Gaussianity of Degree‐Scale Cosmic Microwave Background Anisotropy Observations

We present results from a first test of the Gaussianity of degree-scalecosmic microwave background (CMB) anisotropy. We investigate Gaussianity of theCMB anisotropy by studying the topology of CMB anisotropy maps from the QMAPand Saskatoon experiments. We also study the QMASK map, a combination map ofthe QMAP and Saskatoon data. We measure the genus from noise-suppressedWiener-filtered maps at an angular scale of about 1.5 degrees. To test theGaussianity of the observed anisotropy, we compare these results to thosederived from a collection of simulated maps for each experiment in a Gaussianspatially-flat cosmological constant dominated cold dark matter model. Thegenus-threshold level relations of the QMAP and Saskatoon maps are consistentwith Gaussianity. While the combination QMASK map has a mildly non-Gaussiangenus curve which is not a consequence of known foreground contamination, thisresult is not statistically significant at the 2 sigma level. These resultsextend previous upper limits on the non-Gaussianity of the large angular scale(> 10 degrees) CMB anisotropy (measured by the COBE DMR experiment) down todegree angular scales.Comment: 15 pages, 4 figures, Submitted to Ap