Speaker
Description
The nature of the equation of state (EOS) of neutron stars is an open research problem. The high baryonic density and isospin asymmetry that characterize this system hinder first principle calculations of the EOS, its particle composition and in-medium particle interactions. Therefore, at the moment there is no consensus on the presence of quark matter in neutron star cores, or on the nuclear pairing model to describe neutron triplet superfluidity and proton superconductivity in the system. However, using cooling data from transiently-accreting neutron stars, one has obtained the first unambiguous signature of the presence of fast neutrino-cooling processes in the core of a star for the MXB 1659-29 source. Neutrino emissivity is directly related to neutron star’s core composition; thus this data can set important constraints on the EOS.
In this talk, we present the results of a study of a set of realistic relativistic mean field (RMF) EOS reproducing MXB 1659-29 luminosity and making predictions for its mass and nuclear pairing models. We also investigate whether quark matter can be present in this source and for which densities, for each EOS. Finally, we calculate the core heat capacities for all scenarios and check whether long-term measurements of temperature variation combined with inferred luminosity for a star can set them apart and potentially provide information on the star’s core composition. This is an important step towards an eventual universal equation of state for neutron stars and, therefore, towards a better understanding of the phase diagram of asymmetric matter at high densities.
