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 ~13 000 deg2 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 integrated Sachs-Wolfe (ISW) effect: for the |b| > 20° sample at l = 6-87, we measure the amplitude (normalized to be 1 for vanilla Λ cold dark matter expectation) of the signal to be 3.4 ± 1.1, i.e. 3.1σ 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. © 2012 The Authors. Monthly Notices of the Royal Astronomical Society © 2012 RAS.