Predictions on the polarization of extragalactic radio sources at microwave frequencies

Abstract

We present a method to simulate the polarization properties of extragalactic radio sources at microwave frequencies. Polarization measurements of nearly 2×10 6 sources at 1.4 GHz are provided by the NVSS survey. Using this catalogue and the GB6 survey, we study the distribution of the polarization degree of both steep- and flat-spectrum sources. The available high-frequency data are also taken into account in order to extrapolate the distribution of the polarization degree to frequencies higher than 1.4 GHz. Finally, exploiting such information and the evolutionary model by Toffolatti et al. [MNRAS 297 (1998) 117], we find that while extragalactic radio sources can significantly contaminate the CMB E-mode power spectrum only at low frequencies ( ν≲30 GHz), they can severely constrain the detectability of the CMB B-mode up to ν≃100 GHz.