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Gas sloshing regulates and records the evolution of the Fornax Cluster

Su, Yuanyuan; Nulsen, Paul E.J.; Kraft, Ralph P.; Roediger, Elke; Zuhone, John A.; Jones, Christine; Forman, William R.; Sheardown, Alex; Irwin, Jimmy A.; Randall, Scott W.


Yuanyuan Su

Paul E.J. Nulsen

Ralph P. Kraft

John A. Zuhone

Christine Jones

William R. Forman

Alex Sheardown

Jimmy A. Irwin

Scott W. Randall


We present results of a joint Chandra and XMM-Newton analysis of the Fornax Cluster, the nearest galaxy cluster in the southern sky. Signatures of merger-induced gas sloshing can be seen in the X-ray image. We identify four sloshing cold fronts in the intracluster medium, residing at radii of 3 kpc (west), 10 kpc (northeast), 30 kpc (southwest), and 200 kpc (east). Despite spanning over two orders of magnitude in radius, all four cold fronts fall onto the same spiral pattern that wraps around the BCG NGC 1399, likely all initiated by the infall of NGC 1404. The most evident front is to the northeast, 10 kpc from the cluster center, which separates low-entropy high-metallicity gas and high-entropy low-metallicity gas. The metallicity map suggests that gas sloshing, rather than an AGN outburst, is the driving force behind the redistribution of the enriched gas in this cluster. The innermost cold front resides within the radius of the strong cool core. The sloshing timescale within the cooling radius, calculated from the Brunt–Väsälä frequency, is an order of magnitude shorter than the cooling time. It is plausible that gas sloshing is contributing to the heating of the cool core, provided that gas of different entropies can be mixed effectively via Kelvin–Helmholtz instability. The estimated age of the outermost front suggests that this is not the first infall of NGC 1404.


Su, Y., Nulsen, P. E., Kraft, R. P., Roediger, E., Zuhone, J. A., Jones, C., …Randall, S. W. (2017). Gas sloshing regulates and records the evolution of the Fornax Cluster. The Astrophysical journal, 851(1), 69.

Journal Article Type Article
Acceptance Date Nov 4, 2017
Online Publication Date Dec 13, 2017
Publication Date Dec 13, 2017
Deposit Date Apr 10, 2018
Publicly Available Date Apr 11, 2018
Journal The Astrophysical Journal
Print ISSN 0004-637X
Electronic ISSN 1538-4357
Publisher American Astronomical Society
Peer Reviewed Peer Reviewed
Volume 851
Issue 1
Pages 69
Keywords Space and Planetary Science; Astronomy and Astrophysics
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