Circular Polarimetry of Extragalactic Radio Sources

TL;DR

This paper presents multi-frequency circular polarization measurements of four extragalactic radio sources using a novel calibration method, aiming to interpret the circular polarization as Faraday conversion.

Contribution

Introduces a new calibration procedure enabling simultaneous measurement of all Stokes parameters at multiple frequencies with single-dish telescopes.

Findings

Successful multi-frequency polarization measurements obtained.

Data consistent with circular polarization arising from Faraday conversion.

Method improves accuracy of polarization measurements.

Abstract

We report multi-frequency circular polarization measurements for the four extragalactic radio sources 0056-00, 0716+71, 3C138 and 3C161 taken at the Effelsberg 100-m radiotelescope. The data reduction is based on a new calibration procedure that allows the contemporary measurement of the four Stokes parameters at different frequencies with single-dish radiotelescopes. We are in the process of framing the observed full Stokes spectra within a theoretical model that explains that the level of measured circular polarization as Faraday conversion.