The Fornax 3D project: Thick disks in a cluster environment
  We used deep MUSE observations to perform a stellar-kinematic and population
analysis of FCC 153 and FCC 177, two edge-on S0 galaxies in the Fornax cluster.
The geometrical definition of the different structural components of these two
galaxies allows us to describe the nature of their thick disks. These are both
old, relatively metal poor and [Mg/Fe]-enhanced, and their star formation
history (SFH) reveals a minor younger component whose chemical properties
suggest its later accretion. Moreover, the outer regions of these geometrically
defined thick disks show higher values of metallicity and lower values of
[Mg/Fe]. These stars probably formed in the thin-disk region and they were
dynamically heated to form the flares present in these two galaxies. We propose
different formation scenarios for the three populations of these thick disks:
in-situ formation, accretion and disk heating. A clear distinction in age is
found between the metal poor and [Mg/Fe]-enhanced thick disks (old, $\sim
12-13$ Gyr), and the metal rich and less [Mg/Fe]-enhanced thin disks (young,
$\sim 4-5$ Gyr). These two galaxies show signs of relatively recent star
formation in their thin disks and nuclear regions. While the thin disks show
more continuous SFHs, the nuclei display a rather bursty SFH. These two
galaxies are located outside of the densest region of the Fornax cluster where
FCC 170 resides. This other edge-on S0 galaxy was studied by \citet{Pinna2019}.
We compare and discuss our results with this previous study. The differences
between these three galaxies, at different distances from the cluster center,
suggest that the environment can have a strong effect on the galaxy
evolutionary path.
