Probing cosmology with the weak lensing effect of Type Ia Supernovae: A new perspective
We present a method to reconstruct the probability distribution of the weak lensing magnification of Type Ia supernovae (SNe Ia) from observational data. The method is directly applicable to future SNe Ia observed by the Nancy Grace Roman Space Telescope. With a realistic synthetic data set of 13,000 SNe Ia from Roman, all assumed to have spectroscopic redshifts (with follow-up spectroscopy as needed), we show that the weak lensing magnifications can be accurately reconstructed and used to constrain cosmological parameters. This boosts SNe Ia as a cosmological probe by probing both geometrical expansion and growth of cosmological density perturbations.