First measurement of $\sigma_8$ using supernova magnitudes only

Understand

A method was recently proposed which allows the conversion of the weak-lensing effects in the supernova Hubble diagram from noise into signal.

• Such signal is sensitive to the growth of structure in the universe, and in particular can be used as a measurement of $\sigma_8$ which is independent from more traditional methods such as those based on the CMB, cosmic shear or cluster abundance.
• We extend here that analysis to allow for intrinsic non-Gaussianities in the supernova PDF, and discuss how this can be best modelled using the Bayes Factor.
• Although it was shown that a precise measurement of $\sigma_8$ requires ~$10^5$ supernovae, current data already allows an important proof of principle.