Date post: | 21-Dec-2015 |
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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. 2003 claim a 2000 Msun BH from radial vels
Baumgardt et al. 2003 say no evidence
McNamara et al. 2003 say no evidence from proper motions
• G1
Gebhardt, Rich, & Ho claim 2e4 Msun BH
Baumgardt et al. 2003 say no evidence
New data being analyzed
• NGC 6752
Drukkier et al. 2003 claim large M/L increase from pm’s
Xie et al. 2003 claim little M/L increase from radial vels
Colpi et al. 2003 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 profilefor the 100% and 0% ns population
G1 with WFPC G1 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