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Galaxy interactions in IllustrisTNG-100, I: The power and limitations of visual identification

Blumenthal, Kelly A. and Moreno, Jorge and Barnes, Joshua E. and Hernquist, Lars and Torrey, Paul and Claytor, Zachary and Rodriguez-Gomez, Vicente and Marinacci, Federico and Vogelsberger, Mark (2020) Galaxy interactions in IllustrisTNG-100, I: The power and limitations of visual identification. Monthly Notices of the Royal Astronomical Society, 492 (2). pp. 2075-2094. ISSN 0035-8711. doi:10.1093/mnras/stz3472.

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We present a sample of 446 galaxy pairs constructed using the cosmological simulation IllustrisTNG-100 at z = 0, with M_(FoF,dm)=10¹¹−10^(13.5) M⊙. We produce ideal mock SDSS g-band images of all pairs to test the reliability of visual classification schema employed to produce samples of interacting galaxies. We visually classify each image as interacting or not based on the presence of a close neighbour, the presence of stellar debris fields, disturbed discs, and/or tidal features. By inspecting the trajectories of the pairs, we determine that these indicators correctly identify interacting galaxies ∼45 per cent of the time. We subsequently split the sample into the visually identified interacting pairs (VIP; 38 pairs) and those which are interacting but are not visually identified (nonVIP; 47 pairs). We find that VIP have undergone a close passage nearly twice as recently as the non-VIP, and typically have higher stellar masses. Further, the VIP sit in dark matter haloes that are approximately 2.5 times as massive, in environments nearly 2 times as dense, and are almost a factor of 10 more affected by the tidal forces of their surroundings than the nonVIP. These factors conspire to increase the observability of tidal features and disturbed morphologies, making the VIP more likely to be identified. Thus, merger rate calculations which rely on stellar morphologies are likely to be significantly biased toward massive galaxy pairs which have recently undergone a close passage.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Blumenthal, Kelly A.0000-0002-0893-7194
Hernquist, Lars0000-0001-6950-1629
Torrey, Paul0000-0002-5653-0786
Rodriguez-Gomez, Vicente0000-0002-9495-0079
Marinacci, Federico0000-0003-3816-7028
Vogelsberger, Mark0000-0001-8593-7692
Additional Information:© 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model ( Accepted 2019 December 4. Received 2019 November 5; in original form 2019 May 6. Published: 10 December 2019. KB acknowledges partial support from the National Science Foundation (NSF) Graduate Research Fellowship under Grant No. DGE-1329626. Support for JM is provided by the NSF (AST-1516374), by the Australian Research Council (ARC), and by the Harvard Institute for Theory and Computation, through their Visiting Scholars Program. FM acknowledges support through the Program ‘Rita Levi Montalcini’ of the Italian Ministry of Education, University and Research (MIUR). MV acknowledges support through a Massachusetts Institute of Technology (MIT) Research Support Committee (RSC) award, a Kavli Research Investment Fund, National Aeronautics and Space Administration (NASA) Astrophysics Theory Program (ATP) grant NNX17AG29G, and NSF grants AST-1814053 and AST-1814259. The authors would like to thank the anonymous reviewer, and the Scientific Editor Prof. Joop Schaye, both of whom provided invaluable feedback on the manuscript. In addition, we thank Dylan Nelson and Annalisa Pillepich for their thoughtful comments. The simulation used in this work, TNG100-1, is one of the flagship runs of the IllustrisTNG project, and was run on the HazelHen Cray XC40-system at the High Performance Computing Center Stuttgart as part of project GCS-ILLU of the Gauss Centre for Supercomputing.
Funding AgencyGrant Number
NSF Graduate Research FellowshipDGE-1329626
Australian Research CouncilUNSPECIFIED
Harvard-Smithsonian Center for AstrophysicsUNSPECIFIED
Ministero dell'Istruzione, dell'Universita e della Ricerca (MIUR)UNSPECIFIED
Massachusetts Institute of Technology (MIT)UNSPECIFIED
Kavli FoundationUNSPECIFIED
Subject Keywords:methods: numerical – galaxies: evolution – galaxies: interactions – galaxies: structure
Issue or Number:2
Record Number:CaltechAUTHORS:20200227-133309675
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Official Citation:Kelly A Blumenthal, Jorge Moreno, Joshua E Barnes, Lars Hernquist, Paul Torrey, Zachary Claytor, Vicente Rodriguez-Gomez, Federico Marinacci, Mark Vogelsberger, Galaxy interactions in IllustrisTNG-100, I: The power and limitations of visual identification, Monthly Notices of the Royal Astronomical Society, Volume 492, Issue 2, February 2020, Pages 2075–2094,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:101622
Deposited By: Tony Diaz
Deposited On:27 Feb 2020 21:45
Last Modified:16 Nov 2021 18:04

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