TANGO I: ISM in nearby radio galaxies. Molecular gas
  Powerful radio-AGN are hosted by massive elliptical galaxies which are
usually very poor in molecular gas. Nevertheless gas is needed in the very
center to feed the nuclear activity. We aim to study the molecular gas
properties (mass, kinematics, distribution, origin) in such objects, and to
compare them with results of other known samples. We have performed at the
IRAM-30m telescope a survey of the CO(1-0) and CO(2-1) emission in the most
powerful radio galaxies of the Local Universe, selected only on the basis of
their radio continuum fluxes. The main result of our survey is the very low
content in molecular gas of such galaxies compared to spiral or FIR-selected
galaxies. The median value of the molecular gas mass, including detections and
upper limits, is 2.2x10^8 Msun. If separated into FR-I and FR-II types, a
difference in H_2 masses between them is found. The median value of FR-I
galaxies is about 1.9x10^8 and higher for FR-II galaxies, about 4.5x10^8 Msun
but this is very probably entirely due to a Malmquist bias. Our results
contrast with previous surveys, mainly selected through the FIR emission,
implying larger observed masses of molecular gas. Moreover, the shape of CO
spectra suggest the presence of a central molecular gas disk in 30% of these
radio galaxies, a lower rate than in other active galaxy samples.
