Abstract
Elliptical galaxies contain X-ray emitting gas that is subject to continuous
ram pressure stripping over timescales comparable to cluster ages. The gas in
these galaxies is not in perfect hydrostatic equilibrium. Supernova feedback,
stellar winds, or active galactic nuclei (AGN) feedback can significantly
perturb the interstellar medium (ISM). Using hydrodynamical simulations, we
investigate the effect of subsonic turbulence in the hot ISM on the ram
pressure stripping process in early-type galaxies. We find that galaxies with
the stronger turbulent ISM produce longer, wider, and more smoothly distributed
tails of the stripped ISM than those characterised by weaker ISM turbulence.
Our main conclusion is that even very weak internal turbulence, at the level of
<15% of the average ISM sound speed in a galaxy, can accelerate the gas removal
from the galaxy via ram pressure stripping and remove a significant fraction
(~50%) of the preexisting ISM in ~6 Gyr. The magnitude of this effect increases
sharply with the strength of the turbulence. As most of the gas stripping takes
place near the boundary between the ISM and the intraclustermedium (ICM), the
boost in the ISM stripping rate is due to the "random walk" of the ISM from the
central regions of the galactic potential well to larger distances, where the
ram pressure is able to permanently remove the gas from the galaxy. The ICM can
be temporarily trapped inside the galactic potential well due to the mixing of
the turbulent ISM with the ICM. The galaxies with more turbulent ISM, yet still
characterised by very weak turbulence, can hold larger amounts of the ICM.
Abridged
Description
[1206.6947] Ram pressure stripping in elliptical galaxies: I. the impact of the interstellar medium turbulence
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