Friday, November 22, 2013

Astronomy is entering a new era

The IceCube laboratory in Antarctica.

November 22, 2013

The first high-energy neutrinos were finally detected after fifty years of research.

The rumor was buzzing from the preliminary results presented in reduced committee last May . The first cosmic neutrinos, direct witnesses of the most energetic events in the Universe , were finally detecIt was nearly fifty years astrophysicists waiting for this news that the official announcement was made on Friday in Science. U.S. IceCube detector , 1 km3 of ice encased sensors buried 2 km depth beneath the South Pole , found 28 of these particles between 2010 and 2012.

"I think we will look in the future this article as a starting point for neutrino astronomy ," enthuses John Carr , director of research at CNRS Centre for Particle Physics of Marseilles and former head of the concurrent program Antares a " neutrino telescope " thirty times smaller plummeted to 2500 m depth in the Mediterranean off the coast of Porquerolles.

They do not "see" the electrons

Detection of a high energy neutrino .
But what this new discipline? Classical astronomy is to look photons, that is to say the light at different wavelengths ( visible range , of course, but also microwave, infrared , ultraviolet, X-rays and gamma) . Problem: photons are easily absorbed by matter. They are struggling to escape from high-density areas such as galactic nuclei or the remnants of exploded stars (also called supernovae ) .

This is not the case of neutrinos. These hardly interact with matter . Since they do not "see" the electrons , they can only be stopped by the atomic nuclei. But if an atom was represented by a football field , the nucleus would be no bigger than a grain of sand. For these particles, the material is almost transparent. If a shade tissue enough to capture about half of the photons emitted by a light bulb , it would lead to a thickness of several billion miles to get the same effect with a bulb neutrino !

" 28 is both very low and very encouraging "

Thierry Stolarczyk , astrophysicist at the CEA