The equation of state and composition of hot, dense matter in core-collapse supernovae

¹ Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Strasse 1, Postfach 1523, 85740 Garching, Germany
e-mail seb@mpa-garching.mpg.de
² Institute for Theoretical and Experimental Physics, B. Cheremushkinskaya St. 25, 117218 Moscow, Russia
³ IPMU, University of Tokyo 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8568, Japan
⁴ Computer Science Department, Technion-Israel Institute of Technology, 32000 Haifa, Israel
⁵ Numazu College of Technology, Ooka 3600, Numazu, Shizuoka 410-8501, Japan
⁶ Theory Center, High Energy Accelerator Research Organization (KEK), Oho 1-1, Tsukuba, Ibaraki 305-0801, Japan

Received: 24 April 2009
Accepted: 16 August 2011

Abstract

The equation of state (EOS) and composition of matter are calculated for conditions typical for pre-collapse and early collapse stages in core-collapse supernovae. The composition is evaluated under the assumption of nuclear statistical equilibrium, when the matter is considered as an “almost” ideal gas with corrections owing to thermal excitations of nuclei, to free nucleon degeneracy, and to Coulomb and surface-energy corrections. The account of these corrections allows us to obtain the composition for densities that are slightly below the nuclear matter density. Through comparisons with the EOS developed by Shen et al., which is used in most of recent supernova simulations, we examine the differences of our EOS in the multi-composition with the EOS in the approximation of one representative nucleus. We find that widely distributed compositions in the nuclear chart are different because of the different mass formulae we used, while the thermodynamical quantities are quite close to those in Shen’s EOS.