The AGN fuelling/feedback cycle in nearby radio galaxies - I. ALMA
  observations and early results
  This is the first paper of a series exploring the multi-frequency properties
of a sample of eleven nearby low excitation radio galaxies (LERGs) in the
southern sky. We are conducting an extensive study of different galaxy
components (stars, warm and cold gas, radio jets) with the aim of improving our
understanding of the AGN fuelling/feedback cycle in LERGs. We present ALMA Band
6 $^{12}$CO(2-1) and continuum observations of nine sources. Continuum emission
from the radio cores was detected in all objects. Six sources also show mm
emission from jets on kpc/sub-kpc scales. The jet structures are very similar
at mm and cm wavelengths. We conclude that synchrotron emission associated with
the radio jets dominates the continuum spectra up to 230 GHz. The
$^{12}$CO(2-1) line was detected in emission in six out of nine objects, with
molecular gas masses ranging from $2 \times 10^{7}$ to $2 \times 10^{10}$
M$_{\rm \odot}$. The CO detections show disc-like structures on scales from
$\approx$0.2 to $\approx$10 kpc. In one case (NGC 3100) the CO disc presents
some asymmetries and is disrupted in the direction of the northern radio jet,
indicating a possible jet/disc interaction. In IC 4296, CO is detected in
absorption against the radio core, as well as in emission. In four of the six
galaxies with CO detections, the gas rotation axes are roughly parallel to the
radio jets in projection; the remaining two cases show large misalignments. In
those objects where optical imaging is available, dust and CO appear to be
co-spatial.
