Observational Evidence for Black Holes in Globular Clusters Karl Gebhardt (UT Austin)

Results to Date from Dynamical Studies M15 has been painful for many years Gerssen et al claim a 2000 Msun BH from radial vels Baumgardt et al say no evidence McNamara et al say no evidence from proper motions G1 Gebhardt, Rich, & Ho claim 2e4 Msun BH Baumgardt et al say no evidence New data being analyzed NGC 6752 Drukkier et al claim large M/L increase from pm’s Xie et al claim little M/L increase from radial vels Colpi et al use pulsars to argue for something massive

Current BH/sigma correlation using published results

Comparing M15 radial velocities with proper motions (McNamara et al), using distance as measured from Kraft and Ivans 2003 (11.2 kpc )

Comparison with Baumgardt et al dispersion profile, including a BH of 1700 Msun.

Models with adding a BH to Baumgardt profile for the 100% and 0% ns population

G1 with WFPCG1 with HRC

NGC6752 Pulsar Strangeness

Rotation in Galactic clusters

Central Rotation in Galactic clusters

Central Surface Brightness Profiles

BH/sigma correlation using isotropic models

Conclusions M15 and G1 still have black holes as the best fitting model central light profiles for clusters show a range of slopes rotation in clusters is important to consider many clusters show a statistically significant increase in the central rotation, which has a PA that is not correlated with that of the main body rotation