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Galaxy Threshing and the Origin of Intracluster Stellar Objects

Published online by Cambridge University Press:  26 May 2016

Kenji Bekki
Affiliation:
School of physics, University of New Southwales, Sydney, NSW, 2052, Australia
Warrick J. Couch
Affiliation:
School of physics, University of New Southwales, Sydney, NSW, 2052, Australia
Michael J. Drinkwater
Affiliation:
Department of Physics, University of Queensland, Queensland 4072, Australia
Yasuhiro Shioya
Affiliation:
Astronomical Institute, Tohoku University, Sendai, 980-8578, Japan

Abstract

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We numerically investigate the dynamical evolution of non-nucleated dwarf elliptical/spiral galaxies (dE) and nucleated ones (dE,Ns) in clusters of galaxies in order to understand the origin of intracluster stellar objects, such as intracluster stars (ICSs), GCs (ICGCs), and “ultra-compact dwarfs” (UCDs) recently discovered by all-object spectroscopic survey centred on the Fornax cluster of galaxies. We find that the outer stellar components of a nucleated dwarf are removed by the strong tidal field of the cluster, whereas the nucleus manages to survive as a result of its initially compact nature. The developed naked nucleus is found to have physical properties (e.g., size and mass) similar to those observed for UCDs. We also find that the UCD formation process does depend on the radial density profile of the dark halo in the sense that UCDs are less likely to be formed from dwarfs embedded in dark matter halos with central ‘cuspy’ density profiles. Our simulations also suggest that very massive and compact stellar systems can be rapidly and efficiently formed in the central regions of dwarfs through the merging of smaller GCs. GCs initially in the outer part of dE and dE,Ns are found to be stripped to form ICGCs.

Type
Part 1. Census
Copyright
Copyright © Astronomical Society of the Pacific 2004 

References

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