Invisible Active Galactic Nuclei. II Radio Morphologies & Five New HI 21
  cm Absorption Line Detections
  We have selected a sample of 80 candidates for obscured radio-loud active
galactic nuclei and presented their basic optical/near-infrared (NIR)
properties in Paper 1. In this paper, we present both high-resolution radio
continuum images for all of these sources and HI 21cm absorption spectroscopy
for a few selected sources in this sample. A-configuration 4.9 and 8.5 GHz VLA
continuum observations find that 52 sources are compact or have substantial
compact components with size <0.5" and flux density >0.1 Jy at 4.9 GHz. The
most compact 36 sources were then observed with the VLBA at 1.4 GHz. One
definite and 10 candidate Compact Symmetric Objects (CSOs) are newly
identified, a detection rate of CSOs ~3 times higher than the detection rate
previously found in purely flux-limited samples. Based on possessing compact
components with high flux densities, 60 of these sources are good candidates
for absorption-line searches. Twenty seven sources were observed for HI 21cm
absorption at their photometric or spectroscopic redshifts with only 6
detections made (one detection is tentative). However, five of these were from
a small subset of six CSOs with pure galaxy optical/NIR spectra and for which
accurate spectroscopic redshifts place the redshifted 21cm line in a RFI-free
spectral window. It is likely that the presence of ubiquitous RFI and the
absence of accurate spectroscopic redshifts preclude HI detections in similar
sources (only one detection out of the remaining 22 sources observed, 14 of
which have only photometric redshifts). Future searches for highly-redshifted
HI and molecular absorption can easily find more distant CSOs among bright,
blank field' radio sources but will be severely hampered by an inability to
determine accurate spectroscopic redshifts for them due to their lack of
rest-frame UV continuum.
