We cross-correlate the Saskatoon Ka- and Q-band cosmic microwave background (CMB) data with different maps to quantify possible foreground contamination. We detect a marginal correlation (≳2 σ) with the Diffuse Infrared Background Experiment (DIRBE) 240, 140, and 100 μm maps, but we find no significant correlation with point sources, with the Haslam 408 MHz map, or with the Reich and Reich 1420 MHz map. The rms amplitude of the component correlated with DIRBE is about 20% of the CMB signal. Interpreting this component as free-free emission, this normalization agrees with that of the 1996 works of Kogut et al. and supports the hypothesis that the spatial correlation between dust and warm ionized gas observed on large angular scales persists to smaller angular scales. Subtracting this contribution from the CMB data reduces the normalization of the Saskatoon power spectrum by only a few percent.
All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics
- Space and Planetary Science
- Cosmic microwave background
- Methods: data analysis