A Comparison of Properties of Quasars with and without Rapid Broad
  Absorption Line Variability
  We investigate the correlation between rest-frame UV flux variability of
broad absorption line (BAL) quasars and their variability in BAL equivalent
widths (EWs) in a various timescale from $<10$~days to a few years in the
quasar rest-frame. We use the data sets of BAL EWs taken by the Sloan Digital
Sky Survey Reverberation Mapping (SDSS-RM) project and photometric data taken
by the intermediate Palomar Transient Factory (iPTF) in $g$ and $R$-bands and
the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) in
$grizy$ bands. Our results are summarized as below; (1) the distributions of
flux variability versus BAL variability show weak, moderate, or a strong
positive correlation, (2) there is no significant difference in flux
variability amplitudes between BAL quasar with significant short timescale EW
variability (called class S1) and without (class S2), (3) in all time scales
considered in this paper, the class S1 quasars show systematically larger BAL
variability amplitudes than those of the class S2 quasars, and (4) there are
possible correlations between BAL variability and physical parameters of the
quasars such as black hole masses (moderate positive), Eddington ratios, and
accretion disk temperature (strong negative) in the class S2 quasars. These
results indicate that the BAL variability requires changing in the ionizing
continuum and an ancillary mechanism such as variability in X-ray shielding gas
located at the innermost region of an accretion disk.
