Updates of the nuclear equation of state for core-collapse supernovae and neutron stars: effects of 3-body forces, QCD, and magnetic fields

G J Mathews,J Hidaka,N Q Lan,M Meixner,T Kajino,M-K Cheoun,T Maruyama,I-S Suh,J P Olson,C-Y Ryu

doi:10.1088/1742-6596/445/1/012023

Abstract

We summarize several new developments in the nuclear equation of state for supernova simulations and neutron stars. We discuss an updated and improved Notre-Dame-Livermore Equation of State (NDL EoS) for use in supernovae simulations. This Eos contains many updates. Among them are the effects of 3- body nuclear forces at high densities and the possible transition to a QCD chiral and/or super-conducting color phase at densities. We also consider the neutron star equation of state and neutrino transport in the presence of strong magnetic fields. We study a new quantum hadrodynamic (QHD) equation of state for neutron stars (with and without hyperons) in the presence of strong magnetic fields. The parameters are constrained by deduced masses and radii. The calculated adiabatic index for these magnetized neutron stars exhibit rapid changes with density. This may provide a mechanism for star-quakes and flares in magnetars. We also investigate the strong magnetic field effects on the moments of inertia and spin down of neutron stars. The change of the moment of inertia associated with emitted magnetic flares is shown to match well with observed glitches in some magnetars. We also discuss a perturbative calculation of neutrino scattering and absorption in hot and dense hyperonic neutron-star matter in the presence of a strong magnetic field. The absorption cross-sections show a remarkable angular dependence in that the neutrino absorption strength is reduced in a direction parallel to the magnetic field and enhanced in the opposite direction. The pulsar kick velocities associated with this asymmetry comparable to observed pulsar velocities and may affect the early spin down rate of proto-neutron star magnetars with a toroidal field configuration.

Highlights

To describe the structure and hydrodynamics of compact matter; an equation of state (EoS) is needed to relate the physics of the state variables [1]
The former utilizes a non relativistic parameterization of nuclear interactions in which nuclei are treated as a compressible liquid drop including surface effects. The latter is based upon a Relativistic Mean Field (RMF) model using the TM1 parameter set in which nuclei are calculated in a Thomas-Fermi approximation
Magnetic Fields and The Eos We have considered the neutron star equation of state and neutrino transport in the presence of strong magnetic fields [25]-[30]

Summary

Introduction

To describe the structure and hydrodynamics of compact matter; an equation of state (EoS) is needed to relate the physics of the state variables [1]. Among the new features in the NDL EoS is that high density phase of the EoS is treated with a parameterized Skyrme energy density functional that utilizes a modified zero range 3-body interaction. For many Skyrme models the symmetry energy either saturates at high densities, or in the worst case becomes negative.

Results

Conclusion