2007MNRAS.377.1668G

We have independently measured the genus topology of the temperature fluctuations in the cosmic microwave background seen in the Wilkinson Microwave Anisotropy Probe (WMAP) 3-yr data. A genus analysis of the WMAP data indicates consistency with Gaussian random-phase initial conditions, as predicted by standard inflation. We set 95 per cent confidence limits on non-linearities of -101 < f_nl< 107. We also find that the observed low-ℓ (ℓ ≤ 8) modes show a slight anticorrelation with the Galactic foreground, but not exceeding 95 per cent confidence, and that the topology defined by these modes is consistent with that of a Gaussian random-phase distribution (within 95 per cent confidence).