2014/04/30 by Sarmistha Banik, Matthias Hempel, Debades Bandyopadhyay · 1 citation
Physics and Astronomy · #astro-ph.HE #astro-ph.SR #nucl-th
paper · pdf · doi:10.1088/0067-0049/214/2/22
published as Astrophys. J. Suppl. 214 (2014) 22 · 39 pages, 9 figures, 11 tables; matches published version, only minor additions and editorial changes
arxiv created 2014/08/25 · arxiv updated 2015/03/03
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 from Typel et al. (2010) for nucleons. Furthermore, light and heavy nuclei along with the 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 wide range of density (10-12 to ∼ 1 fm-3), temperature (0.1 to 158.48 MeV), and proton fraction (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 high densities. The cold, β-equilibrated EoS (with the crust included self-consistently) results in a 2.1 M\odot maximum mass neutron star for the npΛϕ case, whereas that for the npΛ case is 1.95 M\odot. The npΛϕ EoS represents the first supernova EoS table involving hyperons that is directly compatible with the recently measured 2 M\odot neutron stars.