@article{4189348f97144e0e90e3eb43b767e7b3,
title = "nIFTY galaxy cluster simulations - III. The similarity and diversity of galaxies and subhaloes",
abstract = "We examine subhaloes and galaxies residing in a simulated Λ cold dark matter galaxy cluster (Mcrit 200 = 1.1 × 1015 h-1M⊙) produced by hydrodynamical codes ranging from classic smooth particle hydrodynamics (SPH), newer SPH codes, adaptive and moving mesh codes. These codes use subgrid models to capture galaxy formation physics. We compare how well these codes reproduce the same subhaloes/galaxies in gravity-only, non-radiative hydrodynamics and full feedback physics runs by looking at the overall subhalo/galaxy distribution and on an individual object basis. We find that the subhalo population is reproduced to within ≲10 percent for both dark matter only and non-radiative runs, with individual objects showing code-to-code scatter of ≲0.1 dex, although the gas in non-radiative simulations shows significant scatter. Including feedback physics significantly increases the diversity. Subhalo mass and Vmax distributions vary by ≈20 per cent. The galaxy populations also show striking code-to-code variations. Although the Tully-Fisher relation is similar in almost all codes, the number of galaxies with 109 h-1M⊙ ≲ M* ≲ 1012 h-1M⊙ can differ by a factor of 4. Individual galaxies show code-to-code scatter of ~0.5 dex in stellar mass. Moreover, systematic differences exist, with some codes producing galaxies 70 per cent smaller than others. The diversity partially arises from the inclusion/absence of active galactic nucleus feedback. Our results combined with our companion papers demonstrate that subgrid physics is not just subject to fine-tuning, but the complexity of building galaxies in all environments remains a challenge. We argue that even basic galaxy properties, such as stellar mass to halo mass, should be treated with errors bars of ~0.2-0.4 dex.",
keywords = "Dark matter, Galaxies: clusters: general, Methods: numerical",
author = "Elahi, {Pascal J.} and Alexander Knebe and Pearce, {Frazer R.} and Chris Power and Gustavo Yepes and Weiguang Cui and Daniel Cunnama and Kay, {Scott T.} and Federico Sembolini and Beck, {Alexander M.} and Romeel Dav{\'e} and Sean February and Shuiyao Huang and Neal Katz and McCarthy, {Ian G.} and Giuseppe Murante and Valentin Perret and Ewald Puchwein and Alexandro Saro and Romain Teyssier",
note = "Funding Information: The authors thank Joop Schaye for insightful comments. The authors also express special thanks to the Instituto de Fisica Teorica (IFT-UAM/CSIC in Madrid) for its hospitality and support, via the Centro de Excelencia Severo Ochoa Program under grant no. SEV- 2012-0249, during the three week workshop {\textquoteleft}nIFTy Cosmology{\textquoteright} where this work developed. We further acknowledge the financial support of the University of Western 2014 Australia Research Collaboration Award for {\textquoteleft}Fast Approximate Synthetic Universes for the SKA{\textquoteright}, the ARC Centre of Excellence for All Sky Astrophysics (CAASTRO) grant number CE110001020, and the two ARC Discovery Projects DP130100117 and DP140100198. We also recognize support from the Universidad Autonoma de Madrid (UAM) for the workshop infrastructure. PJE is supported by the SSimPL programme and the Sydney Institute for Astronomy (SIfA), and Australian Research Council (ARC) grants DP130100117 and DP140100198. STK acknowledges support from STFC through grant ST/L000768/1. AK is supported by the Ministerio de Econom{\'i}a y Competitividad (MINECO) in Spain through grant AYA2012-31101 as well as the Consolider- Ingenio 2010 Programme of the Spanish Ministerio de Ciencia e Innovaci{\'o}n (MICINN) under grant MultiDark CSD2009-00064. He also acknowledges support from the Australian Research Council (ARC) grants DP130100117 and DP140100198. He further thanks The Feelies for crazy rhythms. CP acknowledges support of the Australian Research Council (ARC) through Future Fellowship FT130100041 and Discovery Project DP140100198. WC and CP acknowledge support of ARC DP130100117. GY and FS acknowledge support from MINECO (Spain) through the grant AYA 2012- 31101. GY thanks also the Red Esp{\~a}nola de Supercomputacion for granting the computing time in the Marenostrum Supercomputer at BSC, where all the MUSIC simulations have been performed. AMB is supported by the DFG Research Unit 1254 {\textquoteleft}Magnetisation of intfirstellar and intergalactic media{\textquoteright} and by the DFG Cluster of Excellence {\textquoteleft}Universe{\textquoteright}. SB and GM acknowledge support from the PRIN-MIUR 2012 Grant {\textquoteleft}The Evolution of Cosmic Baryons{\textquoteright} funded by the Italian Minister of University and Research, by the PRIN-INAF 2012 Grant {\textquoteleft}Multi-scale Simulations of Cosmic Structures{\textquoteright}, by the INFN INDARK Grant and by the {\textquoteleft}Consorzio per la Fisica di Trieste{\textquoteright}. IGM acknowledges support from an STFC Advanced Fellowship. EP acknowledges support by the ERC grant {\textquoteleft}The Emergence of Structure during the epoch of Reionization{\textquoteright}. JS acknowledges support from the European Research Council under the European Union{\textquoteright}s Seventh Framework Programme (FP7/2007- 2013)/ERC grant agreement 278594-GasAroundGalaxies. The authors contributed to this paper in the following ways: PJE organized and analysed the data, made the plots and wrote the paper. AK, GY and FRP organized the nIFTy workshop at which this program was completed. GY supplied the initial conditions. All the other authors, as listed in Section 2 performed the simulations using their codes. All authors have read and commented on the paper. The simulations used for this paper have been run on a variety of supercomputers and are publicly available at the MUSIC website, http://www.music.ft.uam.es. MUSIC simulations were carried out on Marenostrum. AREPO simulations were performed with resources awarded through STFCsDiRACinitiative. The authors thankVolker Springel for helpful discussions and for making AREPO and the original GADGET version available for this project. G3-PESPH Simulations were carried out using resources at the Center for High Performance Computing in Cape Town, South Africa. This research has made use ofNASA{\textquoteright}s Astrophysics Data System (ADS) and the arXiv preprint server. Publisher Copyright: {\textcopyright} 2016 The Authors.",
year = "2016",
month = feb,
day = "22",
doi = "10.1093/mnras/stw338",
language = "English (US)",
volume = "458",
pages = "1096--1116",
journal = "Monthly Notices of the Royal Astronomical Society",
issn = "0035-8711",
publisher = "Oxford University Press",
number = "1",
}