The application of compressive sampling to radio astronomy
II. Faraday rotation measure synthesis
Commonwealth Scientific and Industrial Research Organization (CSIRO), Australia
Received: 8 October 2010
Accepted: 16 May 2011
Faraday rotation measure (RM) synthesis is an important tool to study and analyze galactic and extra-galactic magnetic fields. Since there is a Fourier relation between the Faraday dispersion function and the polarized radio emission, full reconstruction of the dispersion function requires knowledge of the polarized radio emission at both positive and negative square wavelengths λ2. However, one can only make observations for λ2 > 0. Furthermore observations are possible only for a limited range of wavelengths. Thus reconstructing the Faraday dispersion function from these limited measurements is ill-conditioned. In this paper, we propose three new reconstruction algorithms for RM synthesis based upon compressive sensing/sampling (CS). These algorithms are designed to be appropriate for Faraday thin sources only, thick sources only, and mixed sources respectively. Both visual and numerical results show that the new RM synthesis methods provide superior reconstructions of both magnitude and phase information than RM-CLEAN.
Key words: methods: data analysis / methods: analytical / polarization / techniques: polarimetric / ISM: magnetic fields
© ESO, 2011