Abstract
A wealth of recent studies have shown that the LMC is likely massive, with a
halo mass $>10^11 M_ødot$. One consequence of having such a nearby and
massive neighbour is that the inner Milky Way is expected to be accelerated
with respect to our Galaxy's outskirts (beyond $30$ kpc). In this work we
compile a sample of $500$ stars with radial velocities in the distant
stellar halo, $r_GC> 50$ kpc, to test this hypothesis. These stars span a
large fraction of the sky and thus give a global view of the stellar halo. We
find that stars in the Southern hemisphere are on average blueshifted, while
stars in the North are redshifted, consistent with the expected, mostly
downwards acceleration of the inner halo due to the LMC. We compare these
results with simulations and find the signal is consistent with the infall of a
$1.5\times10^11 M_ødot$ LMC. We cross-match our stellar sample with
Gaia DR2 and find that the mean proper motions are not yet precise
enough to discern the LMC's effect. Our results show that the outer Milky Way
is significantly out of equilibrium and that the LMC has a substantial effect
on our Galaxy.
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