Speaker
Description
A direct, model-independent probe of the validity of theories beyond General Relativity and the concordance LCDM model is provided by the Weyl potential, the sum of the temporal and spatial distortions of the spacetime geometry. Its measurement, obtained by combining galaxy clustering and galaxy-galaxy lensing data from the Dark Energy Survey (DES-Y3), is in tension with the LCDM prediction at low redshift. Recently, the novel baryon acoustic oscillation measurements from DESI, combined with luminosity distance measurements from type Ia supernovae and Cosmic Microwave Background measurements from Planck, indicated a preference for an evolving dark energy model with an equation of state crossing w=-1. In this talk, I will discuss how the background evolution in evolving dark energy models impacts the growth of the Weyl potential. I will show that evolving dark energy models that cross the phantom divide can naturally reduce the Weyl potential at intermediate redshift, providing a better agreement with DES measurements. These models, however, do not fully capture the measured redshift evolution of the Weyl potential. Further data from Euclid and LSST are then necessary to determine if an evolving dark energy background is enough to explain the low values of the Weyl potential at intermediate redshift, or if the evolution of the perturbations itself should be modified by changing the theory of gravity or by including additional interactions in the dark matter sector.