Radio polarimetry of compact steep spectrum sources at sub-arcsecond resolution

Abstract

Aims. We report new Very Large Array (VLA) polarimetric observations of compact steep-spectrum (CSS) sources at 8.4, 15, and 23 GHz. Methods. Using multi-frequency VLA observations we have derived sub-arcsecond resolution images of the total intensity, polarisation, and rotation measure (RM) distributions.Results. We present multi-frequency VLA polarisation observations of CSS sources. About half of the sources are point-like even at the resolution of ∼0.1 × 0.1 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 ≈5585 rad m −2 . CSS galaxies are characterized by RM values that are larger than CSS quasars. The majority of the objects show very large values of RM. Conclusions. 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 ∼36 000 rad m −2 . RM estimates indicate an overall density of the magneto-ionic medium larger than classical radio sources.

On the Dependence of Spectral Turnover on Linear Size of Compact Steep Spectrum Radio Sources

“…Furthermore, images of some GPS sources show distorted morphologies and the presence of dust, suggesting that mergers and galaxy-galaxy interaction played an important role in these objects [2,3,24,25]. This corroborates the hypothesis that some CSS sources are confined in the dense nuclear region.…”

“…[1,2]. They show double, triple and core-jet morphologies on the radio maps [3]. They have steep high frequency spectrum of spectral index, * ≥ 0.5 , , -∝ / [3 and references therein].…”

Radio properties of Compact Steep Spectrum and GHz‐Peaked Spectrum radio sources

“…Support to the presence of a dense and inhomogeneous medium in front of the radio source comes from the large rotation measure (RM) estimated for those sources with some polarized emission. RM of the order of 1000 rad m −2 or even higher are commonly observed (e.g., O'Dea 1998, Cotton et al 2006, Rossetti et al 2008, Mantovani et al 2013. A different result was found by Mantovani et al (2009) who studied a complete sample of CSS with multifrequency single-dish observations.…”

ALMA Resolves the Stellar Birth Explosion in Distant Quasar 3C298

“…High-resolution imaging (0.1arcsec) with MERLIN revealed that the central radio core breaks up into two components (Akujor et al 1991): a core and jet knot, separated by 0.2arcsec. The radio source has strong spatial radio depolarization inhomogeneity (Mantovani et al 2013). 3C298 is one of the strongest dust emitters in the 3C catalog, with significant Herschel detections at 250, 350 and 500μm (Podigachoski et al 2015).…”