Résumé / Abstract Journal-club_Postdoc

Journal-club Postdoc

« Constraints on the Cosmic Neutrino(-like) Background »

Marius Millea

The cosmic background of neutrinos (the CNB) created during the
big bang has been definitively detected via its gravitational influence.
Ongoing measurements are now giving increasingly precise answers to
questions such as 1) what is the energy density contained in the CNB? 2)
what are the masses of the particles making up the CNB? and 3) are these
particles really neutrinos, e.g. do they free-stream like neutrinos? I will
discuss answers to these questions from cosmological probes with particular
focus on the Planck 2015 cosmic microwave background results. Using these
data we've shown for the first time a detection of the phase shift in the
CMB peaks expected from the particular way in which perturbations in the
CNB propagate. I will also explore if there is room left for other
particles to masquerade as part of the CNB, such as axions or axion-like
particles. Recent improvements from Planck and from big bang
nucleosynthesis measurements have been placing increasingly tight
constraints on this scenario.
lundi 26 octobre 2015 - 11:00
Salle des séminaires Évry Schatzman, Institut d'Astrophysique
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