Abstract
Neutron star matter spans a wide range of densities, from that of nuclei at the surface to exceeding several times normal nuclear matter density in the core. While terrestrial experiments, such as nuclear or heavy-ion collision experiments, provide clues about the behaviour of dense nuclear matter, one must resort to theoretical models of neutron star matter to extrapolate to higher density and finite neutron/proton asymmetry relevant for neutron stars. In this work, we explore the parameter space within the framework of the Relativistic Mean Field model allowed by present uncertainties compatible with state-of-the-art experimental data. We apply a cut-off filter scheme to constrain the parameter space using multi-physics constraints at different density regimes: chiral effective field theory, nuclear and heavy-ion collision data as well as multi-messenger astrophysical observations of neutron stars. Using the results of the study, we investigate possible correlations between nuclear and astrophysical observables.
Highlights
Reached in heavy-ion collisions at relativistic energies
FOPI experiment Using the data on elliptic flow in Au + Au collisions between 0.4 and 1.5A GeV by FOPI collaboration [13], one can obtain constraints for the Equation of State (EoS) of compressed symmetric nuclear matter (SNM) using the transport code Isospin Quantum Molecular Dynamics (IQMD) by introducing an observable describing the evolution of the size of the elliptic flow as a function of rapidity
We imposed filters from physical constraints such as χ EFT data and recent Neutron stars (NS) astrophysical observations of mass, radius and tidal deformability to restrict the choice of parameters
Summary
The behaviour of matter can be represented in terms of its pressure-density relationship, known as the Equation of State (EoS) [4,5,9]. Since the pioneering works by Steiner et al [68], there have been many attempts to impose constraints on the EoS by using multi-messenger observations of neutron stars using a statistical Bayesian scheme [69–75] The idea of this scheme is to match the low density EOS constrained by theoretical and experimental nuclear physics with parametrized high density EOSs satisfying gravitational wave and electromagnetic data [76–80]. We apply a simple cut-off filter scheme to constrain the parameter space using a combination of current best-known physical constraints at different density regimes: theoretical (chiral effective field theory) at low densities, experimental (nuclear and heavy-ion collision) at intermediate densities and multi-messenger (multi-wavelength electromagnetic as well as GW) astrophysical data at high densities to restrict the parameter space of the nuclear model.
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