Weak Lensing Magnification - A New Window to Cosmology

Hendrik Hildebrandt (UBC)

Weak gravitational lensing (WL) is a unique tool to study the
large-scale mass distribution of the universe since it is sensitive to
both, visible and dark matter (DM). So far, the large-scale structure
has been mainly studied through WL by employing its shear effect. In
this talk I will present a new, complementary method based on the
magnification effect of WL. We measure the cross-correlation functions
of background Lyman-break galaxies (LBGs) selected from the CFHTLS to
foreground lenses selected by accurate photo-z's. The amplitude and
shape of the signal depend on cosmology and on the luminosity function
of the LBGs, and we show that our measurements agree very well with
theoretical expectations. Upcoming measurements on the CFHTLS-Wide
data set will yield the first cosmological constraints from WL
magnification. Furthermore, we study the magnitude-shift effect of
magnification from the same data which will be used to estimate the
profiles of the DM- and dust-halos of galaxies out to z~1.