TY - JOUR
T1 - Cosmic Dawn (CoDa)
T2 - The first radiation-hydrodynamics simulation of reionization and galaxy formation in the Local Universe
AU - Ocvirk, Pierre
AU - Gillet, Nicolas
AU - Shapiro, Paul R.
AU - Aubert, Dominique
AU - Iliev, Ilian T.
AU - Teyssier, Romain
AU - Yepes, Gustavo
AU - Choi, Jun Hwan
AU - Sullivan, David
AU - Knebe, Alexander
AU - Gottlöber, Stefan
AU - D'Aloisio, Anson
AU - Park, Hyunbae
AU - Hoffman, Yehuda
AU - Stranex, Timothy
N1 - Funding Information:
support from the French ANR funded project ORAGE (ANR-14-CE33-0016). NG and DA acknowledge funding from the French ANR for project ANR-12-JS05-0001 (EMMA). The CoDa simulation was performed at Oak Ridge National Laboratory/Oak Ridge Leadership Computing Facility on the Titan supercomputer (INCITE 2013 award AST031). Processing was performed on the Eos, Rhea and Lens clusters. Auxiliary simulations used the PRACE-3IP project (FP7 RI-312763) resource curie-hybrid based in France at Très Grand Centre de Calcul. ITI was supported by the Science and Technology Facilities Council [grant number ST/L000652/1]. SG and YH acknowledge support by DFG grant GO 563/21-1. YH has been partially supported by the Israel Science Foundation (1013/12). AK is supported by the Ministerio de Economía y Competitividad and the Fondo Europeo de Desar-rollo Regional (MINECO/FEDER, UE) in Spain through grants AYA2012-31101 and AYA2015-63810-P as well as the Consolider-Ingenio 2010 Programme of the Spanish Ministerio de Ciencia e Innovación (MICINN) under grant MultiDark CSD2009-00064. He also acknowledges support from the Australian Research Council (ARC) grant DP140100198. GY also acknowledges support from MINECO-FEDER under research grants AYA2012-31101 and AYA2015-63810-P. PRS was supported in part by U.S. NSF grant AST-1009799, NASA grant NNX11AE09G, NASA/JPL grant RSA Nos. 1492788 and 1515294, and supercomputer resources from NSF XSEDE grant TG-AST090005 and the Texas Advanced Computing Center (TACC) at the University of Texas at Austin. PO thanks Y. Dubois, F. Roy and Y. Rasera for their precious help dealing with SN feedback in RAMSES and various hacks in pFoF. NG thanks J. Dorval for useful discussions regarding k-d trees which helped with the analysis of this simulation.
Publisher Copyright:
© 2017 The Authors.
PY - 2016/12/1
Y1 - 2016/12/1
N2 - Cosmic reionization by starlight from early galaxies affected their evolution, thereby impacting reionization itself. Star formation suppression, for example, may explain the observed underabundance of Local Group dwarfs relative to N-body predictions for cold dark matter. Reionization modelling requires simulating volumes large enough [~ (100 Mpc)3] to sample reionization 'patchiness', while resolving millions of galaxy sources above ~108 M⊙ combining gravitational and gas dynamics with radiative transfer. Modelling the Local Group requires initial cosmological density fluctuations pre-selected to form the well-known structures of the Local Universe today. Cosmic Dawn ('CoDa') is the first such fully coupled, radiation-hydrodynamics simulation of reionization of the Local Universe. Our new hybrid CPU-GPU code, RAMSES-CUDATON, performs hundreds of radiative transfer and ionization ratesolver timesteps on the GPUs for each hydro-gravity timestep on the CPUs. CoDa simulated (91Mpc)3 with 40963 particles and cells, to redshift 4.23, on ORNL supercomputer Titan, utilizing 8192 cores and 8192 GPUs. Global reionization ended slightly later than observed. However, a simple temporal rescaling which brings the evolution of ionized fraction into agreement with observations also reconciles ionizing flux density, cosmic star formation history, CMB electron scattering optical depth and galaxy UV luminosity function with their observed values. Photoionization heating suppressed the star formation of haloes below ~2 × 109 M⊙, decreasing the abundance of faint galaxies around MAB1600 = [-10, -12]. For most of reionization, star formation was dominated by haloes between 1010-1011 M⊙, so low-mass halo suppression was not reflected by a distinct feature in the global star formation history. Intergalactic filaments display sheathed structures, with hot envelopes surrounding cooler cores, but do not self-shield, unlike regions denser than 100 〈ρ〉.
AB - Cosmic reionization by starlight from early galaxies affected their evolution, thereby impacting reionization itself. Star formation suppression, for example, may explain the observed underabundance of Local Group dwarfs relative to N-body predictions for cold dark matter. Reionization modelling requires simulating volumes large enough [~ (100 Mpc)3] to sample reionization 'patchiness', while resolving millions of galaxy sources above ~108 M⊙ combining gravitational and gas dynamics with radiative transfer. Modelling the Local Group requires initial cosmological density fluctuations pre-selected to form the well-known structures of the Local Universe today. Cosmic Dawn ('CoDa') is the first such fully coupled, radiation-hydrodynamics simulation of reionization of the Local Universe. Our new hybrid CPU-GPU code, RAMSES-CUDATON, performs hundreds of radiative transfer and ionization ratesolver timesteps on the GPUs for each hydro-gravity timestep on the CPUs. CoDa simulated (91Mpc)3 with 40963 particles and cells, to redshift 4.23, on ORNL supercomputer Titan, utilizing 8192 cores and 8192 GPUs. Global reionization ended slightly later than observed. However, a simple temporal rescaling which brings the evolution of ionized fraction into agreement with observations also reconciles ionizing flux density, cosmic star formation history, CMB electron scattering optical depth and galaxy UV luminosity function with their observed values. Photoionization heating suppressed the star formation of haloes below ~2 × 109 M⊙, decreasing the abundance of faint galaxies around MAB1600 = [-10, -12]. For most of reionization, star formation was dominated by haloes between 1010-1011 M⊙, so low-mass halo suppression was not reflected by a distinct feature in the global star formation history. Intergalactic filaments display sheathed structures, with hot envelopes surrounding cooler cores, but do not self-shield, unlike regions denser than 100 〈ρ〉.
KW - Galaxies: formation
KW - Intergalactic medium
KW - Local Group
KW - Methods: numerical
KW - Radiative transfer
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U2 - 10.1093/mnras/stw2036
DO - 10.1093/mnras/stw2036
M3 - Article
AN - SCOPUS:85040249016
SN - 0035-8711
VL - 463
SP - 1462
EP - 1485
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 2
ER -