A VLBI survey of compact broad absorption line quasars with balnicity
  index BI>0
  We performed high resolution radio observations of a new sample of ten BAL
quasars using both the VLBA and EVN at 5 GHz. All the selected sources have
balnicity indices (BI) more than 0 and radio flux densities less than 80 mJy at
1.4 GHz. They are very compact with linear sizes of the order of a few tens of
parsecs and radio luminosities at 1.4 GHz above the FRI-FRII luminosity
threshold. Most of the observed objects have been resolved at 5 GHz showing
one-sided, probably core-jet structures, typical for quasars. We discuss in
detail their age and orientation based on the radio observations. We then used
the largest available sample of BAL quasars to study the relationships between
the radio and optical properties in these objects. We found that (1) the
strongest absorption (high values of the balnicity index BI) is connected with
the lower values of the radio-loudness parameter, logR_I<1.5, and thus probably
with large viewing angles; (2) the large span of the BI values in each bin of
the radio-loudness parameter indicates that the orientation is only one of the
factors influencing the measured absorption; (3) most of the radio-loud BAL
quasars are compact, low luminosity objects with a wide range of jet power
(although the highest values of BI seem to be associated with the lower values
of jet power). In addition, we suggest that the short lifetime postulated for
some compact AGNs could also explain the scarcity of the large-scale radio
sources among BAL quasars.
