1202.0358 (Kenji Bekki)
Kenji Bekki
We investigate how the Large Magellanic Cloud (LMC) influences the evolution
of the Galaxy after the LMC enters into the virial radius of the dark matter
halo of the Galaxy for the first time. Both the Galaxy and the LMC are modeled
as N-body particles in our models so that the dynamical influences of the LMC
on the Galaxy can be investigated in a fully self-consistent manner.
Furthermore, the orbital parameters for the LMC are carefully chosen such that
the present location of the LMC in the Galaxy can be rather precisely
reproduced in our simulations. We particularly investigate the influences of
the LMC on the precession rate, the outer stellar and gaseous structures, and
the star formation history of the Galaxy. Our principals results are summarized
as follows. The LMC-Galaxy dynamical interaction can cause "pole shift" (or
irregular precession/nutation) of the Galaxy and the typical rate of pole shift
(dot {\theta}_{d}) is ~2 degree Gyr^{-1} corresponding to ~ 7 muas yr^{-1}. The
LMC-Galaxy interaction induces the formation of the outer warp structures of
the Galaxy, which thus confirms the results of previous numerical simulations
on the formation of the Galactic warp. The LMC-Galaxy interaction also induces
the formation of outer (R>20 kpc) spiral arms and increases the vertical
velocity dispersion of the outer disk significantly. The mean star formation
rate of the Galaxy for the last several Gyrs can be hardly influenced by the
LMC's tidal force. The age and metallicity distribution of stars in the
solar-neighborhood (7 kpc < R < 10 kpc) for the last several Gyr can be only
slightly changed by the past LMC-Galaxy interaction. Based on these results, we
discuss how the possible ongoing Galactic pole shift with 10 muas yr^{-1} can
be detected by future observational studies by GAIA.
View original:
http://arxiv.org/abs/1202.0358
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