A survey of Low Luminosity Compact sources and its implication for evolution of radio-loud AGNs. I. Radio data

TL;DR

This paper introduces a new sample of low luminosity compact radio sources, analyzes their properties, and discusses their potential role as precursors or short-lived phases in the evolution of radio-loud AGNs.

Contribution

It provides the first comprehensive survey of low luminosity CSS sources, revealing their distinct characteristics and evolutionary implications for radio-loud AGNs.

Findings

Approximately 80% of sources are resolved.

About 30% show weak extended emission and disturbed structures.

Many low luminosity CSS sources may be short-lived and precursors to FRI radio galaxies.

Abstract

We present a new sample of Compact Steep Spectrum (CSS) sources with radio luminosity below 10^26 W/Hz at 1.4 GHz called the low luminosity compact (LLC) objects. The sources have been selected from FIRST survey and observed with MERLIN at L-band and C-band. The main criterion used for selection was luminosity of the objects and approximately one third of the CSS sources from the new sample have a value of radio luminosity comparable to FRIs. About 80% of the sources have been resolved and about 30% of them have weak extended emission and disturbed structures when compared with the observations of higher luminosity CSS sources. We studied correlation between radio power and linear size, and redshift with a larger sample that included also published samples of compact objects and large scale FRIIs and FRIs. The low luminosity compact objects occupy the space in radio power versus linear size diagram below the main evolutionary path of radio objects. We suggest that many of them might be short-lived objects, and their radio emission may be disrupted several times before becoming FRIIs. We conclude that there exists a large population of short-lived low luminosity compact objects unexplored so far and part of them can be precursors of large scale FRIs.