STROBE-X: Probing Neutron Star Structure and the Dense Matter Equation of State

The poorly understood behavior of matter at ultra-high density, high proton/neutron number asymmetry, and low temperature present one of the major outstanding problems in physics. Since matter in this extreme state is known to only exist stably in the cores of neutron stars, astrophysical observations of neutron stars can provide key insight into the properties of matter in a region of the quantum chromodynamics phase space that is otherwise inaccessible. The proposed STROBE-X probe-class mission, with its large collecting area, superb spectral and temporal resolution, and rapid slew capabilities, will enable multiple complementary approaches based on X-ray pulse profile modeling and spectroscopy that could produce definitive definitive empirical constraints on the true nature of the densest matter in the Universe.