Speaker
Description
Scalar fields are widely used in cosmology, in particular to emulate dark energy, for example in quintessence models, or to explain dark matter, in particular within the fuzzy dark matter model. In addition many scenarios involving primordial scalar fields which could have driven inflation or baryogenesis are currently under scrutiny. Here we study the impact of such scalar fields on Big-Bang nucleosynthesis and derive constraints on their parameters using the observed abundance of the elements and try to find set-ups which simultaneously satisfy the helium-4, helium-3, deuterium constraints and the lithium-7 one.
Dark fluid models with scalar fields replacing simultaneously dark matter and dark energy are extremely constrained both by dark matter constraints at local and large scales and by dark energy constraints at cosmological scales. We showed that in the most simple models, no constraints can be obtained from BBN contrary to primordial scalar fields which have decayed during BBN. In this case, they are more likely to have affected the abundance of the elements, in two different ways. First the scalar field density increases the total density and affects the expansion rate of the Universe. Second the decay into radiation injects entropy which modifies the relation between time and temperature and generates a reheating at the BBN epoch.
In my talk, I will present our study of the cosmological evolution of
such scalar fields and show their impact on Big-Bang nucleosynthesis.
