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Ultra-Compact Dwarf Galaxies – More Massive than Allowed?

Published online by Cambridge University Press:  01 September 2007

Michael Hilker ,
S. Mieske ,
H. Baumgardt  and
J. Dabringhausen
Michael Hilker
Affiliation:
ESO, Karl-Schwarzschild-Str. 2, 85748 Garching bei München, Germany email: mhilker@eso.org, smieske@eso.org
S. Mieske
Affiliation:
ESO, Karl-Schwarzschild-Str. 2, 85748 Garching bei München, Germany email: mhilker@eso.org, smieske@eso.org
H. Baumgardt
Affiliation:
AIfA, Universität Bonn, Auf dem Hügel 71, 53121 Bonn, Germany email: holger@astro.uni-bonn.de, joedab@astro.uni-bonn.de
J. Dabringhausen
Affiliation:
AIfA, Universität Bonn, Auf dem Hügel 71, 53121 Bonn, Germany email: holger@astro.uni-bonn.de, joedab@astro.uni-bonn.de
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Abstract

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Dynamical mass estimates of ultra-compact dwarfs galaxies and massive globular clusters in the Fornax and Virgo clusters and around the giant elliptical Cen A have revealed some surprising results: 1) above ~106M⊙ the mass-to-light (M/L) ratio increases with the objects' mass; 2) some UCDs/massive GCs show high M/L values (4 to 6) that are not compatible with standard stellar population models; and 3) in the luminosity-velocity dispersion diagram, UCDs deviate from the well-defined relation of “normal” GCs, being more in line with the Faber-Jackson relation of early-type galaxies. In this contribution, we present the observational evidences for high mass-to-light ratios of UCDs and discuss possible explanations for them.

Keywords

galaxies: star clustersgalaxies: dwarfgalaxies: kinematics and dynamics
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 3 , Symposium S246: Dynamical Evolution of Dense Stellar Systems , September 2007 , pp. 427 - 428
Copyright
Copyright © International Astronomical Union 2008

References

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