Speaker
Description
Recent observations from X-ray telescopes, radio timing of pulsars, and gravitational wave observations, have provided several constraints on the masses and radii of neutron stars. Major efforts are being devoted to inferring the underlying pressure-energy density relation, often called the equation of state (EOS), of dense matter. This involves the inversion of the TOV relations of neutron star structure. The close correspondence between neutron star matter pressure near the saturation density and the radii of typical neutron stars is one example of a semi-universal relation relating the M-R relation to the EOS, as is the Yagi-Yunes I-Love relation connecting the moments of inertia and the tidal deformability of neutron stars. These relations are valid for all or nearly all equations of state to high precision. It is demonstrated that the inference of the EOS from mass and radius observations is sensitive to the inversion method. A new analytic method of inverting an individual M-R relation to its underlying EOS to within about 0.5\% might permit more accurate inferences. It is also shown how an upper bound to the neutron matter energy, in analogy to the lower bound stemming from the Unitary Gas Conjecture, could further restrict EOS properties.
