Gas sloshing, cold fronts, Kelvin–Helmholtz instabilities and the merger history of the cluster of galaxies Abell 496

Authors

  • E. Roediger,

    Corresponding author
    1. Jacobs University Bremen, PO Box 750 561, 28725 Bremen, Germany
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  • L. Lovisari,

    1. Argelander-Institut für Astronomie, Rheinische Friedrich-Wilhelms-Universität Bonn, Auf dem Hügel 71, D-53121 Bonn, Germany
    2. Institut für Astro- und Teilchenphysik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
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  • R. Dupke,

    1. Department of Astronomy, University of Michigan, 930 Dennison Building, Ann Arbor, MI 48109-1090, USA
    2. Eureka Scientific Inc., Oakland, CA 94602-3017, USA
    3. Observatorio Nacional, Rua Gal. Jose Cristino, 20921-400 Rio de Janeiro, Brazil
    4. University of Alabama, Tuscaloosa, AL 35487-0324, USA
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  • S. Ghizzardi,

    1. INAF, Istituto di Astrofisica Spaziale e Fisica Cosmica, via E. Bassini 15, 20133 Milano, Italy
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  • M. Brüggen,

    1. Jacobs University Bremen, PO Box 750 561, 28725 Bremen, Germany
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  • R. P. Kraft,

    1. Harvard–Smithsonian Center for Astrophysics, 60 Garden Street, MS-4, Cambridge, MA 02138, USA
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  • M. E. Machacek

    1. Harvard–Smithsonian Center for Astrophysics, 60 Garden Street, MS-4, Cambridge, MA 02138, USA
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E-mail: e.roediger@jacobs-university.de

ABSTRACT

We investigate the origin and nature of the multiple sloshing cold fronts in the core of Abell 496 by direct comparison between observations and dedicated hydrodynamical simulations. Our simulations model a minor merger with a 4 × 1013 M subcluster crossing A496 from the south-west to the north–north-east, passing the cluster core in the south-east at a pericentre distance of 100 to a few × 100 kpc about 0.6–0.8 Gyr ago. The gas sloshing triggered by the merger can reproduce almost all observed features, e.g. the characteristic spiral-like brightness residual distribution in the cluster centre and its asymmetry out to 500 kpc, also the positions of and contrasts across the cold fronts. If the subcluster passes close (100 kpc) to the cluster core, the resulting shear flows are strong enough to trigger Kelvin–Helmholtz instabilities that in projection resemble the peculiar kinks in the cold fronts of Abell 496. Finally, we show that sloshing does not lead to a significant modification of the global intracluster medium profiles but a mild oscillation around the initial profiles.

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