Quark Matter and its Role in the Evolution of Proton-Neutron Stars to Neutron Stars

San Diego State University Foundation, San Diego CA

Investigators

Abstract

Galaxies are filled with hundreds of millions of compact stellar objects known as neutron stars. Neutron stars are more massive than our Sun, but are typically only about 20 kilometers across. A thimble full of neutron star matter thus has a mass of one billion tons. At such extraordinary conditions, atomic nuclei collapse and neutrons and protons are squeezed so tightly together that even their building blocks (quarks) may be released. The aim of this project is to study the role of quarks for newly formed neutron stars and to identify possible signatures in astrophysical observables. Graduate and undergraduate students will be trained in areas of physics that are richly interdisciplinary and enrich their educational experience beyond what they learn in the classroom. Students from local middle and high schools will benefit from the PI's research in the form of public lectures and multimedia presentations. This research will support the physics program at state-of-the-art astrophysical instruments, such as FAST, skA, ATHENA, and NICER, that promise the discovery of tens of thousands of new neutron stars at different stages of their evolution. The principal aim of this proposal is to study quark matter under conditions characteristic to proto-neutron stars, using the non-local 3-flavor Polyakov-Nambu-Jona-Lasinio (n3PNJL) model to describe hot and dense quark matter, and to explore the role of quark matter in the evolution of proto-neutron stars to neutron stars. The n3PNJL model is an effective model of quantum chromodynamics that allows for a state-of-the-art modeling of quark matter. The model accounts for the dynamical breaking of chiral symmetry and mimics quark confinement via the Polyakov-loop potential. It provides a versatile and numerically-treatable approach to quantum chromodynamics. The best available data from heavy-ion collisions and neutron star observations will be used to constrain the equation of state of (proto-) neutron star matter, which will be computed and made publicly available online at CompOSE and StellarCollapse. Already existing, fully general relativistic numerical 2D rotation and 2D cooling codes will be used to study the rotational evolution of hot proto-neutron stars to cold catalyzed neutron stars self-consistently. Both uniformly-rotating as well as differentially-rotating systems will be considered and their role as possible sources of gravitational radiation explored.