  The LIGO-Virgo collaboration ground-breaking detection of the binary
neutron-star merger event, GW170817, has expanded efforts to understand the
Equation of State (EoS) of nuclear matter. These measurements provide new
constraints on the overall pressure, but do not, by itself, elucidate its
microscopic origins, including the pressure arising from the symmetry energy,
that governs much of the internal structure of a neutron star. To correlate
microscopic constraints from nuclear measurements to the GW170817 constraints,
we calculate neutron star properties with more than 200 Skyrme energy density
functionals that describe properties of nuclei. Calculated neutron-star radii
(R) and the tidal deformabilities which show a strong correlation with pressure
at twice saturation density. By combining the neutron star EoS extracted from
the GW170817 event and the EoS of symmetric matter from nucleus-nucleus
collision experiments, we extract the density dependence of the symmetry
pressure from 1.2 to 4.5 times saturation density. While the uncertainties in
the symmetry pressure are large, they can be reduced with new experimental and
astrophysical results.
