The stellar kinematics and populations of boxy bulges: cylindrical
  rotation and vertical gradients
  Boxy and peanut-shaped bulges are seen in about half of edge-on disc
galaxies. Comparisons of the photometry and major-axis gas and stellar
kinematics of these bulges to simulations of bar formation and evolution
indicate that they are bars viewed in projection. If the properties of boxy
bulges can be entirely explained by assuming they are bars, then this may imply
that their hosts are pure disc galaxies with no classical bulge. A handful of
these bulges, including that of the Milky Way, have been observed to rotate
cylindrically, i.e. with a mean stellar velocity independent of height above
the disc. In order to assess whether such behaviour is ubiquitous in boxy
bulges, and whether a pure disc interpretation is consistent with their stellar
populations, we have analysed the stellar kinematics and populations of the
boxy or peanut-shaped bulges in a sample of five edge-on galaxies. We placed
slits along the major axis of each galaxy and at three offset but parallel
positions to build up spatial coverage. The boxy bulge of NGC3390 rotates
perfectly cylindrically within the spatial extent and uncertainties of the
data. This is consistent with the metallicity and alpha-element enhancement of
the bulge, which are the same as in the disk. This galaxy is thus a pure disc
galaxy. The boxy bulge of ESO311-G012 also rotates very close to cylindrically.
The boxy bulge of NGC1381 is neither clearly cylindrically nor
non-cylindrically rotating, but it has a negative vertical metallicity gradient
and is alpha-enhanced with respect to its disc, suggesting a composite bulge
comprised of a classical bulge and bar (and possibly a discy pseudobulge)
[abridged] Even this relatively small sample is sufficient to demonstrate that
boxy bulges display a range of rotational and population properties, indicating
that they do not form a homogeneous class of object.
