Etudes des proprietes des neutrinos dans les contextes ...

tel-00450051, version 1 - 25 Jan 2010
Chapter 3
Neutrinos and core-collapse
supernovae
For massive stars (M ≥ 8 M⊙), the end of the stellar evolution process is inevitably
a gigantic explosion known as the supernova, after which the stellar core
becomes either a neutron star or a black hole. During the explosion about 99%
of the energy released comes out in the form of neutrinos. This is why neutrino
physicists are so interested in supernovae. In their spectrum, neutrinos carry important
information not only about the core-collapse but also about fundamental
properties of neutrinos, some of them being maybe not explorable in accelerators
on Earth. The most recent Supernova near our Galaxy was on the 24th of
February 1987, and was detected with neutrino telescope, namely Kamiokande,
IMB and Baksan. The Supernova, which emerged from a blue supergiant star,
was based in the Large Magellanic Cloud, which is a satellite galaxy of the Milky
Way, at a distance of about 55 Kpc of our solar system. Thanks to the detection
of a few events, the generic features of supernova neutrinos have been roughly
confirmed, namely that the neutrino signal lasts about 10-12 s, with neutrino
energies in the several tens of MeV range. These account for practically all the
gravitational binding energy released in the process of core collapse. Besides, people
have been able to put limits on neutrino properties such as the time decay,
the mass, the magnetic moment or even the electric charge. Here we describe the
main features of core-collapse supernova neutrinos and of the supernova model
we used in our calculations.
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