Evidence for non-axisymmetry in M31 from wide-field kinematics of stars
  and gas
  As the nearest large spiral galaxy, M31 provides a unique opportunity to
learn about the structure and evolutionary history of this galaxy type in great
detail. Among the many observing programs aimed at M31 are microlensing
studies, which require good three-dimensional models of the stellar mass
distribution. Possible non-axisymmetric structures like a bar need to be taken
into account. Due to M31's high inclination, the bar is difficult to detect in
photometry alone. Therefore, detailed kinematic measurements are needed to
constrain the possible existence and position of a bar in M31. We obtained
$\approx$ 220 separate fields with the optical IFU spectrograph VIRUS-W,
covering the whole bulge region of M31 and parts of the disk. We derive stellar
line-of-sight velocity distributions from the stellar absorption lines, as well
as velocity distributions and line fluxes of the emission lines H$\beta$,
[OIII] and [NI]. Our data supersede any previous study in terms of spacial
coverage and spectral resolution. We find several features that are indicative
of a bar in the kinematics of the stars, we see intermediate plateaus in the
velocity and the velocity dispersion, and correlation between the higher moment
$h3$ and the velocity. The gas kinematics is highly irregular, but is
consistent with non-triaxial streaming motions caused by a bar. The morphology
of the gas shows a spiral pattern, with seemingly lower inclination than the
stellar disk. We also look at the ionization mechanisms of the gas, which
happens mostly through shocks and not through starbursts.
