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Capturing the 3D motion of an infalling galaxy via fluid dynamics

Su, Yuanyuan; Kraft, Ralph P.; Nulsen, Paul E. J.; Roediger, Elke; Forman, William R.; Churazov, Eugene; Randall, Scott W.; Jones, Christine; Machacek, Marie E.


Eugene Churazov

Christine Jones

Yuanyuan Su

Ralph P. Kraft

Paul E. J. Nulsen

William R. Forman

Scott W. Randall

Marie E. Machacek

Paul E.J. Nulsen


The Fornax Cluster is the nearest galaxy cluster in the southern sky. NGC 1404 is a bright elliptical galaxy falling through the intracluster medium of the Fornax Cluster. The sharp leading edge of NGC 1404 forms a classical "cold front" that separates 0.6 keV dense interstellar medium and 1.5 keV diffuse intracluster medium. We measure the angular pressure variation along the cold front using a very deep (670\,ksec) {\sl Chandra} X-ray observation. We are taking the classical approach -- using stagnation pressure to determine a substructure's speed -- to the next level by not only deriving a general speed but also directionality which yields the complete velocity field as well as the distance of the substructure directly from the pressure distribution. We find a hydrodynamic model consistent with the pressure jump along NGC 1404's atmosphere measured in multiple directions. The best-fit model gives an inclination of 33∘ and a Mach number of 1.3 for the infall of NGC 1404, in agreement with complementary measurements of the motion of NGC 1404. Our study demonstrates the successful treatment of a highly ionized ICM as ideal fluid flow, in support of the hypothesis that magnetic pressure is not dynamically important over most of the virial region of galaxy clusters.

Journal Article Type Article
Publication Date Jan 16, 2017
Journal Astrophysical journal
Print ISSN 0004-637X
Electronic ISSN 1538-4357
Publisher American Astronomical Society
Peer Reviewed Peer Reviewed
Volume 835
Issue 1
Article Number ARTN 19
Pages 19
Keywords X-rays : galaxies : luminosity, Galaxies : ISM, Galaxies : elliptical and lenticular, Clusters of galaxies : intracluster medium
Publisher URL
Additional Information Journal title: The Astrophysical Journal; Article type: paper; Article title: CAPTURING THE 3D MOTION OF AN INFALLING GALAXY VIA FLUID DYNAMICS; Copyright information: © 2017. The American Astronomical Society. All rights reserved.; Date received: 2016-10-02; Date accepted: 2016-11-11; Online publication date: 2017-01-16


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Copyright Statement
© 2017. The American Astronomical Society.

AM - Accepted Manuscript

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