CERN/FP/109316/2009 - Asymmetric nuclear matter: from the lab to neutron stars

Nuclear astrophysics is a blooming area where compact stars play an essential role and which requires the contribution of different areas of physics, namely, nuclear and particle physics, astrophysics, gravitational and computational physics. The team of the present project is integrated in a RNP (Reseach Network Program) of the European Science Foundation, called "The New Physics of Compact Stars", which aims at linking the best European scientists on the above fields, to reach a better understanding of the physics of compact stars. The IR of the project is member of the steering committee in representation of Portugal. The topics proposed in the present project are hot topics in the field and will try to address open questions like: -. How to constrain the equation of state of nuclear matter from compact star properties or from laboratory measurements such as the ones planned for the next-generation of exotic radioactive beam facilities at the CSR/China, FAIR/Germany, RIKEN/Japan, SPIRAL2/GANIL in France, and the planned Facility for Rare Isotope Beams (FRIB) in the USA, where the high density behavior of symmetry energy can be studied experimentally in the near future ? -. Is it possible that most of the cold compact stars are quark stars? -. How are the stellar matter properties affected by strong magnetic fields? The collaborators proposed in the project belong either to the "The New Physics of Compact Stars" network (we expect to strengthen the team in the compact star community) or to the team of physicists in Brasil with whom we have kept strong collaboration during the last years. The research lines of the present project are devoted to the theoretical description of several aspects of hadron physics, nuclear physics and astrophysics with a special focus on the aspects related with compact stars physics. We will study the instabilities on stellar matter at subsaturation densities within a Self Consistent Green´s function method and the dynamical instabilities using Brueckner-Hartree-Fock approach and compare these results with previous ones obtained from phenomenological non-relativistic interactions and relativistic mean-field nuclear models. We will investigate how does the spinodal surface depend on the symmetry energy and its density derivatives, i.e. the slope L and the curvature K_sym, in order to obtain constraints on the equation of state of asymmetric nuclear matter. We will continue our work on the pasta phase and calculate the pasta phase using the more realistic density dependent relativistic models in a Thomas Fermi approach at finite temperature and a comparison of the crust-core transition density obtained within different approaches will be done, analyse the effect of neutrino trapping on the extension of the pasta phase and compare the results from the pasta calculation with the non-homogeneous phase obtained from dynamical spinodal calculation. We will study the effect of strong magnetic fields on the extension and geometry of the pasta phase and on the thermodynamical properties of stellar matter at the crust of a compact star as well as its spin wave excitations in the presence of magnetic fields. Finally we will establish under which conditions a newborn hadronic star could survive the early stages of its evolution without "decaying" to a quark star. The team has expertise on both relativistic and non-relativistic phenomenological nuclear models; nuclear models built from first principles like Brueckner Hartree-Fock formalism; hadronic and quark models and thermodynamical and dynamical description of nuclear matter. We will have the possibility of comparing different approaches and conclude about the robustness of the results. New expertise will be developped on the Self Consistent Green´ Functions Method, finite temperature Thomas Fermi calculation for non-homogeneous matter. Although the project is quite challenging on the amount of results programmed we expect that most of the problems will have a fast answer due to the knowledge and the experience of the group, and we count also with the contribution of our collaborators

Status: Concluded

Starting date: 1-1-2010

End date: 28-2-2011

Financing: 25keuro Euros

Financing entity: FCT

Person*month: 0

Group person*month: 0