Astrophysical Studies of Quark Deconfinement

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This project concerns the theoretical exploration of the properties of strongly interacting matter at ultra-high densities (10 to 20 times denser than atomic nuclei) and temperatures (several hundred billion degrees). It is generally accepted by the scientific community that the universe was filled with super-dense matter shortly after the Big Bang. Super-dense matter continues to be created in the final stages of catastrophic stellar events, such as core-collapse supernovae and gamma-ray bursts, and it may be present deep inside the cores of collapsed stars, known as neutron stars. Neutron stars are typically about 20 kilometers across and spin rapidly, often making many hundred of rotations per second. A thimble full of neutron star matter would have a mass of one billion tons! At such extraordinary conditions atoms themselves collapse, and atomic nuclei are squeezed so tightly together that new fundamental particles are generated and novel states of matter are created. This makes neutron stars, and the catastrophic stellar events creating them, into excellent astrophysical laboratories for a wide range of physical studies, which are addressed in this project. Theoretical predictions concerning the equation of state of matter under these extreme conditions can be used to compare the results of simulations with observational data accumulating rapidly from both orbiting and ground based observatories spanning the radiation spectrum from X-rays to radio wavelengths.This project focuses on the role of quark deconfinement for (proto) neutron stars and core-collapse supernova events, using a state-of-the-art (non-local 3-flavor Polyakov-Nambu-Jona-Lasinio, n3PNJL) model for the description of quark matter. The n3PNJL model accounts for the dynamical breaking of chiral symmetry and mimics quark confinement via the Polyakov loop potential. In recent years, the Nambu-Jona-Lasinio model has become the workhorse for various studies in theoretical nuclear physics, as it provides a very versatile and numerically treatable approach to the theory of the strong interaction (quantum chromodynamics, QCD). This research will consists of five intertwined activities concerning (1) the equation of state of cold quark-hybrid matter; (2) color superconductivity treated in the framework of the n3PNJL model; (3) quark deconfinement in (proto) neutron stars; (4) the properties of a quark-hadron Coulomb lattice that may exist in the cores of neutron stars; and (5) the role of quark deconfinement for core-collapse supernovae. The best available data from heavy ion collisions and neutron star observations will be used to impose the strongest possible constraints on the equation of state that will be developed in the framework of this research project. The equations of state will be made available to the wider nuclear and astrophysics community to explore the birth, structure and evolution of (proto) neutron stars and the events which create them.