i-process contribution of rapidly accreting white dwarfs to the solar composition of first-peak neutron-capture elements

Côté, Benoit; Denissenkov, Pavel; Herwig, Falk; Ruiter, Ashley J.; Ritter, Christian; Pignatari, Marco; Belczynski, Krzysztof

Abstract

Rapidly accreting white dwarfs (RAWDs) have been proposed as contributors to the chemical evolution of heavy elements in the Galaxy. Here, we test this scenario for the first time and determine the contribution of RAWDs to the solar composition of first-peak neutron-capture elements. We add the metallicity-dependent contribution of RAWDs to the one-zone galactic chemical evolution code OMEGA according to RAWD rates from binary stellar population models combined with metallicity-dependent i-process stellar yields calculated following the models of Denissenkov et al. With this approach, we find that the contribution of RAWDs to the evolution of heavy elements in the Galaxy could be responsible for a significant fraction of the solar composition of Kr, Rb, Sr, Y, Zr, Nb, and Mo ranging from 2% to 45% depending on the element, the enrichment history of the Galactic gas, and the total mass ejected per RAWD. This contribution could explain the missing solar Lighter Element Primary Process for some elements (e.g., Sr, Y, and Zr). We do not overproduce any isotope relative to the solar composition, but 96Zr is produced in a similar amount. The i process produces efficiently the Mo stable isotopes 95Mo and 97Mo. When nuclear reaction rate uncertainties are combined with our GCE uncertainties, the upper limits for the predicted RAWD contribution increase by a factor of 1.5–2 for Rb, Sr, Y, and Zr, and by 3.8 and 2.4 for Nb and Mo, respectively. We discuss the implication of the RAWD stellar evolution properties on the single-degenerate SN Ia scenario.

Citation

Côté, B., Denissenkov, P., Herwig, F., Ruiter, A. J., Ritter, C., Pignatari, M., & Belczynski, K. (2018). i-process contribution of rapidly accreting white dwarfs to the solar composition of first-peak neutron-capture elements. The Astrophysical journal, 854(2), 1-14. https://doi.org/10.3847/1538-4357/aaaae8

• Journal Article Type: Article
• Acceptance Date: Jan 24, 2018
• Online Publication Date: Feb 16, 2018
• Publication Date: Feb 16, 2018
• Deposit Date: Mar 19, 2018
• Publicly Available Date: Mar 21, 2018
• Journal: The Astrophysical Journal
• Print ISSN: 0004-637X
• Electronic ISSN: 1538-4357
• Publisher: American Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 854
• Issue: 2
• Article Number: 105
• Pages: 1-14
• DOI: https://doi.org/10.3847/1538-4357/aaaae8
• Keywords: Binaries - General; Galaxy - abundances; Nuclear reactions; Nucleosynthesis - abundances; Sun - abundances
• Public URL: https://hull-repository.worktribe.com/output/603798
• Publisher URL: http://iopscience.iop.org/article/10.3847/1538-4357/aaaae8
• Additional Information: Journal title: The Astrophysical Journal; Article type: paper; Article title: i-process Contribution of Rapidly Accreting White Dwarfs to the Solar Composition of First-peak Neutron-capture Elements; Copyright information: © 2018. The American Astronomical Society. All rights reserved.; Date received: 2017-11-29; Date accepted: 2018-01-24; Online publication date: 2018-02-16