Effects of Foreground Contamination on the Cosmic Microwave Background Anisotropy Measured by MAP

We study the effects of diffuse Galactic, far-infrared extragalactic source, and radio point source emission on the cosmic microwave background (CMB) anisotropy data anticipated from the MAP experiment. We focus on the correlation function and genus statistics measured from mock MAP foreground-contaminated CMB anisotropy maps generated in a spatially-flat cosmological constant dominated cosmological model. Analyses of the simulated MAP data at 90 GHz (0. 3 FWHM resolution smoothed) show that foreground effects on the correlation function are small compared with cosmic variance. However, the Galactic emission, even just from the region with |b| > 20, significantly affects the topology of CMB anisotropy, causing a negative genus shift non-Gaussianity signal. Given the expected level of cosmic variance, this effect can be effectively reduced by subtracting existing Galactic foreground emission models from the observed data. IRAS and DIRBE far-infrared extragalactic sources have little effect on the CMB anisotropy. Radio point sources raise the amplitude of the correlation function considerably on scales below 0. 5. Removal of bright radio sources above a 5 σ detection limit effectively eliminates this effect. Radio sources also result in a positive genus curve asymmetry (significant at 2 σ) on 0. 5 scales. Accurate radio point source data is essential for an unambiguous detection of CMB anisotropy non-Gaussianity on these scales. Non-Gaussianity of cosmological origin can be detected from the foregroundsubtracted CMB anisotropy map at the 2 σ level if the measured genus shift parameter |∆ν| & 0.02 (0.04) or if the measured genus asymmetry parameter |∆g| & 0.03 (0.08) on a 0. 3 (1. 0) FWHM scale. Subject headings: cosmic microwave background — cosmology: theory Astronomy Program, School of Earth and Environmental Sciences, Seoul National University, 151-742 Korea; [email protected], [email protected]. Department of Physics, Kansas State University, Manhattan, KS 66506; [email protected].