Title: Uncertainties in νp-process nucleosynthesis from Monte Carlo variation of reaction rates

Abstract

It has been suggested that a νp-process can occur when hot, dense, and proton-rich matter is expanding within a strong flux of antineutrinos. In such an environment, proton-rich nuclides can be produced in sequences of proton captures and (n, p) reactions, where the free neutrons are created in situ by $$\overline{\nu }_\mathrm{e}+\mathrm{p} {\rightarrow} \mathrm{n}+\mathrm{e}^+$$ reactions. The detailed hydrodynamic evolution determines where the nucleosynthesis path turns off from N = Z line and how far up the nuclear chart it runs. In this work, the uncertainties on the final isotopic abundances stemming from uncertainties in the nuclear reaction rates were investigated in a large-scale Monte Carlo approach, simultaneously varying more than 10 000 reactions. A large range of model conditions was investigated because a definitive astrophysical site for the νp-process has not yet been identified. The present parameter study provides, for each model, identification of the key nuclear reactions dominating the uncertainty for a given nuclide abundance. As all rates appearing in the νp-process involve unstable nuclei, and thus only theoretical rates are available, the final abundance uncertainties are larger than those for nucleosynthesis processes closer to stability. Nevertheless, most uncertainties remain below a factor of 3 in trajectories with robust nucleosynthesis. More extreme conditions allow production of heavier nuclides but show larger uncertainties because of the accumulation of the uncertainties in many rates and because the termination of nucleosynthesis is not at equilibrium conditions. It is also found that the solar ratio of the abundances of ⁹²Mo and 94Mo could be reproduced within uncertainties.

Authors:

Nishimura  ^[1];

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Rauscher, T.  ^[2];

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Hirschi, R. ^[3]; Cescutti, G.  ^[4];

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Murphy, A. St J. ^[5]; Fröhlich, C.  ^[6]

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+ Show Author Affiliations

1. (西村信哉), N. [Center for Gravitational Physics, Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502, Japan, Astrophysics Group, Faculty of Natural Sciences, Keele University, Keele ST5 5BG, UK
2. Department of Physics, University of Basel, CH-4056 Basel, Switzerland, Centre for Astrophysics Research, University of Hertfordshire, Hatfield AL10 9AB, UK
3. Astrophysics Group, Faculty of Natural Sciences, Keele University, Keele ST5 5BG, UK, Kavli IPMU (WPI), University of Tokyo, Kashiwa 277-8583, Japan
4. Centre for Astrophysics Research, University of Hertfordshire, Hatfield AL10 9AB, UK, INAF, Osservatorio Astronomico di Trieste, I-34131 Trieste, Italy
5. School of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3FD, UK
6. Department of Physics, North Carolina State University, Raleigh, NC 27695-8202, USA

Publication Date:

2019-08-02

Research Org.:

North Carolina State Univ., Raleigh, NC (United States)

Sponsoring Org.:

USDOE Office of Science (SC)

OSTI Identifier:

1560913

Alternate Identifier(s):

OSTI ID: 1800048

Grant/Contract Number:  

FG02-02ER41216

Resource Type:

Published Article

Journal Name:

Monthly Notices of the Royal Astronomical Society

Additional Journal Information:

Journal Name: Monthly Notices of the Royal Astronomical Society Journal Volume: 489 Journal Issue: 1; Journal ID: ISSN 0035-8711

Publisher:

Oxford University Press

Country of Publication:

United Kingdom

Language:

English

Subject:

79 ASTRONOMY AND ASTROPHYSICS; astronomy & astrophysics; neutrino; nuclear reactions; nucleosynthesis; abundances; stars: neutron; stars: abundances; supernovae: general; Issue Section: Article