Séminaire Doctoral / Seminar PhD |
| « A journey in the early Universe: from Neutrino decoupling to Big Bang Nucleosynthesis » |
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Julien Froustey |
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When the temperature of the Universe has dropped to 1 MeV (~ 10^10 K), a great many events take place roughly at the same time. 1) The weak interactions between neutrinos and electrons/positrons become too weak to maintain thermal contact: neutrinos decouple. 2) The temperature reaches the threshold for electron/positron annihilations to take place, which releases considerable amounts of energy transferred to the remaining species. 3) Finally, the temperature becomes low enough for nuclei to be stable enough and the primordial factory of the Universe can produce helium, deuterium, tritium... during the celebrated Big Bang Nucleosynthesis.
In a standard approximation, those phenomena are separated: I will describe how we can more accurately determine both theoretically and numerically the evolution of the different species during this rich era. In particular, I will focus on the evolution of neutrinos and its consequences, which are small but that could be within experimental reach in the coming decades. |
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vendredi 21 février 2020 - 16:00 Salle du Conseil, Institut d'Astrophysique |
| Page web du séminaire / Seminar's webpage |