TianNu: Simulating the Neutrino Sky

Overview

TianNu stands for the "neutrino sky", a cosmological N-body simulation run on the Tianhe-2 (天河二号) supercomputer. The simulation contains 3 trillion particles and models normal hierachy of neutrino with mass 0.05 eV.

Simulation parameters

Code: CubeP3M
Box size: 1.2 Gpc/h, periodic
Cosmology: flat universe with (Ωb,Ωc,σ8,ns,h)=(0.05,0.27,0.83,0.96,0.67)
Neutrino mass: 0.05 eV
Number of CDM particles: 69123=330225942528
Number of neutrino particles: 138243=2641807540224
Total number of particles: 69123+138243=2972033482752
CDM, neutrino Particle mass: 7×108 M⊙, 3×105 M⊙
Softening length: 13 kpc/h
Starting redshift: 100
Number of nodes used in TH2: 243=13824
Number of cores used in TH2: 24×13824=331776
Real time used in TH2: 52 hours

Visualization

This figure shows a 2D visualization of TianNu at redshift z = 0.01, in terms of column density of CDM and neutrinos in a projection of full-size, but an 8.3 Mpc/h slice of the simulation. As shown in the right-hand-side two colourbars for CDM and neutrinos respectively, the blue-white and orange show respectively CDM and neutrino high column density regions. In the main figure one can see that the bright blue filaments show the CDM large scale structure of the Universe whereas more diffused orange "clouds" trace those filaments on a larger scale.
The bottom left two panels zoom in two 35Mpc/h regions from the main figure. They have similar CDM structure, however the upper structure is surrounding a dense cluster on its bottom side (see in the main figure), as a result it has (δc,δν)=(0.081,0.19) compared to the neutrino-poor region (δc,δν)=(0.44,-0.047). Our result shows that halo (galaxy) properties are different in these two regions.

Click the picture or here for full resolution
This animation displays TianNu tracing structure formation over cosmic history. The animation begins with a depiction of slices of the cold dark matter density field (on the left, in blue) and the neutrino density field (on the right, in red) within a region of the simulation volume roughly 1500 Mpc (5 billion light years) on a side with a depth of 12 Mpc (40 million light years). The movie starts at z = 5 (12.5 billion years ago) and proceeds until the present day, at z = 0. The left panel clearly shows the development of the cold dark matter "cosmic web" while the right panel demonstrates the gravitational clustering of neutrinos around the largest cold dark matter structures. The second part of the animation dives into the simulation, travelling at roughly 1015 times the speed of light, until spinning around one of the largest objects in the simulation volume. This object, with a mass of 1015 that of the Sun, would be associated with a massive galaxy cluster today.


Click the video or here for full resolution
Download this movie (475M)

Science Highlight

https://www.nature.com/articles/s41550-017-0143
https://journals.aps.org/prd/abstract/10.1103/PhysRevD.95.083518
http://iopscience.iop.org/article/10.1088/1674-4527/17/8/85/meta
https://arxiv.org/abs/1711.01379
https://arxiv.org/abs/1712.01002

TianNu Simulation Project Team

Hao-Ran Yu1,2,3
J.D. Emberson3,4
Derek Inman3,5
Tong-Jie Zhang1,6
Ue-Li Pen3,7,8,9
Joachim Harnois-Déraps10,11
Shuo Yuan12
Huan-Yu Teng1
Hong-Ming Zhu13
Xuelei Chen13
Zhi-Zhong Xing14,15
Yunfei Du16,17
Lilun Zhang18
Yutong Lu16,17
XiangKe Liao16

1Department of Astronomy, Beijing Normal University 2Kavli Institute for Astronomy and Astrophysics 3Canadian Institute for Theoretical Astrophysics 4Department of Astronomy and Astrophysics, University of Toronto 5Department of Physics, University of Toronto 6Shandong Provincial Key Laboratory of Biophysics, School of Physics 7Dunlap Institute for Astronomy and Astrophysics, University of Toronto 8Canadian Institute for Advanced Research, Program in Gravitation and Cosmology 9Perimeter Institute for Theoretical Physics 10Scottish University Physics Alliance, Institute for Astronomy, University of Edinburgh 11Department of Physics and Astronomy, the University of British Columbia 12Department of Astronomy, Peking University 13Key Laboratory for Computational Astrophysics, National Astronomical Observatories, CAS 14School of Physical Sciences, University of Chinese Academy of Sciences 15Institute of High Energy Physics, CAS 16School of Computer, National University of Defense Technology 17National Supercomputer Center in Guangzhou, Sun Yat-Sen University 18Institute of Ocean Science and Technology, National University of Defense Technology

Acknowledgments

The TianNu project is partly supported by Beijing Normal University.

Links

Tianhe-2 (wikipedia)
中国超级计算广州中心 National Supercomputing Center in Guangzhou
CubeP3M
CITA homepage
KIAA homepage

Haoran Yu's homepage at CITA