Simulations of Foreground Effects for CMB Polarization

Abstract

We use a simple model to investigate the effect of polarized Galactic foreground emission on the ability of planned CMB missions to detect and model CMB polarization. Emission from likely polarized sources (synchrotron and spinning dust) would dominate the polarization of the microwave sky at frequencies below 90 GHz if known Galactic foregrounds are at least 10% polarized at high latitude (|b| > 30 deg). Maps of polarization at frequencies below 90 GHz will likely require correction for foreground emission to enable statistical analysis of the individual Stokes Q or U components. The temperature-polarization cross-correlation is less affected by foreground emission, even if the foreground polarization is highly correlated with the foreground intensity. Polarized foregrounds, even if uncorrected, do not dominate the uncertainty in the temperature-polarization cross-correlation for instrument noise levels typical of the MAP experiment. Methods which remove galactic signals at the cost of signal to noise ratio should carefully balance the value of rejecting faint foregrounds with the cost of increased instrument noise.