Weak Lensing Probes of the Galaxy-Mass Cross Power Spectrum

The angular correlation function of the background shear-foreground galaxy distribution probes the three dimensional cross power spectrum between mass and galaxies. The same cross power spectrum is also probed when foreground galaxy distribution is cross-correlated with a distribution of background sources disjoint in redshift space. The kernels that project three dimensional clustering to the two dimensional angular space is different for these two probes. When combined, they allow a study of the galaxy-mass cross power spectrum from linear to non-linear scales. By inverting the background shear-foreground galaxy correlation function measured by the Sloan Digital Sky Survey, we present a first estimate of the cross power spectrum between mass and galaxies at low redshifts.