Axiverse cosmology and the energy scale of inflation

摘要: Ultralight axions (${m}_{a}\ensuremath{\lesssim}{10}^{\ensuremath{-}18}\text{ }\text{ }\mathrm{eV}$), motivated by string theory, can be a powerful probe of the energy scale inflation. Here it is shown that in contrast to heavier isocurvature modes ultralight coexist with observable gravitational waves. Large-scale structure constraints severely limit parameter space for axion mass, density fraction, and amplitude. It also radically different cosmic microwave background observables mode additionally reduce this space. The results new, accurate, efficient method calculate power spectrum are presented used constrain