LSST: a complementary probe of dark energy

Abstract The number of mass clusters and their distribution in redshift are very sensitive to the density of matter ω m and the equation of state of dark energy w . Using weak lens gravitational tomography one can detect clusters of dark matter, weigh them, image their projected mass distribution, and determine their 3-D location. The degeneracy curve in the ω m − w plane is nearly orthogonal to that from CMB or SN measurements. Thus, a combination of CMB data with weak lens tomography of clusters can yield precision measurements of ω m and w , independently of the SN observations. The Large Synoptic Survey Telescope ( LSST ) will repeatedly survey 30,000 square degrees of the sky in multiple wavelengths. LSST will create a 3-D tomography assay of mass overdensities back to half the age of the universe by measuring the shear and color-redshift of billions of high redshift galaxies. By simultaneously measuring several functions of cosmic shear and mass cluster abundance, LSST will provide a number of independent constraints on the dark energy density and the equation of state.