Weak Charge-Changing Flow in Expanding r-Process Environments

Abstract

We assess the prospects for attaining steady nuclear flow equilibrium in expanding r-process environments where beta decay and/or neutrino capture determine the nuclear charge-changing rates. For very rapid expansions, we find that weak steady flow equilibrium normally cannot be attained. However, even when neutron capture processes freeze out in such nonequilibrium conditions, abundance ratios of nuclear species in the r-process peaks might still mimic those attained in weak steady flow. This result suggests that the r-process yield in a regime of rapid expansion can be calculated reliably only when all neutron capture, photodisintegration, and weak interaction processes are fully coupled in a dynamical calculation. We discuss the implications of these results for models of the r-process sited in rapidly expanding neutrino-heated ejecta.

21 pages, AAS LaTex, 2 postscript figures

References in corpus (4)

• Nucleosynthesis in neutrino-driven winds: I. The physical conditions
• Nucleosynthesis in neutrino-driven winds: II. Implications for heavy element synthesis
• Neutrino-induced neutron spallation and supernova r-process nucleosynthesis
• Neutrino-induced nucleosynthesis and the site of the r-process

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• Diverse Supernova Sources for the r-Process
• First-forbidden transitions and stellar $\beta$-decay rates of Zn and Ge isotopes
• Unique first-forbidden $\beta$-decay rates for neutron-rich nickel isotopes in stellar environment
• Neutrino fluence after r-process freeze-out and abundances of Te isotopes in presolar diamonds
• Allowed and unique first-forbidden stellar electron emission rates of neutron-rich copper isotopes