UCDs - more massive than allowed?
Abstract
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 about 10^6 M_sun 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
Cite
@article{arxiv.0710.1691,
title = {UCDs - more massive than allowed?},
author = {M. Hilker and S. Mieske and H. Baumgardt and J. Dabringhausen},
journal= {arXiv preprint arXiv:0710.1691},
year = {2007}
}
Comments
2 pages, 2 figures. To appear in the proceedings of the 246th IAU symposium on 'Dynamical Evolution of Dense Stellar Systems', eds. E. Vesperini, M. Giersz, and A. Sills, Capri, Sept. 2007