Insights into Neutron Star Matter: EoS Models and Observations

Abstract: The equation of state (EoS) for neutron stars is a crucial topic in astrophysics, nuclear physics, and quantum chromodynamics (QCD), influencing their structure, stability, and observable properties. This review classifies EoS models into hadronic matter, hybrid, and quark matter models, analyzing their assumptions, predictions, and constraints. While hadronic models characterize nucleonic matter, potentially including contributions from hyperons or mesons, hybrid models introduce phase transitions to quark matter, and quark models hypothesize the presence of deconfined quark matter cores or entirely quark-composed stars. By synthesizing results from recent theoretical and observational studies, this review aims to offer a comprehensive understanding of the methodologies used in constructing neutron star EoS, their implications, and future directions.