Neutron Star Structure and Neutron-Rich Matter

James M. Lattimer

Stony Brook University


The liquid-droplet equations of state of LPRL (Lattimer, Pethick, Ravenhall & Lamb) and LS (Lattimer & Swesty) are extended to incorporate better descriptions of the nuclear surface, the neutron skin of nuclei, and density-dependent effective nucleon masses, and are generalized to include both non-relativistic potential and relativistic field-theoretical nucleon-nucleon interactions. Laboratory measurements of nuclear masses, giant resonances, and neutron skin thicknesses provide some constraints to the models. Nevertheless, some basic parameters of the nucleon-nucleon interactions, conveniently expressed as the nuclear incompressibility, the nuclear symmetry energy (and its density dependence), and the specific heats of both bulk nuclear matter and the nuclear surface, are not yet adequately determined. Implications of uncertainties in these parameters for the structure of the crusts of neutron stars, including possible pasta phases, are discussed. Astronomical constraints from observations of neutron star thermal emissions and the timing of radio pulsars (i.e., mass, glitch, and moment of inertia measurements) are explored.


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