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Session 52 - Simulations of Clusters of Galaxies.
Display session, Tuesday, January 16
North Banquet Hall, Convention Center

[52.04] 3D Simulations of Galaxies in Clusters : Mass Accretion and Stripping

D. Balsara (N.C.S.A. and Astronomy Dept., Univ. of Illinois, Urbana-Champaign)

The high metallicities found in cluster gas provides strong indication that galaxies moving in cluster gas must have had a strong exchange of their interstellar medium gas with the cluster's gas. Thus understanding the interstellar medium of galaxies in clusters is an intrinsically interesting question. Further interest in this question derives from the fact that magnetic fields have been observed in cluster gas. The turbulence churned up by such galaxies can be a strong source of dynamo action in the cluster gas. The fact that narraow angle tailed radio jets flowing through cluster gas remain synchrotron bright at distances that are well beyond those expected from synchrotron decay time arguments also points to the possibility that a turbulent cluster medium reenergizes them.

Prior 2d simulations by Balsara, Livio and O'Dea (1994) had shown that ellipticals moving through cluster gas produce a pumping mode instability. This instability is a direct analogue to the pumping mode instability observed in Bondi-Hoyle accretion onto white dwarfs and neutron stars in wind-fed systems. Bondi-Hoyle accretion also produces a flip-flop instability in binary star systems. Though the threshold for the onset of this instability is much higher, once it sets in it overwhelms the pumping mode instability. Recent studies have shown that in 3d the flip-flop instability in binary star systems is much diminished. The present study shows that in 3d simulations the flip-flop instability for galaxies is supressed.

Program listing for Tuesday