other regions of the spectrum such as radio waves or X-rays
With the observation by the IceCube collaboration neutrinos coming in all probability an astrophysical source , we are entering a new era where the neutrinos are also used to observe the universe. If we consider a very distant source, a photon ( a particle of light) emitted by this source could be absorbed along the way.




The charged particles such as protons can be absorbed or deflected by magnetic fields . Neutrinos , on the contrary , are particles that have the great advantage to interact very little with matter . They could be a messenger of choice for exploring the very distant Universe . A requirement to achieve a detector with a large mass on the order of one billion tonnes. To this end, we can use a natural environment , such as sea water or lake , or ice. Thus, one of these detectors , Antares is located in the depths of the Mediterranean , off Toulon.

The IceCube laboratory located in the Amundsen- Scott station at the South Pole is the largest neutrino detector in the world.
IceCube is one of these non-standard sensors , located at the South Pole and consists of an array of 5,160 photomultiplier poured into ice, at an average depth of 2,000 m. This allows to detect the light emitted by the charged particles produced by neutrino interactions , and this in a cube one kilometer side volume never before .

To calibrate the detector , cosmic rays , consisting among others of very high energy protons are observed. Those whose direction points to the moon are fewer in number because some has been absorbed by our satellite : Shadow of the Moon we see a kind . This verifies the accuracy of the underground of a new type telescope.

Sectional view of the IceCube neutrino detector .
The first results ( arxiv.org/abs/1304.5356 / ) of this effort were presented in 2012. After two years of data taking , there were two events, nicknamed " Ernie " and " Bert " in reference to the characters of the " Muppet Show" . The energy of these two friends is one hundred times greater than that of the bundles of the particle accelerator LHC Geneva . This announcement sparked some curiosity , but was insufficient to draw firm conclusions. New results have recently been shown conference by IceCube collaboration. A new, more sophisticated analysis can detect 28 events in total. If this is confirmed , it would be a new product from an unknown source signal. These events appear to come from the whole sky uniformly.

What could be their origin ? It could be extragalactic objects , which occur very energetic phenomena , perhaps the same people who produce the " gamma-ray bursts " of intense bursts of photons . It could also be interactions or decays of a new particle , which would establish a new mass scale , far beyond the Higgs boson and everything we know. A bright start to a new era of astronomy.

Particle physicist , Commissioner for Atomic Energy and Alternative Energies

Marco Zito