2dF Spectroscopy of M104 Globular Clusters
Abstract
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 1.2 x 1012M_⊙ inside 50 kpc, and a (M/L)B = 30: solid evidence for a dark matter halo in this galaxy.
- Publication:
-
Extragalactic Globular Cluster Systems
- Pub Date:
- 2003
- DOI:
- 10.1007/10857603_47
- arXiv:
- arXiv:astro-ph/0211411
- Bibcode:
- 2003egcs.conf..305B
- Keywords:
-
- Astrophysics
- E-Print:
- 5 pages (6 figures), to appear in the proceedings of "Extragalactic Globular Cluster Systems", August 2002, Garching, ed. M.Kissler-Patig, Springer-Verlag