Nuclear Astrophysics: Unknown Knowns
The advent of precise measurements of neutron star properties has led to an explosion in "nuclear astrophysics": studying the properties of high-density matter using astrophysical phenomena. Remarkably, constraints provided by nuclear theory and experiment and high-energy astrophysical observations are now competitive (and often complementary) in constraining the equation of state (EoS) of matter at supernuclear densities. On the astrophysical side, data have provided a clearer picture how these constraints are affected by the choice of modeling the EoS. Specifically, the nuclear EoS in astrophysical analyses is usually modeled phenomenologically, and often using ad hoc assumptions. I will discuss why these ad hoc assumptions will likely cause problems, considering the deluge of coming neutron-star measurements, by comparing these approaches to a data-driven, "nonparametric", model.