We present preliminary results of 2dF spectroscopy of globular clusters in The Sombrero (M104). We find 56 new clusters, and compile a total sample of 103 velocities combined with previous data. Our 2dF data extend out to 20 arcmin radius (~50 kpc), much further than previous studies. In the combined sample, we tentatively find a steep drop in the velocity dispersion with radius, which might possibly indicate a truncated halo. There is no obvious solid-body rotation over all radii, but separate fits for those clusters inside and outside 25 kpc radius show tantalizing evidence for counter-rotation. The projected mass estimator with isotropic orbits yields an M104 mass of 1.2x10^12 solar masses inside 50 kpc, and a (M/L)_B = 30: solid evidence for a dark matter halo in this galaxy.
@article{arxiv.astro-ph/0211411,
title = {2dF Spectroscopy of M104 Globular Clusters},
author = {Terry Bridges and Ken Freeman and Katherine Rhode and Steve Zepf},
journal= {arXiv preprint arXiv:astro-ph/0211411},
year = {2009}
}
Comments
5 pages (6 figures), to appear in the proceedings of "Extragalactic Globular Cluster Systems", August 2002, Garching, ed. M.Kissler-Patig, Springer-Verlag