Astrophysical Constraints on Dense Matter in Neutron Stars

Understand

Ever since the discovery of neutron stars it has been realized that they serve as probes of a physical regime that cannot be accessed in laboratories: strongly degenerate matter at several times nuclear saturation density.

• Existing nuclear theories diverge widely in their predictions about such matter.
• It could be that the matter is primarily nucleons, but it is also possible that exotic species such as hyperons, free quarks, condensates, or strange matter may dominate this regime.
• Astronomical observations of cold high-density matter are necessarily indirect, which means that we must rely on measurements of quantities such as the masses and radii of neutron stars and their surface effective temperatures as a function of age.