A sample of mJy radio sources at 1.4 GHz in the Lynx and Hercules fields - II. Cosmic evolution of the space density of FRI radio sources

Understand

In this paper the cosmic evolution of the space density of Fanaroff & Riley Class I (FRI) radio sources is investigated out to z ~ 1, in order to understand the origin of the differences between these and the more powerful FRIIs.

• High resolution radio images are presented of the best high redshift FRI candidate galaxies, drawn from two fields of the Leiden Berkeley Deep Survey, and previously defined in Rigby, Snellen & Best (2007, Paper I).
• Together with lower resolution radio observations (both previously published in Paper I and, for a subset of sources, also presented here) these are used to morphologically classify the sample.
• Sources which are clearly resolved are classified by morphology alone, whereas barely or unresolved sources were classified using a combination of morphology and flux density loss in the higher resolution data, indicative of resolved out extended emission.