Colin Hill - Early dark energy doesn't make cosmology concordant again скачать в хорошем качестве

Colin Hill - Early dark energy doesn't make cosmology concordant again

Colin tells us about how even though early dark energy can alleviate the Hubble tension, it does so at the expense of increasing other tension. Early dark energy can raise the predicted expansion rate inferred from the cosmic microwave background (CMB), by changing the sound horizon at the last scattering surface. However, the early dark energy also suppresses the growth of perturbations that are within the horizon while it is active. This mean that, to fit the CMB, the matter density must increase (and the spectral index becomes more blue tilted). The consequence is that the matter power spectrum should get bigger. In their paper, Colin and his coauthors show that this affects the weak lensing measurements by DES, KiDS and HSC, and therefore including those experiments in a full data analysis makes things discordant again. The Hubble parameter is pulled back down, restoring most of the tension between local and CMB measurements of H0, and the tension in S_8 gets magnified by the increased mismatch in the predicted and measured matter power spectrum. It is also worth noting that, if you exclude the local measurements of H0, there is no preference for early dark energy in the data. There is hope, perhaps. If the sound horizon could be changed without altering the growth of perturbations that might still be a valid resolution, but it is unlikely to be caused by early dark energy (alone). Colin: http://user.astro.columbia.edu/~jch/ Paper: https://arxiv.org/abs/2003.07355