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Galaxy morphology and star formation in the Illustris Simulation at z = 0

Snyder, Gregory F. and Torrey, Paul and Lotz, Jennifer M. and Genel, Shy and McBride, Cameron K. and Vogelsberger, Mark and Pillepich, Annalisa and Nelson, Dylan and Sales, Laura V. and Sijacki, Debora and Hernquist, Lars and Springel, Volker (2015) Galaxy morphology and star formation in the Illustris Simulation at z = 0. Monthly Notices of the Royal Astronomical Society, 454 (2). pp. 1886-1908. ISSN 0035-8711.

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We study how optical galaxy morphology depends on mass and star formation rate (SFR) in the Illustris Simulation. To do so, we measure automated galaxy structures in 10 808 simulated galaxies at z = 0 with stellar masses 10^(9.7) < M_*/M_⊙ < 10^(12.3). We add observational realism to idealized synthetic images and measure non-parametric statistics in rest-frame optical and near-IR images from four directions. We find that Illustris creates a morphologically diverse galaxy population, occupying the observed bulge strength locus and reproducing median morphology trends versus stellar mass, SFR, and compactness. Morphology correlates realistically with rotation, following classification schemes put forth by kinematic surveys. Type fractions as a function of environment agree roughly with data. These results imply that connections among mass, star formation, and galaxy structure arise naturally from models matching global star formation and halo occupation functions when simulated with accurate methods. This raises a question of how to construct experiments on galaxy surveys to better distinguish between models. We predict that at fixed halo mass near 10^(12) M_⊙, disc-dominated galaxies have higher stellar mass than bulge-dominated ones, a possible consequence of the Illustris feedback model. While Illustris galaxies at M_* ∼ 10^(11) M_⊙ have a reasonable size distribution, those at M_* ∼ 10^(10) M_⊙ have half-light radii larger than observed by a factor of 2. Furthermore, at M_* ∼ 10^(10.5)–10^(11) M_⊙, a relevant fraction of Illustris galaxies have distinct 'ring-like' features, such that the bright pixels have an unusually wide spatial extent.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper Information
Torrey, Paul0000-0002-5653-0786
Genel, Shy0000-0002-3185-1540
Pillepich, Annalisa0000-0003-1065-9274
Springel, Volker0000-0001-5976-4599
Additional Information:© 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2015 September 6. Received 2015 September 1. In original form 2015 February 26. First published online October 8, 2015. For discussions that contributed to this paper, we thank Chris Hayward, Ann Zabludoff, Joel Primack, Michael Peth, S. Alireza Mortazavi, Rachel Somerville, Roger Davies, David Spergel, Susan Kassin, and Harry Ferguson. We thank the anonymous referee for a constructive and productive review. We thank Patrik Jonsson for writing, updating, and supporting the SUNRISE code, which we used extensively in this work. LH acknowledges support from NASA grant NNX12AC67G and NSF grant AST-1312095. VS acknowledges support by the European Research Council through ERC-StG grant EXAGAL-308037. GFS and JML appreciate support from HST grant numbers HST-AR-12856.01-A and HST-AR-13887.004-A. SG acknowledges support provided by NASA through Hubble Fellowship grant HST-HF2-51341.001-A. Support for the Hubble Fellowship and HST programmes no. 12856 (PI J. Lotz) and no. 13887 (PI G. Snyder) was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. The computations in this paper were run on the Odyssey cluster supported by the FAS Division of Science, Research Computing Group at Harvard University. This research has made use of NASA's Astrophysics Data System, the Flexible Image Transport System (FITS; Wells, Greisen & Harten 1981; Hanisch et al. 2001) standard, the PYFITS PYTHON module, the SCIPY library (Jones et al. 2001), and ASTROPY (Robitaille et al. 2013). Figures in this paper were constructed with the MATPLOTLIB PYTHON module (Hunter 2007). We used SDSS data as backgrounds for one form of synthetic images. Funding for SDSS-III has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, and the US Department of Energy Office of Science. The SDSS-III web site is SDSS-III is managed by the Astrophysical Research Consortium for the Participating Institutions of the SDSS-III Collaboration including the University of Arizona, the Brazilian Participation Group, Brookhaven National Laboratory, Carnegie Mellon University, University of Florida, the French Participation Group, the German Participation Group, Harvard University, the Instituto de Astrofisica de Canarias, the Michigan State/Notre Dame/JINA Participation Group, Johns Hopkins University, Lawrence Berkeley National Laboratory, Max Planck Institute for Astrophysics, Max Planck Institute for Extraterrestrial Physics, New Mexico State University, New York University, Ohio State University, Pennsylvania State University, University of Portsmouth, Princeton University, the Spanish Participation Group, University of Tokyo, University of Utah, Vanderbilt University, University of Virginia, University of Washington, and Yale University.
Funding AgencyGrant Number
European Research Council (ERC)EXAGAL-308037
Hubble Space Telescope (HST)HST-AR-12856.01-A
Hubble Space Telescope (HST)HST-AR-13887.004-A
Hubble FellowshipHST-HF2-51341.001-A
NASANAS 5-26555
Alfred P. Sloan FoundationUNSPECIFIED
Department of Energy (DOE)UNSPECIFIED
Subject Keywords:methods: numerical galaxies: formation galaxies: statistics galaxies: structure
Record Number:CaltechAUTHORS:20160205-083242503
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Official Citation:Gregory F. Snyder, Paul Torrey, Jennifer M. Lotz, Shy Genel, Cameron K. McBride, Mark Vogelsberger, Annalisa Pillepich, Dylan Nelson, Laura V. Sales, Debora Sijacki, Lars Hernquist, and Volker Springel Galaxy morphology and star formation in the Illustris Simulation at z = 0 MNRAS (December 01, 2015) Vol. 454 1886-1908 doi:10.1093/mnras/stv2078 First published online October 8, 2015
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:64256
Deposited By: Ruth Sustaita
Deposited On:05 Feb 2016 18:36
Last Modified:18 Apr 2017 19:04

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