Globular Clusters as Probes of Galaxy Formation: NGC 4649

Bridges, Terry; Beasley, Mike; Faifer, Favio; Forbes, Duncan; Forte, Juan; Gebhardt, Karl; Hanes, Dave; Norris, Mark; Sharples, Ray; Zepf, Steve
Bibliographical reference

NOAO Proposal ID #2008A-0283

Advertised on:
2
2008
Number of authors
10
IAC number of authors
1
Citations
0
Refereed citations
0
Description
Globular clusters (GCs) provide crucial constraints on galaxy formation models and structure in the Universe, as well as the amount and distribution of galactic dark matter (DM). We request time to double the existing sample of GC velocities for the Virgo elliptical galaxy NGC 4649 from 120 to 250. This increased GC sample will allow the use of the most general possible 3-integral orbit-based models to determine simultaneously the NGC 4649 DM halo profile and the GC orbital anisotropy (for all GCs, and for metal-poor/rich GCs separately), providing an important check on the X-ray derived potential. Using a novel approach pioneered by this group, we will also extract kinematics for the stellar light of NGC 4649 beyond 4 effective radii from the same MOS exposures used in the GC investigation. This combined GC-stellar spectroscopic dataset will be a powerful probe of the DM content, GC orbital anisotropy, and angular momentum of NGC 4649.