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The Three Hundred Project: Backsplash galaxies in simulations of clusters

Haggar, Roan; Gray, Meghan E; Pearce, Frazer R; Knebe, Alexander; Cui, Weiguang; Mostoghiu, Robert; Yepes, Gustavo


Roan Haggar

Alexander Knebe

Weiguang Cui

Robert Mostoghiu

Gustavo Yepes


In the outer regions of a galaxy cluster, galaxies may be either falling into the cluster for the first time, or have already passed through the cluster centre at some point in their past. To investigate these two distinct populations, we utilise TheThreeHundred project, a suite of 324 hydrodynamical resimulations of galaxy clusters. In particular, we study the 'backsplash population' of galaxies; those that have passed within R 200 of the cluster centre at some time in their history, but are now outside of this radius. We find that, on average, over half of all galaxies between R 200 and 2R 200 from their host at z = 0 are backsplash galaxies, but that this fraction is dependent on the dynamical state of a cluster, as dynamically relaxed clusters have a greater backsplash fraction. We also find that this population is mostly developed at recent times (z 0.4), and is dependent on the recent history of a cluster. Finally, we show that the dynamical state of a given cluster, and thus the fraction of backsplash galaxies in its outskirts, can be predicted based on observational properties of the cluster.

Journal Article Type Article
Publication Date Mar 1, 2020
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Oxford University Press
Peer Reviewed Peer Reviewed
Volume 492
Issue 4
Pages 6074–6085
APA6 Citation Haggar, R., Gray, M. E., Pearce, F. R., Knebe, A., Cui, W., Mostoghiu, R., & Yepes, G. (2020). The Three Hundred Project: Backsplash galaxies in simulations of clusters. Monthly Notices of the Royal Astronomical Society, 492(4), 6074–6085.
Publisher URL
Additional Information This article has been accepted for publication in MNRAS ©: 2020 The authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.


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