F. N. Bash et al. 2008 The Astronomical Journal 135 182 doi:10.1088/0004-6256/135/1/182
F. N. Bash1, K. Gebhardt1, W. M. Goss2 and P. A. Vanden Bout3
Show affiliationsThe observational evidence for central black holes in globular clusters has been argued extensively, and their existence has important consequences for both the formation and evolution of the cluster. Most of the evidence comes from dynamical arguments, but the interpretation is difficult, given the short relaxation times and old ages of the clusters. One of the most robust signatures for the existence of a BH is radio and/or X-ray emission. We observed three globular clusters: NGC6093 (M80), NGC6266 (M62), and NGC7078 (M15), with the Very Large Array (VLA) in the A and C configuration with a 3-σ noise of 36, 36, and 25 μJy, respectively. We find no statistically significant evidence for radio emission from the central region for any of the three clusters. NGC6266 shows a 2-σ detection. It is difficult to infer a mass from these upper limits due to uncertainty about the central gas density, accretion rate, and accretion model.
accretion, accretion disks; black hole physics; globular clusters: general; radio continuum: general
Issue 1 (2008 January)
Received 2007 July 11, accepted for publication 2007 September 29
Published 2007 December 7
F. N. Bash et al. 2008 The Astronomical Journal 135 182
Alain Comtet et al 2007 J. Phys. A: Math. Theor. 40 11255