Existence of exotic matter in neutron star inner cores

Ascertain whether exotic degrees of freedom—hyperons (Λ, Σ, Ξ) or deconfined quarks (u, d, s)—are present in the inner core of neutron stars at high densities, beyond the conventional npeμ composition assumed in the outer core.

Background

The authors construct neutron star models using a conventional npeμ composition for the core and classical crust EoSs, explicitly excluding exotic phases in the inner core.

They state that the presence of hyperonic or quark matter in the deepest region of neutron stars remains uncertain and identify this as an open question in nuclear astrophysics, motivating their choice to omit such phases in the present work.