Cross-correlation of WISE Galaxies with the Cosmic Microwave Background

Abstract

We estimated the cross-power spectra of a galaxy sample from the Wide-field Infrared Survey Explorer (WISE) survey with the 7-year Wilkinson Microwave Anisotropy Probe (WMAP) temperature anisotropy maps. A conservatively-selected galaxy sample covers ~13000sq.deg, with a median redshift of z=0.15. Cross-power spectra show correlations between the two data sets with no discernible dependence on the WMAP Q, V and W frequency bands. We interpret these results in terms of the the Integrated Sachs-Wolfe (ISW) effect: for the |b|>20 deg sample at l=6-87, we measure the amplitude (normalized to be 1 for vanilla LambdaCDM expectation) of the signal to be 3.4+-1.1, i.e., 3.1 sigma detection. We discuss other possibilities, but at face value, the detection of the linear ISW effect in a flat universe is caused by large scale decaying potentials, a sign of accelerated expansion driven by Dark Energy.