Stripped elliptical galaxies as probes of ICM physics: I. Tails, wakes, and flow patterns in and around stripped ellipticals

Roediger, E..; Churazov, E..; Kraft, R. P..; Nulsen, P. E.J..; Forman, W. R..; Machacek, M..; Randall, S..; Jones, C..; Kokotanekova, R..; Nulsen, P. E. J..

doi:10.1088/0004-637X/806/1/103

Authors

P. E.J. Nulsen

Dr Elke Roediger E.Roediger@hull.ac.uk
Senior Lecturer/ Director of Studies for Physics

R. P. Kraft

P. E. J. Nulsen

W. R. Forman

M. Machacek

S. Randall

C. Jones

E. Churazov

R. Kokotanekova

Abstract

Elliptical cluster galaxies are progressively stripped of their atmospheres due to their motion through the intra-cluster medium (ICM). Deep X-ray observations reveal the fine-structure of the galaxy's remnant atmosphere and its gas tail and wake. This fine-structure depends on dynamic conditions (galaxy potential, initial gas contents, orbit through the host cluster), orbital stage (early infall, pre-/post-pericenter passage), and ICM plasma properties (thermal conductivity, viscosity, magnetic field structure). We aim to disentangle dynamic and plasma effects in order to use stripped ellipticals as probes of ICM plasma properties. This first paper of a series investigates the hydrodynamics of progressive gas stripping by means of inviscid hydrodynamical simulations. We distinguish a long-lasting initial relaxation phase and a quasi-steady stripping phase. During quasi-steady stripping, the ICM flow around the remnant atmosphere resembles the flow around solid bodies, including a `deadwater' region in the near wake. Gas is stripped from the remnant atmosphere predominantly at its sides via Kelvin-Helmholtz instabilities. The downstream atmosphere is largely shielded from the ICM wind and thus shaped into a tail. Observationally, both, this `remnant tail' and the stripped gas in the wake can appear as a `tail', but only in the wake can galactic gas mix with the ambient ICM. While the qualitative results are generic, the simulations presented here are tailored to the Virgo elliptical galaxy M89 (NGC 4552) for the most direct comparison to observations. Papers II and III of this series describe the effect of viscosity and compare to Chandra and XMM-Newton observations, respectively.

Journal Article Type	Article
Publication Date	Jun 10, 2015
Journal	Astrophysical journal
Print ISSN	0004-637X
Electronic ISSN	1538-4357
Publisher	American Astronomical Society
Peer Reviewed	Peer Reviewed
Volume	806
Issue	1
Article Number	ARTN 103
Institution Citation	Roediger, E., Kraft, R. P., Nulsen, P. E. J., Forman, W. R., Machacek, M., Randall, S., …Kokotanekova, R. (2015). Stripped elliptical galaxies as probes of ICM physics: I. Tails, wakes, and flow patterns in and around stripped ellipticals. The Astrophysical journal, 806(1), https://doi.org/10.1088/0004-637X/806/1/103
DOI	https://doi.org/10.1088/0004-637X/806/1/103
Keywords	Galaxies: clusters: individual (Virgo), Galaxies: individual (M89), Hydrodynamics, Methods: numerical, X-rays: galaxies, X-rays: galaxies: clusters
Publisher URL	http://iopscience.iop.org/article/10.1088/0004-637X/806/1/103/meta
Copyright Statement	© 2015. The American Astronomical Society. All rights reserved.
Additional Information	Copy of article published in: Astrophysical journal, 2015, v.806, issue 1