An estimate of the local integrated Sachs-Wolfe signal and its impact on cosmic microwave background anomalies

We estimate the local density field in redshift shells to a maximum redshift of z= 0.3, using photometric redshifts for the Two-Micron All-Sky Survey galaxy catalogue, matched to optical data from the SuperCOSMOS galaxy catalogue. This density-field map is used to predict the integrated Sachs–Wolfe (ISW) cosmic microwave background (CMB) anisotropies that originate within the volume at z < 0.3. We investigate the impact of this estimated ISW foreground signal on large-scale anomalies in the Wilkinson Microwave Anisotropy Probe (WMAP) CMB data. We find that removal of the foreground ISW signal from WMAP data reduces the significance of a number of reported large-scale anomalies in the CMB, including the low quadrupole power and the apparent alignment between the CMB quadrupole and octopole.