We investigate the extent to which cosmic size magnification may be used to complement cosmic shear in weak gravitational lensing surveys , with a view to obtaining high-precision estimates of cosmological parameters .
Using simulated galaxy images , we find that unbiased estimation of the convergence field is possible using galaxies with angular sizes larger than the Point-Spread Function ( PSF ) and signal-to-noise ratio in excess of 10 .
The statistical power is similar to , but not quite as good as , cosmic shear , and it is subject to different systematic effects .
Application to ground-based data will be challenging , with relatively large empirical corrections required to account for the fact that many galaxies are smaller than the PSF , but for space-based data with 0.1-0.2 arcsecond resolution , the size distribution of galaxies brighter than i \simeq 24 is almost ideal for accurate estimation of cosmic size magnification .