VLBA Imaging Polarimetry of Active Galactic Nuclei - An Automated Approach

Abstract

We present full polarization Very Long Baseline Array (VLBA) observations at 5 GHz and 15 GHz of 24 compact active galactic nuclei (AGN). These sources were observed as part of a pilot project to demonstrate the feasibility of conducting a large VLBI survey to further our understanding of the physical properties and temporal evolution of AGN jets. The sample is drawn from the Cosmic Lens All-Sky Survey (CLASS) where it overlaps with the Sloan Digital Sky Survey at declinations north of 15 degrees. There are 2100 CLASS sources brighter than 50 mJy at 8.4 GHz, of which we have chosen 24 for this pilot study. All 24 sources were detected and imaged at 5 GHz with a typical dynamic range of 500:1, and 21 of 24 sources were detected and imaged at 15 GHz. Linear polarization was detected in 8 sources at both 5 and 15 GHz, allowing for the creation of Faraday rotation measure (RM) images. The core RMs for the sample were found to have an average absolute value of 390 +/- 100 rad/m^2. We also present the discovery of a new Compact Symmetric Object, J08553+5751. All data were processed automatically using pipelines created or adapted for the survey.