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The recent growth history of the Fornax Cluster derived from simultaneous sloshing and gas stripping: Simulating the infall of NGC 1404

Sheardown, Alex; Roediger, Elke; Su, Yuanyuan; Kraft, Ralph P.; Fish, Thomas; ZuHone, John A.; Forman, William R.; Jones, Christine; Churazov, Eugene; Nulsen, Paul E.J.


Alex Sheardown

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Dr Elke Roediger
Senior Lecturer/ Director of Studies for Physics

Yuanyuan Su

Ralph P. Kraft

Thomas Fish

John A. ZuHone

William R. Forman

Christine Jones

Eugene Churazov

Paul E.J. Nulsen


We derive the recent growth history of the Fornax Cluster, in particular the recent infall of the giant elliptical galaxy NGC 1404. We show, using a simple cluster minor merger simulation tailored to Fornax and NGC 1404, that a second or more likely third encounter between the two reproduces all the main merger features observed in both objects; we firmly exclude a first infall scenario. Our simulations reveal a consistent picture: NGC 1404 passed by NGC 1399 about 1.1–1.3 Gyr ago from the northeast to the southwest and is now almost at the point of its next encounter from the south. This scenario explains the sloshing patterns observed in Fornax—a prominent northern cold front and an inner southern cold front. This scenario also explains the truncated atmosphere, the gas-stripping radius of NGC 1404, and its faint gas tail. Independent of the exact history, we can make a number of predictions. A detached bow shock south of NGC 1404 should exist, which is a remnant of the galaxy's previous infall at a distance from NGC 1404 between 450 and 750 kpc with an estimated Mach number between 1.3 and 1.5. The wake of NGC 1404 also lies south of the galaxy with enhanced turbulence and a slight enhancement in metallicity compared to the undisturbed regions of the cluster. Southwest of NGC 1404, there is likely evidence of old turbulence originating from the previous infall. No scenario predicts enhanced turbulence outside of the cold front northwest of the cluster center.

Journal Article Type Article
Publication Date Oct 1, 2018
Journal The Astrophysical Journal
Print ISSN 0004-637X
Electronic ISSN 1538-4357
Publisher American Astronomical Society
Peer Reviewed Peer Reviewed
Volume 865
Issue 2
Article Number 118
Pages 118
APA6 Citation Sheardown, A., Roediger, E., Su, Y., Kraft, R. P., Fish, T., ZuHone, J. A., …Nulsen, P. E. (2018). The recent growth history of the Fornax Cluster derived from simultaneous sloshing and gas stripping: Simulating the infall of NGC 1404. The Astrophysical journal, 865(2), 118.
Keywords Space and Planetary Science; Astronomy and Astrophysics
Publisher URL
Additional Information Journal title: The Astrophysical Journal; Article type: paper; Article title: The Recent Growth History of the Fornax Cluster Derived from Simultaneous Sloshing and Gas Stripping: Simulating the Infall of NGC 1404; Copyright information: © 2018. The American Astronomical Society. All rights reserved.; Date received: 2018-05-18; Date accepted: 2018-08-19; Online publication date: 2018-09-28


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Copyright Statement
© 2018. The American Astronomical Society. All rights reserved.

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