The angular power spectrum of radio emission at 2.3 GHz

Abstract

We have analysed the Rhodes/HartRAO survey at 2326 MHz and derived the global angular power spectrum of Galactic continuum emission. In order to measure the angular power spectrum of the diffuse component, point sources were removed from the map by median filtering. A least-square fit to the angular power spectrum of the entire survey with a power law spectrum Cl ∝ l-α, gives α = 2.43 ± 0.01 in the l range 2 - 100. The angular power spectrum of radio emission appears to steepen at high Galactic latitudes and for observed regions with |b| > 20°, the fitted spectral index is α = 2.92 ± 0.07. We have extrapolated this result to 30 GHz (the lowest frequency channel of Planck) and estimate that no significant contribution to the sky temperature fluctuation is likely to come from synchrotron at degree-angular scales.