Comparing the properties of the X-shaped bulges of NGC 4710 and the
  Milky Way with MUSE
  We used the new ESO VLT instrument MUSE to obtain spectral and imaging
coverage of NGC 4710. The wide area and excellent sampling of the MUSE integral
field spectrograph allows us to investigate the dynamical properties of the
X-shaped bulge of NGC 4710 and compare it with the properties of the Milky
Way's own X-shaped bulge. We measured the radial velocities, velocity
dispersion, and stellar populations using a penalized pixel full spectral
fitting technique adopting simple stellar populations models, on a 1' x 1' area
centred on the bulge of NGC 4710. We have constructed the velocity maps of the
bulge of NGC 4710 and we investigated the presence of vertical metallicity
gradients. These properties were compared to those of the Milky Way bulge and
as well as to a simulated galaxy with boxy/peanut bulge. We find the
line-of-sight velocity maps and 1D rotation curves of the bulge of NGC 4710 to
be remarkably similar to those of the Milky Way bulge. Some specific
differences that were identified are in good agreement with the expectations
from variations in the bar orientation angle. The bulge of NGC 4710 has a
boxy-peanut morphology with a pronounced X-shape, showing no indication of any
additional spheroidally distributed bulge population, in which we measure a
vertical metallicity gradient of 0.35 dex/kpc. The general properties of NGC
4710 are very similar to those observed in the MW bulge. However, it has been
suggested that the MW bulge has an additional component that is comprised of
the oldest, most metal-poor stars and which is not part of the boxy-peanut
bulge structure. Such a population is not observed in NGC 4710, but could be
hidden in the integrated light we observed.
