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