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SkyNet: A Modular Nuclear Reaction Network Library

Lippuner, Jonas and Roberts, Luke F. (2017) SkyNet: A Modular Nuclear Reaction Network Library. Astrophysical Journal Supplement Series, 233 (2). Art. No. 18. ISSN 1538-4365.

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Almost all of the elements heavier than hydrogen that are present in our solar system were produced by nuclear burning processes either in the early universe or at some point in the life cycle of stars. In all of these environments, there are dozens to thousands of nuclear species that interact with each other to produce successively heavier elements. In this paper, we present SkyNet, a new general-purpose nuclear reaction network that evolves the abundances of nuclear species under the influence of nuclear reactions. SkyNet can be used to compute the nucleosynthesis evolution in all astrophysical scenarios where nucleosynthesis occurs. SkyNet is free and open source, and aims to be easy to use and flexible. Any list of isotopes can be evolved, and SkyNet supports different types of nuclear reactions. SkyNet is modular so that new or existing physics, like nuclear reactions or equations of state, can easily be added or modified. Here, we present in detail the physics implemented in SkyNet with a focus on a self-consistent transition to and from nuclear statistical equilibrium to non-equilibrium nuclear burning, our implementation of electron screening, and coupling of the network to an equation of state. We also present comprehensive code tests and comparisons with existing nuclear reaction networks. We find that SkyNet agrees with published results and other codes to an accuracy of a few percent. Discrepancies, where they exist, can be traced to differences in the physics implementations.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Lippuner, Jonas0000-0002-5936-3485
Roberts, Luke F.0000-0001-7364-7946
Additional Information:© 2017 The American Astronomical Society. Received 2017 June 19; revised 2017 October 16; accepted 2017 October 17; published 2017 December 5. We thank J. Austin Harris and W. Raph Hix for giving us access to XNet, for assisting us with running the code comparison tests with XNet, and for helpful discussion of the test results. We are also very grateful to Moritz Reichert, Dirk Martin, Oleg Korobkin, and Marius Eichler for giving us access to WinNet and for helping us run the code comparisons with it. We thank Hendrik Schatz for providing the X-ray burst trajectories and Ivo Seitenzahl for allowing us to use his NSE data. We are very grateful to Christian D. Ott for carefully reading the manuscript and providing helpful comments and suggestions. We also thank our referee, Friedel Thielemann, for the thoughtful comments and additional reference suggestions. L.R. thanks W. Raph Hix and Stan Woosley for many useful discussions concerning nuclear reaction networks and nucleosynthesis. We are indebted to the authors of the sparse linear solver package PARDISO (Schenk & Gärtner 2004, 2006; Karypis & Kumar 1998) for making their code available for free for academic uses. This work was supported in part by the Sherman Fairchild Foundation and NSF awards NSF CAREER PHY-1151197, TCAN AST-1333520, and AST-1205732. The calculations were performed on the Zwicky computer cluster at Caltech, supported by NSF under MRI award PHY-0960291 and by the Sherman Fairchild Foundation. This work benefited from access to the NSF XSEDE computing network under allocation TG-PHY100033 and to NSF/NCSA Blue Waters under NSF PRAC award ACI-1440083. This work was supported in part by NSF grant PHY-1430152 (JINA Center for the Evolution of the Elements).
Group:TAPIR, Walter Burke Institute for Theoretical Physics
Funding AgencyGrant Number
Sherman Fairchild FoundationUNSPECIFIED
Subject Keywords:methods: numerical – nuclear reactions, nucleosynthesis, abundances
Issue or Number:2
Record Number:CaltechAUTHORS:20171205-133353699
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Official Citation:Jonas Lippuner and Luke F. Roberts 2017 ApJS 233 18
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:83694
Deposited By: Tony Diaz
Deposited On:06 Dec 2017 18:05
Last Modified:03 Oct 2019 19:09

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