The Sami Galaxy Survey: stellar populations of passive spiral galaxies
  in different environment
  We investigate the stellar populations of passive spiral galaxies as a
function of mass and environment, using integral field spectroscopy data from
the Sydney-AAO Multi-object Integral field spectrograph Galaxy Survey. Our
sample consists of $52$ cluster passive spirals and $18$ group/field passive
spirals, as well as a set of S0s used as a control sample. The age and [Z/H]
estimated by measuring Lick absorption line strength indices both at the center
and within $1R_{\rm e}$ do not show a significant difference between the
cluster and the field/group passive spirals. However, the field/group passive
spirals with log(M$_\star$/M$_\odot)\gtrsim10.5$ show decreasing [$\alpha$/Fe]
along with stellar mass, which is $\sim0.1$ dex smaller than that of the
cluster passive spirals. We also compare the stellar populations of passive
spirals with S0s. In the clusters, we find that passive spirals show slightly
younger age and lower [$\alpha$/Fe] than the S0s over the whole mass range. In
the field/group, stellar populations show a similar trend between passive
spirals and S0s. In particular, [$\alpha$/Fe] of the field/group S0s tend to be
flattening with increasing mass above log(M$_\star$/M$_\odot)\gtrsim10.5$,
similar to the field/group passive spirals. We relate the age and [$\alpha$/Fe]
of passive spirals to their mean infall time in phase-space; we find a positive
correlation, in agreement with the prediction of numerical simulations. We
discuss the environmental processes that can explain the observed trends. The
results lead us to conclude that the formation of the passive spirals and their
transformation into S0s may significantly depend on their environments.
