Do Bars Drive Spiral Density Waves?
  We present deep near-infrared K_s-band AAT IRIS2 observations of a selected
sample of nearby barred spiral galaxies, including some with the strongest
known bars. The sample covers a range of Hubble types from SB0- to SBc. The
goal is to determine if the torque strengths of the spirals correlate with
those of the bars, which might be expected if the bars actually drive the
spirals as has been predicted by theoretical studies. This issue has
implications for interpreting bar and spiral fractions at high redshift.
Analysis of previous samples suggested that such a correlation exists in the
near-infrared, where effects of extinction and star formation are less
important. However, the earlier samples had only a few excessively strong bars.
Our new sample largely confirms our previous studies, but still any correlation
is relatively weak. We find two galaxies, NGC 7513 and UGC 10862, where there
is a only a weak spiral in the presence of a very strong bar. We suggest that
some spirals probably are driven by their bars at the same pattern speed, but
that this may be only when the bar is growing or if there is abundant gas and
dissipation.
