A 10 kpc stellar substructure at the edge of the Large Magellanic Cloud:
  perturbed outer disk or evidence for tidal stripping?
  We report the discovery of a substantial stellar overdensity in the periphery
of the Large Magellanic Cloud (LMC), found using public imaging from the first
year of the Dark Energy Survey. The structure appears to emanate from the edge
of the outer LMC disk at a radius $\approx 13.5$ degrees due north of its
centre, and stretches more than $10$ kpc towards the east. It is roughly $1.5$
kpc wide and has an integrated $V$-band luminosity of at least $M_V = -7.4$.
The stellar populations in the feature are indistinguishable from those in the
outer LMC disk. We attempt to quantify the geometry of the outer disk using
simple planar models, and find that only a disk with mild intrinsic ellipticity
can simultaneously explain the observed stellar density on the sky and the
azimuthal line-of-sight distance profile. We also see possible non-planar
behaviour in the outer disk that may reflect a warp and/or flare, as well as
deviations that resemble a ring-like structure between $\sim9-12$ degrees from
the LMC centre. Based on all these observations, we conclude that our remote,
stream-like feature is likely comprised of material that has been stripped from
the outskirts of the LMC disk, although we cannot rule out that it represents a
transient overdensity in the disk itself. We conduct a simple $N$-body
simulation to show that either type of structure could plausibly arise due to
the tidal force of the Milky Way; however we also recognize that a recent close
interaction between the LMC and the SMC may be the source of the stripping or
perturbation. Finally, we observe evidence for extremely diffuse LMC
populations extending to radii of $\sim 18.5$ kpc in the disk plane ($\approx
20$ degrees on the sky), corroborating previous spectroscopic detections at
comparable distances.
