Towards a model of full-sky galactic synchrotron intensity and linear polarisation: A re-analysis of the Parkes data

Abstract

We have analysed the angular power spectra of the Parkes radio continuum and polarisation survey of the Southern galactic plane at 2.4 GHz. We have found that in the multipole range l = 40-250 the angular power spectrum of the polarised intensity is well described by a power-law spectrum with fitted spectral index αL = 2.37 ± 0.21. In the same multipole range the angular power spectra of the E and B components of the polarised signal are significantly flatter, with fitted spectral indices respectively of αE = 1.57 ± 0.12 and αB = 1.45 ± 0.12. Temperature fluctuations in the E and B components are mostly determined by variations in polarisation angle. We have combined these results with other data from available radio surveys in order to produce a full-sky toy model of Galactic synchrotron intensity and linear polarisation at high frequencies (ν ≳ 10 GHz). This can be used to study the feasibility of measuring the Cosmic Microwave Background polarisation with forthcoming experiments and satellite missions.