Magnetohydrodynamic Turbulence as a Foreground for Cosmic Microwave Background Studies

Abstract

Measurements of the intensity and polarization of diffuse Galactic synchrotron emission as well as starlight polarization reveal power-law spectra of fluctuations. We show that these fluctuations can arise from MHD turbulence in the Galactic disk and halo. To do so, we take into account the converging geometry of lines of sight for the observations when the observer is within the turbulent volume. Assuming that the intensity of turbulence changes along the line of sight, we get a reasonable fit to the observed synchrotron data. As for the spectra of polarized starlight, we get a good fit to the observations taking into account the fact that the observational sample is biased toward nearby stars.