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.

Abstract

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.

Citation

Su, Y., Kraft, R. P., Nulsen, P. E. J., Roediger, E., Forman, W. R., Churazov, E., Randall, S. W., Jones, C., & Machacek, M. E. (2017). Capturing the 3D motion of an infalling galaxy via fluid dynamics. The Astrophysical journal, 835(1), 19. https://doi.org/10.3847/1538-4357/835/1/19

• Journal Article Type: Article
• Acceptance Date: Nov 11, 2016
• Online Publication Date: Jan 16, 2017
• Publication Date: Jan 16, 2017
• Deposit Date: Jan 4, 2017
• Publicly Available Date: Jan 16, 2017
• Journal: Astrophysical journal
• Print ISSN: 0004-637X
• Publisher: American Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 835
• Issue: 1
• Article Number: ARTN 19
• Pages: 19
• DOI: https://doi.org/10.3847/1538-4357/835/1/19
• Keywords: X-rays : galaxies : luminosity, Galaxies : ISM, Galaxies : elliptical and lenticular, Clusters of galaxies : intracluster medium
• Public URL: https://hull-repository.worktribe.com/output/446768
• Publisher URL: http://iopscience.iop.org/article/10.3847/1538-4357/835/1/19/meta
• 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
• Contract Date: Jan 4, 2017