Weak Lensing: Prospects for Measuring Cosmological Parameters

Abstract

Weak lensing of galaxies by large-scale structure can potentially measure cosmological quantities as accurately as the cosmic microwave background (CMB). However, the relation between observables and fundamental parameters is more complex and degenerate, especially in the full space of adiabatic cold dark matter models considered here. We introduce a Fisher matrix analysis of the information contained in weak-lensing surveys to address these issues and provide a simple means of estimating how survey properties and source redshift uncertainties affect parameter measurement. We find that surveys on degree scales and above can improve the accuracy on parameters that affect the growth rate of structure by up to an order of magnitude compared to using the CMB alone, even if the characteristic redshift of the sources must be determined from the data itself. Surprisingly, both sparse sampling and increasing the source redshift can weaken the cosmological constraints.