Results and forecasts on cosmic inflation from weak lensing

Abstract

We highlight the role of weak lensing measurements from current and upcoming stage-IV imaging surveys in the search for cosmic inflation, specifically in measuring the scalar spectral index $n_s$. To do so, we combine the Dark Energy Survey 3 years of observation weak lensing and clustering data with BICEP/Keck, Planck and Sloan Digital Sky Survey data in $r\Lambda$CDM where $r$ is the tensor-to-scalar ratio. While there is no significant improvement in constraining power, we obtain a 1$\sigma$ shift on $n_s$. Additionally, we forecast a weak lensing and clustering data vector from the 10-year Legacy Survey of Space and Time by the Vera C. Rubin Observatory and show its combination with current data would improve their $n_s$ constraints by 25$\%$ in $r\Lambda$CDM.