Broad-band radio polarimetry of the edge-on galaxy NGC 891

We present new results on the polarization properties of the radio continuum halo of NGC 891, an edge-on spiral galaxy often compared to the Milky Way. Using S-band (2–4 GHz) and C-band (4–8 GHz) data from the CHANG-ES survey (Continuum Halos in Nearby Galaxies – an EVLA Survey), we mapped the polarized intensity and applied Rotation Measure synthesis to explore the galaxy's Faraday depth structure. The data reveal extended polarized emission throughout the halo and complex Faraday depth spectra, including multiple components along some lines of sight. To aid interpretation, we compared our results with near-ultraviolet imaging of NGC 891, which traces regions of recent star formation and potential sources of thermal electrons. This comparison suggests a spatial relationship between polarized features and areas of enhanced UV emission. Our findings highlight the value of combining broadband polarimetry and multi-wavelength data in studying the magneto-ionic environments of spiral galaxy halos.