The origin of radio emission in broad absorption line quasars: Results
  from the LOFAR Two-metre Sky Survey
  We present a study of the low-frequency radio properties of broad absorption
line quasars (BALQSOs) from the LOFAR Two-metre Sky-Survey Data Release 1
(LDR1). The value-added LDR1 catalogue contains Pan-STARRS counterparts, which
we match with the Sloan Digital Sky Survey (SDSS) DR7 and DR12 quasar
catalogues. We find that BALQSOs are twice as likely to be detected at
144$\,$MHz than their non-BAL counterparts, and BALQSOs with low-ionisation
species present in their spectra are three times more likely to be detected
than those with only high-ionisation species. The BALQSO fraction at 144$\,$MHz
is constant with increasing radio luminosity, which is inconsistent with
previous results at 1.4$\,$GHz, indicating that observations at the different
frequencies may be tracing different sources of radio emission. We cross-match
radio sources between the Faint Images of the Radio Sky at Twenty Centimeters
(FIRST) survey and LDR1, which provides a bridge via the LDR1 Pan-STARRS
counterparts to identify BALQSOs in SDSS. Consequently we expand the sample of
BALQSOs detected in FIRST by a factor of three. The LDR1-detected BALQSOs in
our sample are almost exclusively radio-quiet (\logr $\,<2$), with radio sizes
at 144$\,$MHz typically less than $200\,$kpc; these radio sizes tend to be
larger than those at 1.4$\,$GHz, suggesting more extended radio emission at low
frequencies. We find that although the radio detection fraction increases with
increasing balnicity index (BI), there is no correlation between BI and either
low-frequency radio power or radio-loudness. This suggests that both radio
emission and BI may be linked to the same underlying process, but are spatially
distinct phenomena.
