Modelling Hybrid Stars in Quark-Hadron Approaches

The density in the core of neutron stars can reach values of about 5 to 10 times nuclear matter saturation density. It is, therefore, a natural assumption that hadrons may have dissolved into quarks under such conditions, forming a hybrid star. This star will have an outer region of hadronic matter and a core of quark matter or even a mixed state of hadrons and quarks. In order to investigate such phases, we discuss different model approaches that can be used in the study of compact stars as well as being applicable to a wider range of temperatures and densities. One major model ingredient, the role of quark interactions in the stability of massive hybrid stars is discussed. In this context, possible conflicts with lattice QCD simulations are investigated.Comment: Contribution to the EPJA Topical Issue on "Exotic Matter in Neutron Stars

Constraining strangeness in dense matter with GW170817

Particles with strangeness content are predicted to populate dense matter, modifying the equation of state of matter inside neutron stars as well as their structure and evolution. In this work, we show how the modeling of strangeness content in dense matter affects the properties of isolated neutrons stars and the tidal deformation in binary systems. For describing nucleonic and hyperonic stars we use the many-body forces model (MBF) at zero temperature, including the $\phi$ mesons for the description of repulsive hyperon-hyperon interactions. Hybrid stars are modeled using the MIT Bag Model with vector interaction (vMIT) in both Gibbs and Maxwell constructions, for different values of bag constant and vector interaction couplings. A parametrization with a Maxwell construction, which gives rise to third family of compact stars (twin stars), is also investigated. We calculate the tidal contribution that adds to the post-Newtonian point-particle corrections, the associated love number for sequences of stars of different composition (nucleonic, hyperonic, hybrid and twin stars), and determine signatures of the phase transition on the gravitational waves in the accumulated phase correction during the inspirals among different scenarios for binary systems. On the light of the recent results from GW170817 and the implications for the radius of $\sim1.4\,\mathrm{M_{\odot}}$ stars, our results show that hybrid stars can only exist if a phase transition takes place at low densities close to saturation

Space processing of chalcogenide glass

A program was conducted to develop the technique of space processing for chalcogenide glass, and to define the process and equipment necessary. In the course of this program, successful long term levitation of objects in a 1-g environment was achieved. Glass beads 4 mm diameter were containerless melted and fused together

Deconfinement to Quark Matter in Neutron Stars - The Influence of Strong Magnetic Fields

We use an extended version of the hadronic SU(3) non-linear realization of the sigma model that also includes quarks to study hybrid stars. Within this approach, the degrees of freedom change naturally as the temperature/density increases. Different prescriptions of charge neutrality, local and global, are tested and the influence of strong magnetic fields and the anomalous magnetic moment on the particle population is discussed.Comment: To appear in the proceedings of conference XII HADRON PHYSICS April, 22-27, 2012, Bento Goncalves, Wineyards Valley Region, Rio Grande do Sul, Brazil Revised version with corrections made to the text in page