Vol 17, No 8 (2017) / Emberson

Cosmological neutrino simulations at extreme scale

J. D. Emberson, Hao-Ran Yu, Derek Inman, Tong-Jie Zhang, Ue-Li Pen, Joachim Harnois-Deraps, Shuo Yuan, Huan-Yu Teng, Hong-Ming Zhu, Xuelei Chen, Zhi-Zhong Xing

Abstract

Constraining neutrino mass remains an elusive challenge in modern physics. Precision measurements are expected from several upcoming cosmological probes of large-scale structure. Achieving this goal relies on an equal level of precision from theoretical predictions of neutrino clustering. Numerical simulations of the non-linear evolution of cold dark matter and neutrinos play a pivotal role in this process. We incorporate neutrinos into the cosmological N-body code CUBEP3 M and discuss the challenges associated with pushing to the extreme scales demanded by the neutrino problem. We highlight code optimizations made to exploit modern high performance computing architectures and present a novel method of data compression that reduces the phase-space particle footprint from 24 bytes in single precision to roughly 9 bytes. We scale the neutrino problem to the Tianhe-2 supercomputer and provide details of our production run, named TianNu, which uses 86% of the machine (13 824 compute nodes). With a total of 2.97 trillion particles, TianNu is currently the world’s largest cosmological N-body simulation and improves upon previous neutrino simulations by two orders of magnitude in scale. We finish with a discussion of the unanticipated computational challenges that were encountered during the TianNu runtime.

Keywords


cosmology: theory — large-scale structure of universe — methods: numerical

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DOI: https://doi.org/10.1088/1674–4527/17/8/85

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