Cross-correlation of 2MASS and WMAP 3: Implications for the integrated Sachs-Wolfe effect

Abstract

ABSTRACT We perform a cross-correlation of the cosmic microwave background using the third year Wilkinson Microwave Anisotropy Probe (WMAP) data with the Two Micron All Sky Survey (2MASS) galaxy map (about 828 000 galaxies with median redshift). One motivation is to detect the integrated Sachs-Wolfe (ISW) effect, expected if the cosmic gravitational potential is time dependent; for example, as it is in a flat universe with a dark energy component. The measured spherical harmonic cross-correlation signal favours the ISW signal expected in the concordance Lambda cold dark matter (ΛCDM) model over that of zero correlation, although both are consistent with the data within 2σ. Within a flat ΛCDM model we find a best-fitting value of and (95 per cent CL). The above limits assume a galaxy bias, which we derived directly from the 2MASS autocorrelation. Another goal is to test if previously reported anomalies in the WMAP data are related to the galaxy distribution (the so-called 'axis of evil' - AoE). No such anomaly is observed in the 2MASS data nor are there any observed AoE correlations between the 2MASS and WMAP3 data. © 2007 The Authors. Journal compilation © 2007 RAS.