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A new class of x-ray tails of early-type galaxies and subclusters in galaxy clusters: Slingshot tails versus ram pressure stripped tails

Sheardown, Alex; Fish, Thomas M.; Roediger, Elke; Hunt, Matthew; ZuHone, John; Su, Yuanyuan; Kraft, Ralph P.; Nulsen, Paul; Churazov, Eugene; Forman, William; Jones, Christine; Lyskova, Natalya; Eckert, Dominique; De Grandi, Sabrina


Alex Sheardown

Thomas M. Fish

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Dr Elke Roediger
Senior Lecturer/ Director of Studies for Physics

Matthew Hunt

John ZuHone

Yuanyuan Su

Ralph P. Kraft

Paul Nulsen

Eugene Churazov

William Forman

Christine Jones

Natalya Lyskova

Dominique Eckert

Sabrina De Grandi


We show that there is a new class of gas tails—slingshot tails—that form as a subhalo (i.e., a subcluster or early-type cluster galaxy) moves away from the cluster center toward the apocenter of its orbit. These tails can point perpendicular or even opposite to the subhalo direction of motion, not tracing the recent orbital path. Thus, the observed tail direction can be misleading, and we caution against naive conclusions regarding the subhalo's direction of motion based on the tail direction. A head-tail morphology of a galaxy's or subcluster's gaseous atmosphere is usually attributed to ram pressure stripping, and the widely applied conclusion is that gas stripped tail traces the most recent orbit. However, during the slingshot tail stage, the subhalo is not being ram pressure stripped (RPS) and the tail is shaped by tidal forces more than just the ram pressure. Thus, applying a classic RPS scenario to a slingshot tail leads not only to an incorrect conclusion regarding the direction of motion but also to incorrect conclusions regarding the subhalo velocity, expected locations of shear flows, instabilities, and mixing. We describe the genesis and morphology of slingshot tails using data from binary cluster merger simulations and discuss their observable features and how to distinguish them from classic RPS tails. We identify three examples from the literature that are not RPS tails but slingshot tails and discuss other potential candidates.


Sheardown, A., Fish, T. M., Roediger, E., Hunt, M., ZuHone, J., Su, Y., …De Grandi, S. (2019). A new class of x-ray tails of early-type galaxies and subclusters in galaxy clusters: Slingshot tails versus ram pressure stripped tails. The Astrophysical journal, 874(2), 112.

Journal Article Type Article
Acceptance Date Feb 28, 2019
Online Publication Date Mar 28, 2019
Publication Date Mar 28, 2019
Deposit Date Apr 9, 2019
Publicly Available Date Apr 10, 2019
Journal The Astrophysical Journal
Print ISSN 0004-637X
Publisher American Astronomical Society
Peer Reviewed Peer Reviewed
Volume 874
Issue 2
Pages 112
Keywords Space and Planetary Science; Astronomy and Astrophysics
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© 2019. The American Astronomical Society. All rights reserved.

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