Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.3/81287

Download PDF (Accepted manuscript) (Adobe Acrobat PDF, -1 bytes)

Title

Galaxy threshing and the origin of ultra-compact dwarf galaxies in the Fornax cluster

Author(s)

Bekki, K.;  Couch, W. J.;  Drinkwater, M. J.;  Shioya, Y.

Abstract

A recent all-object spectroscopic survey centred on the Fornax cluster of galaxies has discovered a population of subluminous and extremely compact members, called 'ultra-compact dwarf' (UCD) galaxies. In order to clarify the origin of these objects, we have used self-consistent numerical simulations to study the dynamical evolution a nucleated dwarf galaxy would undergo if orbiting the centre of the Fornax cluster and suffering from its strong tidal gravitational field. 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 although this formation process does not have a strong dependence on the initial total luminosity of the nucleated dwarf, it 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 haloes 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 star clusters. We provide some theoretical predictions on the total number and radial number density profile of UCDs in a cluster and their dependencies on cluster masses.

Publication type

Journal article

Source

Monthly Notices of the Royal Astronomical Society, Vol. 344, no. 2 (Sep 2003), pp. 399-411

Publication year

2003

FOR Code(s)

0201 Astronomical and Space Sciences

Keyword(s)

Cluster galaxies;  Dwarf galaxies;  Elliptical and lenticular galaxies;  Fornax cluster;  Galaxy formation;  Galaxy interactions;  Ultra-compact dwarf galaxies

Publisher

Blackwell

ISSN

1365-2966

Publisher URL

http://dx.doi.org/10.1046/j.1365-8711.2003.06916.x

Copyright

Copyright © 2003 Royal Astronomical Society. The accepted manuscript is reproduced in accordance with the copyright policy of the publisher. The definitive publication is available at www.interscience.wiley.com.

Full text

Peer reviewed