Sommaire:

$T^3$ in Grande Ourse*

*tea/coffee/biscuits break around 4pm

Vivian will entertain us pedagogically with The Hubble Tension:
Local measurements of the Hubble parameter (the current expansion rate of our
Universe) from type 1a supernovae disagree at 4.4sigma with the value inferred from a
ΛCDM fit to the cosmic microwave background (CMB), with local measurements
suggesting a higher value. This discrepancy is not easily circumvented by any obvious
systematic effect in either measurement, and so increasing attention is given to the
possibility that this “Hubble tension” indicates new physics beyond ΛCDM. In this tea-time talk, I
would like to (pedagogically) review how one can measure the Hubble constant thanks to
the classical ``distance ladder’’ and the CMB. I will argue that discrepancy in the
Hubble parameter should be interpreted as a tension between our understanding
of the early and late universe cosmology, rather than a tension between two
datasets. I will then explain why it is not trivial (and therefore interesting) to solve this
discrepancy and discuss promising solutions (Early Dark Energy, additional
relativistic degrees of freedom, phantom dark energy...).

Pour plus d'informations, merci de contacter Moultaka G.