2013A&A...555A...4M

We report new Very Large Array (VLA) polarimetric observations of compact steep-spectrum (CSS) sources at 8.4, 15, and 23GHz. Using multi-frequency VLA observations we have derived sub-arcsecond resolution images of the total intensity, polarisation, and rotation measure (RM) distributions. We present multi-frequency VLA polarisation observations of CSS sources. About half of the sources are point-like even at the resolution of ∼0.1x0.1-arcsec. The remaining sources have double or triple structure. Low values for the percentage of polarised emission in CSS sources is confirmed. On the average, quasars are more polarised than galaxies. A wide range of RM values have been measured. There are clear indications of very large RMs up to ≃5585rad/m². CSS galaxies are characterized by RM values that are larger than CSS quasars. The majority of the objects show very large values of RM. The available data on sub-arcsecond-scale rest-frame RM estimates for CSS sources show that these have a wide range of values extending up to ∼36000rad/m2. RM estimates indicate an overall density of the magneto-ionic medium larger than classical radio sources.