The CoNFIG Catalogue - II. Comparison of Space Densities in the FR Dichotomy

TL;DR

This study compares the space densities and evolution of FRI and FRII radio sources using a new, comprehensive catalogue, revealing similar evolutionary patterns and mild evolution for FRI sources across different epochs.

Contribution

It presents the construction of the CoNFIG catalogue with new observations and redshift data, enabling detailed comparison of FRI and FRII source evolution.

Findings

FRI sources show mild evolution over time.

At similar luminosities, FRI and FRII sources have comparable space density enhancements.

The results suggest a possible common evolutionary trend for both source types.

Abstract

This paper focuses on a comparison of the space densities of FRI and FRII sources at different epochs, with a particular focus on FRI sources. First, we present the concluding steps in constructing the Combined NVSS-FIRST Galaxy catalogue (CoNFIG), including new VLA observations, optical identifications and redshift estimates. The final catalogue consists of 859 sources over 4 samples (CoNFIG-1, 2, 3 and 4 with flux density limits of S_1.4GHz = 1.3, 0.8, 0.2 and 0.05 Jy respectively). It is 95.7% complete in radio morphology classification and 74.3% of the sources have redshift data. Combining CoNFIG with complementary samples, the distribution and evolution of FRI and FRII sources are investigated. We find that FRI sources undergo mild evolution and that, at the same radio luminosity, FRI and FRII sources show similar space density enhancements in various redshift ranges, possibly implying a common evolution.