Statistical properties of Galactic CMB foregrounds: dust and synchrotron

• Published in: Monthly notices of the Royal Astronomical Society Vol. 478; no. 1; pp. 530 - 540
• Main Authors: Kandel, D, Lazarian, A, Pogosyan, D
• Format: Journal Article
• Language: English
• Published: Oxford University Press 21-07-2018
• Subjects: polarization; dust, extinction; turbulence; ISM: magnetic fields
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1093/mnras/sty1115

ABSTRACT
Recent Planck observations have revealed some of the important statistical properties of synchrotron and dust polarization, namely, the B to E mode power and temperature–E (TE) mode cross-correlation. In this paper, we extend our analysis in Kandel et al. that studied the B to E mode power ratio for polarized dust emission to include TE cross-correlation and develop an analogous formalism for synchrotron signal, all using a realistic model of magnetohydrodynamical turbulence. Our results suggest that the Planck results for both synchrotron and dust polarization can be understood if the turbulence in the Galaxy is sufficiently sub-Alfvénic. Making use of the observed poor magnetic field–density correlation, we show that the observed positive TE correlation for dust corresponds to our theoretical expectations. We also show how the B to E ratio as well as the TE cross-correlation can be used to study media magnetization, compressibility, and level of density–magnetic field correlation.