LAUSR

We investigate the properties of high density compact objects in a vector type theory, inspired by Einstein’s 1919 theory of elementary particles, in which Einstein assumed that elementary particles are held together by gravitational as well as electromagnetic type forces. From a modern perspective, Einstein’s theory can be interpreted as a vector type model, with the gravitational action constructed as a linear combination of the Ricci scalar, of the trace of the matter energy-momentum tensor, and of a massive self-interacting vector type field. To obtain the properties of stellar models we consider the field equations for a static, spherically symmetric system, and we investigate numerically their solutions for different equations of state of quark and neutron matter, by assuming that the self-interaction potential of the vector field either vanishes, or is quadratic in the vector field potential. We consider quark stars described by the MIT bag model equation of state, and in the Color Flavor Locked (CFL) phase, as well as compact stars consisting of a Bose-Einstein Condensate of neutron matter, with neutrons forming Cooper pairs. Constant density stars, representing a generalization of the Interior Schwarzschild solution of general relativity, are also analyzed. As an example of stars described by equations of state obtained by using effective nuclear interactions of the Skyrme type we consider the Douchin-Haensel (SLy) equation of state. The numerical solutions are explicitly obtained in both standard general relativity, and the Einstein dark energy model, and an in depth comparison between the astrophysical predictions of these two theories are performed. As a general conclusion of our study we find that for all the considered equations of state a much larger variety of stellar structures can be obtained in the Einstein dark energy model, including classes of stars that are more massive than their general relativistic counterparts. As a concrete applications of our results we suggest that compact objects with masses of the order of 2 . 5 M ⊙ , associated, for example, with the GW 190814 gravitational wave event, could be in fact quark or neutron stars, described by the Einstein dark energy model.