Galaxy Zoo: Morphological Classification of Galaxy Images from the Illustris Simulation

Hugh Dickinson, Lucy Fortson, Chris Lintott, Claudia Scarlata, Kyle Willett, Steven Bamford, Melanie Beck, Carolin Cardamone, Melanie Galloway, Brooke Simmons, William Keel, Sandor Kruk, Karen Masters, Mark Vogelsberger, Paul Torrey, Gregory F. Snyder

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

Modern large-scale cosmological simulations model the universe with increasing sophistication and at higher spatial and temporal resolutions. These ongoing enhancements permit increasingly detailed comparisons between the simulation outputs and real observational data. Recent projects such as Illustris are capable of producing simulated images that are designed to be comparable to those obtained from local surveys. This paper tests the degree to which Illustris achieves this goal across a diverse population of galaxies using visual morphologies derived from Galaxy Zoo citizen scientists. Morphological classifications provided by these volunteers for simulated galaxies are compared with similar data for a compatible sample of images drawn from the Sloan Digital Sky Survey (SDSS) Legacy Survey. This paper investigates how simple morphological characterization by human volunteers asked to distinguish smooth from featured systems differs between simulated and real galaxy images. Significant differences are identified, which are most likely due to the limited resolution of the simulation, but which could be revealing real differences in the dynamical evolution of populations of galaxies in the real and model universes. Specifically, for stellar masses M ≲ 1011M, a substantially larger proportion of Illustris galaxies that exhibit disk-like morphology or visible substructure, relative to their SDSS counterparts. Toward higher masses, the visual morphologies for simulated and observed galaxies converge and exhibit similar distributions. The stellar mass threshold indicated by this divergent behavior confirms recent works using parametric measures of morphology from Illustris simulated images. When M ≳ 1011M, the Illustris data set contains substantially fewer galaxies that classifiers regard as unambiguously featured. In combination, these results suggest that comparison between the detailed properties of observed and simulated galaxies, even when limited to reasonably massive systems, may be misleading.

Original languageEnglish (US)
Article number194
JournalAstrophysical Journal
Volume853
Issue number2
DOIs
StatePublished - Feb 1 2018

Fingerprint

zoo
galaxies
simulation
stellar mass
universe
classifiers
substructures
temporal resolution
proportion
spatial resolution
comparison
thresholds
augmentation
output
high resolution

Keywords

  • cosmology: theory
  • galaxies: evolution
  • galaxies: fundamental parameters
  • galaxies: statistics
  • galaxies: structure

Cite this

Galaxy Zoo : Morphological Classification of Galaxy Images from the Illustris Simulation. / Dickinson, Hugh; Fortson, Lucy; Lintott, Chris; Scarlata, Claudia; Willett, Kyle; Bamford, Steven; Beck, Melanie; Cardamone, Carolin; Galloway, Melanie; Simmons, Brooke; Keel, William; Kruk, Sandor; Masters, Karen; Vogelsberger, Mark; Torrey, Paul; Snyder, Gregory F.

In: Astrophysical Journal, Vol. 853, No. 2, 194, 01.02.2018.

Research output: Contribution to journalArticle

Dickinson, H, Fortson, L, Lintott, C, Scarlata, C, Willett, K, Bamford, S, Beck, M, Cardamone, C, Galloway, M, Simmons, B, Keel, W, Kruk, S, Masters, K, Vogelsberger, M, Torrey, P & Snyder, GF 2018, 'Galaxy Zoo: Morphological Classification of Galaxy Images from the Illustris Simulation', Astrophysical Journal, vol. 853, no. 2, 194. https://doi.org/10.3847/1538-4357/aaa250
Dickinson, Hugh ; Fortson, Lucy ; Lintott, Chris ; Scarlata, Claudia ; Willett, Kyle ; Bamford, Steven ; Beck, Melanie ; Cardamone, Carolin ; Galloway, Melanie ; Simmons, Brooke ; Keel, William ; Kruk, Sandor ; Masters, Karen ; Vogelsberger, Mark ; Torrey, Paul ; Snyder, Gregory F. / Galaxy Zoo : Morphological Classification of Galaxy Images from the Illustris Simulation. In: Astrophysical Journal. 2018 ; Vol. 853, No. 2.
@article{0508212b0ec147c2a991fec7c4480412,
title = "Galaxy Zoo: Morphological Classification of Galaxy Images from the Illustris Simulation",
abstract = "Modern large-scale cosmological simulations model the universe with increasing sophistication and at higher spatial and temporal resolutions. These ongoing enhancements permit increasingly detailed comparisons between the simulation outputs and real observational data. Recent projects such as Illustris are capable of producing simulated images that are designed to be comparable to those obtained from local surveys. This paper tests the degree to which Illustris achieves this goal across a diverse population of galaxies using visual morphologies derived from Galaxy Zoo citizen scientists. Morphological classifications provided by these volunteers for simulated galaxies are compared with similar data for a compatible sample of images drawn from the Sloan Digital Sky Survey (SDSS) Legacy Survey. This paper investigates how simple morphological characterization by human volunteers asked to distinguish smooth from featured systems differs between simulated and real galaxy images. Significant differences are identified, which are most likely due to the limited resolution of the simulation, but which could be revealing real differences in the dynamical evolution of populations of galaxies in the real and model universes. Specifically, for stellar masses M∗ ≲ 1011M, a substantially larger proportion of Illustris galaxies that exhibit disk-like morphology or visible substructure, relative to their SDSS counterparts. Toward higher masses, the visual morphologies for simulated and observed galaxies converge and exhibit similar distributions. The stellar mass threshold indicated by this divergent behavior confirms recent works using parametric measures of morphology from Illustris simulated images. When M∗ ≳ 1011M, the Illustris data set contains substantially fewer galaxies that classifiers regard as unambiguously featured. In combination, these results suggest that comparison between the detailed properties of observed and simulated galaxies, even when limited to reasonably massive systems, may be misleading.",
keywords = "cosmology: theory, galaxies: evolution, galaxies: fundamental parameters, galaxies: statistics, galaxies: structure",
author = "Hugh Dickinson and Lucy Fortson and Chris Lintott and Claudia Scarlata and Kyle Willett and Steven Bamford and Melanie Beck and Carolin Cardamone and Melanie Galloway and Brooke Simmons and William Keel and Sandor Kruk and Karen Masters and Mark Vogelsberger and Paul Torrey and Snyder, {Gregory F.}",
year = "2018",
month = "2",
day = "1",
doi = "10.3847/1538-4357/aaa250",
language = "English (US)",
volume = "853",
journal = "Astrophysical Journal",
issn = "0004-637X",
publisher = "IOP Publishing Ltd.",
number = "2",

}

TY - JOUR

T1 - Galaxy Zoo

T2 - Morphological Classification of Galaxy Images from the Illustris Simulation

AU - Dickinson, Hugh

AU - Fortson, Lucy

AU - Lintott, Chris

AU - Scarlata, Claudia

AU - Willett, Kyle

AU - Bamford, Steven

AU - Beck, Melanie

AU - Cardamone, Carolin

AU - Galloway, Melanie

AU - Simmons, Brooke

AU - Keel, William

AU - Kruk, Sandor

AU - Masters, Karen

AU - Vogelsberger, Mark

AU - Torrey, Paul

AU - Snyder, Gregory F.

PY - 2018/2/1

Y1 - 2018/2/1

N2 - Modern large-scale cosmological simulations model the universe with increasing sophistication and at higher spatial and temporal resolutions. These ongoing enhancements permit increasingly detailed comparisons between the simulation outputs and real observational data. Recent projects such as Illustris are capable of producing simulated images that are designed to be comparable to those obtained from local surveys. This paper tests the degree to which Illustris achieves this goal across a diverse population of galaxies using visual morphologies derived from Galaxy Zoo citizen scientists. Morphological classifications provided by these volunteers for simulated galaxies are compared with similar data for a compatible sample of images drawn from the Sloan Digital Sky Survey (SDSS) Legacy Survey. This paper investigates how simple morphological characterization by human volunteers asked to distinguish smooth from featured systems differs between simulated and real galaxy images. Significant differences are identified, which are most likely due to the limited resolution of the simulation, but which could be revealing real differences in the dynamical evolution of populations of galaxies in the real and model universes. Specifically, for stellar masses M∗ ≲ 1011M, a substantially larger proportion of Illustris galaxies that exhibit disk-like morphology or visible substructure, relative to their SDSS counterparts. Toward higher masses, the visual morphologies for simulated and observed galaxies converge and exhibit similar distributions. The stellar mass threshold indicated by this divergent behavior confirms recent works using parametric measures of morphology from Illustris simulated images. When M∗ ≳ 1011M, the Illustris data set contains substantially fewer galaxies that classifiers regard as unambiguously featured. In combination, these results suggest that comparison between the detailed properties of observed and simulated galaxies, even when limited to reasonably massive systems, may be misleading.

AB - Modern large-scale cosmological simulations model the universe with increasing sophistication and at higher spatial and temporal resolutions. These ongoing enhancements permit increasingly detailed comparisons between the simulation outputs and real observational data. Recent projects such as Illustris are capable of producing simulated images that are designed to be comparable to those obtained from local surveys. This paper tests the degree to which Illustris achieves this goal across a diverse population of galaxies using visual morphologies derived from Galaxy Zoo citizen scientists. Morphological classifications provided by these volunteers for simulated galaxies are compared with similar data for a compatible sample of images drawn from the Sloan Digital Sky Survey (SDSS) Legacy Survey. This paper investigates how simple morphological characterization by human volunteers asked to distinguish smooth from featured systems differs between simulated and real galaxy images. Significant differences are identified, which are most likely due to the limited resolution of the simulation, but which could be revealing real differences in the dynamical evolution of populations of galaxies in the real and model universes. Specifically, for stellar masses M∗ ≲ 1011M, a substantially larger proportion of Illustris galaxies that exhibit disk-like morphology or visible substructure, relative to their SDSS counterparts. Toward higher masses, the visual morphologies for simulated and observed galaxies converge and exhibit similar distributions. The stellar mass threshold indicated by this divergent behavior confirms recent works using parametric measures of morphology from Illustris simulated images. When M∗ ≳ 1011M, the Illustris data set contains substantially fewer galaxies that classifiers regard as unambiguously featured. In combination, these results suggest that comparison between the detailed properties of observed and simulated galaxies, even when limited to reasonably massive systems, may be misleading.

KW - cosmology: theory

KW - galaxies: evolution

KW - galaxies: fundamental parameters

KW - galaxies: statistics

KW - galaxies: structure

UR - http://www.scopus.com/inward/record.url?scp=85042013281&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85042013281&partnerID=8YFLogxK

U2 - 10.3847/1538-4357/aaa250

DO - 10.3847/1538-4357/aaa250

M3 - Article

AN - SCOPUS:85042013281

VL - 853

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 2

M1 - 194

ER -