The Uchuu simulations: Data Release 1 and dark matter halo concentrations
We introduce the Uchuu suite of large high-resolution cosmological N-body simulations. The largest simulation, named Uchuu, consists of 2.1 trillion (12 8003) dark matter particles in a box of side-length 2.0 h-1, Gpc$, with particle mass of 3.27 × 108, h-1, M⊙. The highest resolution simulation, Shin-Uchuu, consists of 262 billion (64003) particles in a box of side-length 140 h-1, Mpc, with particle mass of 8.97 × 105, h-1, M⊙. Combining these simulations, we can follow the evolution of dark matter haloes and subhaloes spanning those hosting dwarf galaxies to massive galaxy clusters across an unprecedented volume. In this first paper, we present basic statistics, dark matter power spectra, and the halo and subhalo mass functions, which demonstrate the wide dynamic range and superb statistics of the Uchuu suite. From an analysis of the evolution of the power spectra, we conclude that our simulations remain accurate from the baryon acoustic oscillation scale down to the very small. We also provide parameters of a mass-concentration model, which describes the evolution of halo concentration and reproduces our simulation data to within 5 per cent for haloes with masses spanning nearly eight orders of magnitude at redshift 0 ≤ z ≤ 14. There is an upturn in the mass-concentration relation for the population of all haloes and of relaxed haloes at z ≳ 0.5, whereas no upturn is detected at z < 0.5. We make publicly available various N-body products as part of Uchuu Data Release 1 on the Skies & Universes site. Future releases will include gravitational lensing maps and mock galaxy, X-ray cluster, and active galactic nucleus catalogues. © 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society. ; The Uchuu simulations were carried out on Aterui II supercomputer at Center for Computational Astrophysics, CfCA, of National Astronomical Observatory of Japan, and the K computer at the RIKEN Advanced Institute for Computational Science (Proposal numbers hp180180, hp190161). The Uchuu DR1 effort has made use of the skun6@IAA facility managed by the IAA-CSIC in Spain, this equipment was funded by the Spanish MICINN EU-FEDER infrastructure grant EQC2018-004366-P. The skun@IAA_RedIRIS server was funded by the MICINN grant AYA2014-60641-C2-1-P. The numerical analysis was partially carried out on XC40 at the Yukawa Institute Computer Facility in Kyoto University. TI has been supported by MEXT via the 'Priority Issue on Post-K computer' (Elucidation of the Fundamental Laws and Evolution of the Universe), JICFUS, and MEXT via the 'Program for Promoting Researches on the Supercomputer Fugaku' (Toward a unified view of the universe: from large scale structures to planets, proposal numbers hp200124). TI thanks the support by MEXT/JSPS KAKENHI Grant Numbers JP17H04828, JP18H04337, JP19KK0344, and JP20H05245. FP, AK, and DM thank the support of the Spanish Ministry of Science and Innovation funding grant PGC2018-101931-B-I00. Parts of this research were conducted under the Australian Research Council Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), through project number CE170100013. EJ acknowledges financial support from CNRS. FP and EJ want to thank a French–Spanish international collaboration grant from CNRS and CSIC. CVM acknowledges support from FONDECYT through grant 3200918, and he also acknowledges previous support from the Max Planck Society through a Partner Group grant. SAC acknowledges funding from Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET, PIP-0387), Agencia Nacional de Promoción de la Investigación, el Desarrollo Tecnológico y la Innovación (Agencia I+D+i, PICT-2018-03743), and Universidad Nacional de La Plata (G11-150), Argentina. ; With funding from the Spanish government through the Severo Ochoa Centre of Excellence accreditation SEV-2017-0709. ; Peer reviewed