Redshifted HI and OH absorption in radio galaxies and quasars
  From a survey for redshifted HI 21-cm and OH 18-cm absorption in the hosts of
a sample of radio galaxies and quasars, we detect HI in three of the ten and OH
in none of the fourteen sources for which useful data were obtained. As
expected from our recent result, all of the 21-cm detections occur in sources
with ultra-violet continuum luminosities of L < 10^23 W/Hz. At these "moderate"
luminosities, we also obtain four non-detections, although, as confirmed by the
equipartition of detections between the type-1 and type-2 objects, this
near-50% detection rate cannot be attributed to unified schemes of active
galactic nuclei (AGN). All of our detections are at redshifts of z < 0.67,
which, in conjunction with our faint source selection, biases against UV
luminous objects. The importance of ultra-violet luminosity (over AGN type) in
the detection of 21-cm is further supported by the non-detections in the two
high redshift z ~ 3.6 - 3.8 radio galaxies, which are both type-2 objects,
while having L > 10^23 W/Hz. Our 21-cm detections in combination with those
previously published, give a total of eight (associated and intervening) HI
absorbing sources searched and undetected in OH. Using the detected 21-cm line
strengths to normalise the limits, we find that only two of these eight may
have been searched sufficiently deeply in OH, although even these are marginal.
