Galaxy Zoo: Stronger bars facilitate quenching in star forming galaxies
  We have used Galaxy Zoo DECaLS (GZD) to study strong and weak bars in disk
galaxies. Out of the 314,000 galaxies in GZD, we created a volume-limited
sample (0.01 < z < 0.05, Mr < -18.96) which contains 1,867 galaxies with
reliable volunteer bar classifications in the ALFALFA footprint. In keeping
with previous Galaxy Zoo surveys (such as GZ2), the morphological
classifications from GZD agree well with previous morphological surveys. GZD
considers galaxies to either have a strong bar (15.5%), a weak bar (28.1%) or
no bar (56.4%), based on volunteer classifications on images obtained from the
DECaLS survey. This places GZD in a unique position to assess differences
between strong and weak bars. We find that the strong bar fraction is typically
higher in quiescent galaxies than in star forming galaxies, while the weak bar
fraction is similar. Moreover, we have found that strong bars facilitate the
quenching process in star forming galaxies, finding higher fibre SFRs, lower
gas masses and shorter depletion timescales in these galaxies compared to
unbarred galaxies. However, we also found that any differences between strong
and weak bars disappear when controlling for bar length. Based on this, we
conclude that weak and strong bars are not fundamentally different phenomena.
Instead, we propose that there is a continuum of bar types, which varies from
'weakest' to 'strongest'.
