Symmetry energy impact in simulations of core-collapse supernovae

Abstract

Abstract. We present a review of a broad selection of nuclear matter equations of state (EOSs) applicable in core-collapse supernova studies. The large variety of nuclear matter properties, such as the symmetry energy, which are covered by these EOSs leads to distinct outcomes in supernova simulations. Many of the currently used EOS models can be ruled out by nuclear experiments, nuclear many-body calculations, and observations of neutron stars. In particular the two classical supernova EOS describe neutron matter poorly. Nevertheless, we explore their impact in supernova simulations since they are commonly used in astrophysics. They serve as extremely soft and stiff representative nuclear models. The corresponding supernova simulations represent two extreme cases, e.g., with respect to the protoneutron star (PNS) compactness and shock evolution. Moreover, in multi-dimensional supernova simulations EOS differences have a strong effect on the explosion dynamics. Because of the extreme behaviors of the classical supernova EOSs we also include DD2, a relativistic mean field EOS with density-dependent couplings, which is in satisfactory agreement with many current nuclear and observational constraints. This is the first time that DD2 is applied to supernova simulations and compared with the classical supernova EOS. We find that the overall behaviour of the latter EOS in supernova simulations lies in between the two extreme classical EOSs. As pointed out in previous studies, we confirm the impact of the symmetry energy on the electron fraction. Furthermore, we find that the symmetry energy becomes less important during the post-bounce evolution, where conversely the symmetric part of the EOS becomes increasingly dominating, which is related to the high temperatures obtained. Moreover, we study the possible impact of quark matter at high densities and light nuclear clusters at low and intermediate densities.

Constraining supernova equations of state with equilibrium constants from heavy-ion collisions

“…[42], which is based on the HS model, but employs a nucleon-nucleon interaction different from HS(DD2). We have selected this model as another interesting case from the various HS models available in the literature [5], because its nuclear matter properties are in agreement with various experimental and theoretical constraints, as are those for the HS(DD2) EOS. However, this model is constructed such that certain radius measurements of neutron stars were reproduced.…”

“…It has been shown in several works [1][2][3][4][5], that these conditions are realized in nature in core-collapse supernovae (SN). There, nuclear clusters appear abundantly in the shock heated matter and in the envelope of the newly born proto-neutron star.…”

Symmetry Parameter Constraints from a Lower Bound on Neutron-matter Energy

“…It provides the pressure of neutron-star matter, which is nearly pure neutron matter (PNM) near the saturation density n 0 ;0.16 fm −3 , and largely determines neutron-star radii (Lattimer & Prakash 2001) and therefore properties of their crusts, moments of inertia, tidal polarizabilities, and binding energies (Lattimer & Prakash 2007). The symmetry energy is also important in calculations of the r-process (Mumpower et al 2016), supernovae (Fischer et al 2014), and neutron-star mergers (Bauswein et al 2016). Terrestrial experiments measuring nuclear masses, dipole resonances, and neutronskin thicknesses can constrain the symmetry energy (Lattimer & Lim 2013), as can experiments using normal and radioactive nuclear beams (Oertel et al 2017).…”

Quasi-Periodic Gravitational-Wave Emission due to the SASI Motion

“…By considering, such as, their symmetry energy at nuclear saturation density and the radius of cold NS, SFHx is the softest EOS followed in order by DD2, and TM1 [8]. Our 3D-GR models are named as DD2, TM1 and SFHx, which simply reflects the EoS used.…”