THE r-PROCESS NUCLEOSYNTHESIS IN THE VARIOUS JET-LIKE EXPLOSIONS OF MAGNETOROTATIONAL CORE-COLLAPSE SUPERNOVAE

By N. Nishimura, T. Takiwaki, Friedrich-Karl Thielemann. 2015

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The r-process nucleosynthesis in core-collapse supernovae (CC-SNe) is studied, with a focus on the explosion scenario induced by rotation and strong magnetic fields. Nucleosynthesis calculations are conducted based on magneto-hydrodynamical explosion models with a wide range of parameters for initial rotation and magnetic fields. The explosion models are classified in two different types: prompt-magnetic-jet and delayed-magnetic-jet, for which the magnetic fields of proto-neutron stars (PNSs) during collapse and the core-bounce are strong and comparatively moderate, respectively. Following the hydrodynamical trajectories of each explosion model, we confirmed that r-processes successfully occur in the prompt-magnetic-jets, which produce heavy nuclei including actinides. On the other hand, the r-process in the delayed-magnetic-jet is suppressed, which synthesizes only nuclei up to the second peak ( A ∼ 130 ?> ). Thus, the r-process in the delayed-magnetic-jets could explain only “weak r-process” patterns observed in metal-poor stars rather than the “main r-process,” represented by the solar abundances. Our results imply that CC-SNe are possible astronomical sources of heavy r-process elements if their magnetic fields are strong enough, while weaker magnetic explosions may produce “weak r-process” patterns ( A ≲ 130 ?> ). We show the potential importance and necessity of magneto-rotational SNe for explaining the galactic chemical evolution, as well as abundances of r-process enhanced metal-poor stars. We also examine the effects of the remaining uncertainties in the nature of PNSs due to weak interactions that determine the final neutron-richness of ejecta. Additionally, we briefly discuss radioactive isotope yields in primary jets (e.g., 56Ni), with relation to several optical observation of SNe and relevant high-energy astronomical phenomena.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/75c30284cb64178dcfb7dfb0a8767f48bd6f0983

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Citations in the corpus

The Intermediate r-process in Core-collapse Supernovae Driven by the Magneto-rotational Instability (2016, methodology): “We calculate the time evolution of ejected matter via Lagrangian tracer particles (see, Section 2.3 of Nishimura et al. 2015).”
Production of the entire range of r-process nuclides by black hole accretion disc outflows from neutron star mergers (2016, background): “…is MHD-powered, additional magnetocentrifugal acceleration could substantially reduce the electron fraction of the outflow compared to its value in the purely neutrino-driven case favouring the occurrence of an r-process (e.g. Burrows et al. 2007, Winteler et al. 2012, Nishimura et al. 2015).”
Mass Ejection from the Remnant of a Binary Neutron Star Merger: Viscous-radiation Hydrodynamics Study (2017, methodology): “In our scheme, the temporal evolution of temperature, density, and Ye are obtained by using a tracer particle method (see Nishimura et al. 2015 for details and methodology).”
The Origin of r-process Elements in the Milky Way (2017, background): “…& Schramm (1974), recently gained popularity because the high neutron fraction allows robust production of the 2nd and 3rd r-process peaks (e.g., Freiburghaus et al. 1999; Korobkin et al. 2012; Bauswein et al. 2013; Radice et al. 2016; Thielemann et al. 2017, but see Nishimura et al. 2015).”
The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817. III. Optical and UV Spectra of a Blue Kilonova from Fast Polar Ejecta (2017, background): “Jets in core-collapse supernovae may be an alternative (or additional) site of the r-process (Winteler et al. 2012; Nishimura et al. 2015).”
DETAILED CHEMICAL ABUNDANCES IN THE r-PROCESS-RICH ULTRA-FAINT DWARF GALAXY RETICULUM 2 (2016, background): “…Goriely et al. 2011; Ramirez-Ruiz et al. 2015) or rare r-process events associated with core-collapse supernovae, like magnetically-induced jets from the proto neutron star (e.g., Fujimoto et al. 2008; Nishimura et al. 2015), can produce a few 10−2 M of r-process material and a few 10−5 M of Eu.”
NEUTRINO-DRIVEN WINDS IN THE AFTERMATH OF A NEUTRON STAR MERGER: NUCLEOSYNTHESIS AND ELECTROMAGNETIC TRANSIENTS (2015, background): “…r-process (Arcones et al. 2007; Hüdepohl et al. 2010; Roberts et al. 2010; Fischer et al. 2010; Arcones & Montes 2011; Arcones & Thielemann 2013), though some rare supernovae may plausibly contribute (Fujimoto et al. 2006, 2008; Winteler et al. 2012; Mösta et al. 2014; Nishimura et al. 2015).”