Dense Stellar Matter and Structure of Neutron Stars

After giving an overview of the history and idea of neutron stars, I shall discuss, in part one of my lectures, the physics of dense neutron star matter. In this connection concepts like chemical equilibrium and electric charge neutrality will be outlined, and the baryonic and mesonic degrees of freedom of neutron star matter as well as the transition of confined hadronic matter into quark matter at supernuclear densities are studied. Special emphasis is put onto the possible absolute stability of strange quark matter. Finally models for the equation of state of dense neutron star matter, which account for various physical possibilities concerning the unknown behavior of superdense neutron star matter, will be derived in the framework of relativistic nuclear field theory. Part two of my lectures deals with the construction of models of static as well as rapidly rotating neutron stars and an investigation of the cooling behavior of such objects. Both is performed in the framework of Einstein’s theory of general relativity. For this purpose the broad collection of models for the equation of state, derived in part one, will be used as an input. Finally, in part three a comparison of the theoretically computed neutron star properties (e.g., masses, radii, moments of inertia, red and blueshifts, limiting rotational periods, cooling behavior) with the body of observed data will be performed. From this conclusions about the interior structure of neutron stars – and thus the behavior of matter at extreme densities – will be drawn.