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Low Surface Brightness Imaging of the Magellanic System: Imprints of Tidal Interactions between the Clouds in the Stellar Periphery
We present deep optical images of the Large and Small Magellanic Clouds (LMC
and SMC) using a low cost telephoto lens with a wide field of view to explore
stellar substructure in the outskirts of the stellar disk of the LMC (r < 10
degrees from the center). These data have higher resolution than existing star
count maps, and highlight the existence of stellar arcs and multiple spiral
arms in the northern periphery, with no comparable counterparts in the South.
We compare these data to detailed simulations of the LMC disk outskirts,
following interactions with its low mass companion, the SMC. We consider
interaction in isolation and with the inclusion of the Milky Way tidal field.
The simulations are used to assess the origin of the northern structures,
including also the low density stellar arc recently identified in the DES data
by Mackey et al. 2015 at ~ 15 degrees. We conclude that repeated close
interactions with the SMC are primarily responsible for the asymmetric stellar
structures seen in the periphery of the LMC. The orientation and density of
these arcs can be used to constrain the LMC's interaction history with and
impact parameter of the SMC. More generally, we find that such asymmetric
structures should be ubiquitous about pairs of dwarfs and can persist for 1-2
Gyr even after the secondary merges entirely with the primary. As such, the
lack of a companion around a Magellanic Irregular does not disprove the
hypothesis that their asymmetric structures are driven by dwarf-dwarf
interactions.Comment: Submitted to ApJ. Comments are welcome
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