Core-crust transition pressure for relativistic slowly rotating neutron stars

We study the influence of core-\textit{crust} transition pressure changes on the general dynamical properties of neutron star configurations. First we study the matching conditions in core-\textit{crust} transition pressure region, where phase transitions in the equation of state causes energy density jumps. Then using a surface \textit{crust} approximation, we can construct configurations where the matter is described by the equation of state of the core of the star and the core-\textit{crust} transition pressure. We will consider neutron stars in the slow rotation limit, considering perturbation theory up to second order in the angular velocity so that the deformation of the star is also taken into account. The junction determines the parameters of the star such as total mass, angular and quadrupolar momentum.Comment: 4 pages, 1 figur

New model of relativistic slowly rotating neutron stars with surface layer \textit{crust}: application to giant \textit{glitches} of Vela Pulsar

Introducing a surface layer of matter on the edge of a neutron star in slow rigid rotation, we analyze, from an intrinsic point of view, the junction conditions that must be satisfied between the interior and exterior solutions of the Einstein equations. In our model the core-\textit{crust} transition pressure arise as an essential parameter in the description of a configuration. As an application of this formalism, we describe giant \textit{glitches} of the Vela pulsar as a result of variations in the transition pressure, finding that these small changes are compatible with the expected temperature variations of the inner crust during \textit{glitch} time.Comment: 4 pages, 2 figures, to appear in Proceedings of Spanish Relativity Meeting 2010 (ERE 2010) held in Granada, Spai

A wide family of singularity-free cosmological models

In this paper a family of non-singular cylindrical perfect fluid cosmologies is derived. The equation of state corresponds to a stiff fluid. The family depends on two independent functions under very simple conditions. A sufficient condition for geodesic completeness is provided.Comment: 7 pages, RevTeX