The morphology and structure of stellar populations in the Fornax dwarf
  spheroidal galaxy from Dark Energy Survey Data
  Using deep wide-field photometry three-year data (Y3) from the Dark Energy
Survey (DES), we present a panoramic study of the Fornax dwarf spheroidal
galaxy. The data presented here -- a small subset of the full survey --
uniformly covers a region of 25 square degrees centered on the galaxy to a
depth of g ~ 23.5. We use this data to study the structural properties of
Fornax, overall stellar population, and its member stars in different
evolutionary phases. We also search for possible signs of tidal disturbance.
Fornax is found to be significantly more spatially extended than what early
studies suggested. No statistically significant distortions or signs of tidal
disturbances were found down to a surface brightness limit of ~32.1
mag/arcsec^2. However, there are hints of shell-like features located ~30' -
40' from the center of Fornax that may be stellar debris from past merger
events. We also find that intermediate age and young main-sequence populations
show different orientation at the galaxy center and have many substructures.
The deep DES Y3 data allows us to characterize the age of those substructures
with great accuracy, both those previously known and those newly discovered in
this work, on the basis of their color-magnitude diagram morphology. We find
that the youngest overdensities are all found on the Eastern side of Fornax,
where the Fornax field population itself is slightly younger than in the West.
The high quality DES Y3 data reveals that Fornax has many rich structures, and
provides insights into its complex formation history.
