Аннотация
(abridged) Elliptical cluster galaxies moving through the ICM are
successively stripped of their gaseous atmospheres. Deep X-ray observations
reveal the detailed structure of galactic tails and wakes and of the interface
between the galactic gas and the ICM. This fine-structure depends on dynamic
conditions (galaxy potential, initial gas contents, orbit in the host cluster),
stripping stage (early infall, pre-/post-pericenter passage), as well as on the
still ill-constrained ICM plasma properties (thermal conductivity, viscosity,
magnetic field structure). The first paper of this series describes flow
patterns and stages of inviscid gas stripping. Here we study the effect of a
Spitzer-like temperature dependent viscosity corresponding to Reynolds numbers,
Re, of 50 to 5000 w.r.t. the ICM flow around the remnant atmosphere. Global
flow patterns are independent of viscosity in this range. Viscosity suppresses
Kelvin-Helmholtz instabilities (KHIs) at the sides of the remaining atmosphere
and prevents mixing of cool stripped gas with the hotter ICM in the galaxy's
wake. Thus, viscously stripped galaxies have long X-ray bright cool wakes. We
provide a collection of mock X-ray images for different stripping stages and
conditions. While these qualitative results are generic, we aim at the most
direct comparison to observations and tailored our simulations to the Virgo
elliptical galaxy M89 (NGC 4552), where Re ~ 50 corresponds to a viscosity of
10% of the Spitzer level. Paper III of this series compares in detail new deep
Chandra and archival XMM-Newton data to our simulations. The comparison
disfavors an isotropic viscosity near the Spitzer value in the Virgo ICM, and
suggests a near pericenter position of M89 in the Virgo cluster.
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