CMB lensing tomography with the DES Science Verification galaxies

Abstract

We measure the cross-correlation between the galaxy density in the Dark\nEnergy Survey (DES) Science Verification data and the lensing of the cosmic\nmicrowave background (CMB) as reconstructed with the Planck satellite and the\nSouth Pole Telescope (SPT). When using the DES main galaxy sample over the full\nredshift range $0.2 < z < 1.2$, a cross-correlation signal is detected at $6\n\\sigma$ and $4\\sigma$ with SPT and Planck respectively. We then divide the DES\ngalaxies into five photometric redshift bins, finding significant ($>$$2\n\\sigma$) detections in all bins. Comparing to the fiducial Planck cosmology, we\nfind the redshift evolution of the signal matches expectations, although the\namplitude is consistently lower than predicted across redshift bins. We test\nfor possible systematics that could affect our result and find no evidence for\nsignificant contamination. Finally, we demonstrate how these measurements can\nbe used to constrain the growth of structure across cosmic time. We find the\ndata are fit by a model in which the amplitude of structure in the $z<1.2$\nuniverse is $0.73 \\pm 0.16$ times as large as predicted in the LCDM Planck\ncosmology, a $1.7\\sigma$ deviation.\n