NEW HYPERON EQUATIONS OF STATE FOR SUPERNOVAE AND NEUTRON STARS IN DENSITY-DEPENDENT HADRON FIELD THEORY

By S. Banik, M. Hempel, D. Bandyopadhyay. 2014

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We develop new hyperon equation of state (EoS) tables for core-collapse supernova simulations and neutron stars. These EoS tables are based on a density-dependent relativistic hadron field theory where baryon–baryon interaction is mediated by mesons, using the parameter set DD2 for nucleons. Furthermore, light and heavy nuclei along with interacting nucleons are treated in the nuclear statistical equilibrium model of Hempel and Schaffner-Bielich which includes excluded volume effects. Of all possible hyperons, we consider only the contribution of Λs. We have developed two variants of hyperonic EoS tables: in the npΛϕ case the repulsive hyperon–hyperon interaction mediated by the strange ϕ meson is taken into account, and in the npΛ case it is not. The EoS tables for the two cases encompass a wide range of densities (10−12 to ∼1 fm−3), temperatures (0.1 to 158.48 MeV), and proton fractions (0.01 to 0.60). The effects of Λ hyperons on thermodynamic quantities such as free energy per baryon, pressure, or entropy per baryon are investigated and found to be significant at higher densities. The cold, β-equilibrated EoS (with the crust included self-consistently) results in a 2.1 M☉ maximum mass neutron star for the npΛϕ case, whereas that for the npΛ case is 1.95 M☉. The npΛϕ EoS represents the first supernova EoS table involving hyperons that is directly compatible with the recently measured 2 M☉ neutron stars.

Subfields: Astronomy and Astrophysics, Geophysics

View Paper: https://www.semanticscholar.org/paper/acc6c76cda09a97483fc564c7a8bab7b0d4294a6

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Citations in the corpus

GW170817: Joint Constraint on the Neutron Star Equation of State from Multimessenger Observations (2017, methodology): “Bauswein et al. (2017) combined this observation with empirical relations between NS radii and the threshold mass for prompt collapse, which was previously found by means of simulations with an approximate treatment of general relativity (GR; Bauswein et al. 2013a), to tentatively rule out EOSs pred”
Mass Ejection from the Remnant of a Binary Neutron Star Merger: Viscous-radiation Hydrodynamics Study (2017, methodology): “For the neutron star EOS, we employ a tabulated EOS referred to as DD2 (Banik et al. 2014).”
Using Gravitational-wave Observations and Quasi-universal Relations to Constrain the Maximum Mass of Neutron Stars (2017, background): “…a popular EOS routinely employed in numerical-relativity calculations such as the DD2 EOS (Typel et al. 2010), violates the constraint (7) since it has MTOV = 2.419M ; at the same time, EOSs with hyperons, e.g., BHBΛΦ (Banik et al. 2014) and DD2Y (Marques et al. 2017), have maximum masses .”
The Gravitational Wave Signal from Core-collapse Supernovae (2018, methodology): “In our models, we use three different equations of state (EOS), namely, the SFHo EOS (Steiner et al. 2013), the Lattimer-Swesty EOS with nuclear incompressibility parameter 220 MeV (Lattimer & Swesty 1991), and the DD2 EOS (Fischer et al. 2014; Banik et al. 2014).”
Binary Neutron Star Mergers: Mass Ejection, Electromagnetic Counterparts, and Nucleosynthesis (2018, methodology): “The BHBΛf EOS uses the same nucleon interactions as the DD2 EOS, but also includes interacting Λ hyperons that can be produced at high density and soften the EOS.”