Duarte Magano
IA & FCUP

Abstract
Observations suggest that the universe is dominated by an energy component whose gravitational behavior is quite similar to that of a cosmological constant. Although a cosmological constant is consistent with existing data, its value would need to be so much smaller that particle physics expectations that a dynamical scalar field is arguably a more likely explanation. If this field couples to the rest of the model, it will lead to potentially observable long-range forces and time dependencies of the constants of nature. In particular, a coupling to the electromagnetic sector will lead to spacetime variations of the
fine-structure constant α.
We discuss a parametrization of the equation of state by Mukhanov, which allows for both freezing and thawing behaviors for dynamical dark energy. We show that it predicts distinct variations of α with redshift, in addition to an evolution of the Hubble parameter which differs from the cosmological constant scenario. Using a combination of background cosmology data (Type Ia supernova and Hubble parameter measurements) and astrophysical and local measurements of α, we obtain new observational constraints for these models, and further discuss how future data may distinguish between the two model classes.

2017 June 20, 15:00

IA/U.Porto
Centro de Astrofísica da Universidade do Porto (Classroom)
Rua das Estrelas, 4150-762 Porto