Constraints on the Field Star IMF from Resolved Stellar Populations
  based Star Formation Histories
  Using HST/ACS observations of resolved stellar populations in nearby
galaxies, I explore the constraints one can place on the field star IMF from
star formation histories (SFHs) derived from synthetic color-magnitude diagram
(CMD) fitting. In particular, I show how reasonable variations in the slope of
the IMF, relative to a Salpeter slope, lead to only minor changes in the SFHs.
This shows that CMD-SFH fitting parameter space has a broad minimum with
respect to IMF variations and implies that CMD based SFHs can only provide weak
explicit constraints on the stellar IMF. However, observations of resolved
stellar populations in dwarf galaxies can be used to tandem with other methods
to search for variations in the upper IMF.
