Composition of the Innermost Core-Collapse Supernova Ejecta

By C. Frohlich, P. Hauser, M. Liebendoerfer, G. Mart'inez-Pinedo, Friedrich-Karl Thielemann, E. Bravo, Nikolaj Thomas Zinner, W. Hix, K. Langanke, A. Mezzacappa and 1 more. 2004

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With currently known input physics and computer simulations in one dimension, a self-consistent treatment of core-collapse supernovae does not yet lead to successful explosions, while two-dimensional models show some promise. Thus, there are strong indications that the delayed neutrino mechanism works combined with a multidimensional convection treatment for unstable layers (possibly with the aid of rotation, magnetic fields and/or still existent uncertainties in neutrino opacities). On the other hand, there is a need to provide correct nucleosynthesis abundances for the progressing field of galactic evolution and observations of low-metallicity stars. The innermost ejecta is directly affected by the explosion mechanism, i.e., most strongly, the yields of Fe group nuclei for which an induced piston or thermal bomb treatment will not provide the correct yields because the effect of neutrino interactions is not included. We apply parameterized variations to the neutrino-scattering cross sections in order to mimic in one dimension the possible increase of neutrino luminosities caused by uncertainties in proto-neutron star convection. Alternatively, parameterized variations are applied to the neutrino absorption cross sections on nucleons in the "gain region" to mimic the increase in neutrino energy deposition enabled by convective turnover. We find that both measures lead to similar results, causing explosions and a Ye > 0.5 in the innermost ejected layers, due to the combined effect of a short weak-interaction timescale and a negligible electron degeneracy, unveiling the proton-neutron mass difference. We include all weak interactions (electron and positron capture, β-decay, neutrino and antineutrino capture on nuclei, and neutrino and antineutrino capture on nucleons) and present first nucleosynthesis results for these innermost ejected layers to discuss how they improve predictions for Fe group nuclei. The proton-rich environment results in enhanced abundances of 45Sc, 49Ti, and 64Zn as required by chemical evolution studies and observations of low-metallicity stars, as well as appreciable production of nuclei in the mass range up to A = 80.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/ae3aaae717865e5f2e2d99d5f2f22982840a872f

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Citations in the corpus

Nucleosynthesis in Stars and the Chemical Enrichment of Galaxies (2013, background): “In such models, neutrino absorption significantly increases Ye, thereby forming proton-rich ejecta (e.g., Janka, Buras & Rampp 2003; Liebendörfer et al. 2003; Fröhlich et al. 2006).”
Nucleosynthesis-relevant conditions in neutrino-driven supernova outflows. I. Spherically symmetric (2006, methodology): “There are also recent studies (Wanajo et al. 2010; Roberts et al. 2010) of the effect of the reverse shock on the νp-process (Fröhlich et al. 2006; Pruet et al. 2006; Wanajo 2006).”
NUGRID STELLAR DATA SET. I. STELLAR YIELDS FROM H TO BI FOR STARS WITH METALLICITIES Z = 0.02 and Z = 0.01 (2013, background): “…α−rich freezout in CCSN within the high-entropy neutrino winds produced during the formation of a neutron star (e.g., Hoffman et al. 1996; Kratz et al. 2008; Qian & Wasserburg 2008; Farouqi et al. 2010) and the νp process in proton-rich neutrino winds (Fröhlich et al. 2006; Arcones & Montes 2011).”
A NEW MULTI-DIMENSIONAL GENERAL RELATIVISTIC NEUTRINO HYDRODYNAMICS CODE FOR CORE-COLLAPSE SUPERNOVAE. II. RELATIVISTIC EXPLOSION MODELS OF CORE-COLLAPSE SUPERNOVAE (2012, background): “…yields to conform with the established results for proton-rich outflow conditions, i.e. the ejecta composition will be dominated by 56Ni and helium with an admixture of a few rare isotopes (45Sc, 49Ti, and 64Zn) with large production factors (Pruet et al. 2005; Fröhlich et al. 2006b).”
CHARGED-PARTICLE AND NEUTRON-CAPTURE PROCESSES IN THE HIGH-ENTROPY WIND OF CORE-COLLAPSE SUPERNOVAE (2010, methodology): “While in the early phase of core-collapse supernovae a Ye larger than 0.5 is expected (see, e.g., Fröhlich et al. 2006a, 2006b; Pruet et al. 2006), the late phases are expected to experience Ye < 0.5 and enable the onset of an r-process.”
The rp-Process in Neutrino-driven Winds (2006, methodology): “[2]) overcome their inverses, resulting in Ye > 0.5 (see Hoffman et al. 1996; Fröhlich et al. 2006a; Buras et al. 2006, for more detailed discussion).”
Quantifying the uncertainties of chemical evolution studies II. Stellar yields (2010, background): “Furthermore, the reduced Fe yields are consistentwith observations of several type II supernovae (SNeII; Timmes et al. 1995).”
Nucleosynthesis in Early Supernova Winds. II. The Role of Neutrinos (2005, methodology): “As noted before (Paper I; Fröhlich et al. 2006), this implies that the current simulations predict a hot bubble ejecta that could explain the origin of 46, 49Ti and 64Zn.”