Limits on intermediate-mass black holes in six galactic globular clusters with integral-field spectroscopy

Luetzgendorf, N., Kissler-Patig, M., Gebhardt, K., Baumgardt, H., Noyola, E., de Zeeuw, P. T., Neumayer, N., Jalali, B. and Feldmeier, A. (2013) Limits on intermediate-mass black holes in six galactic globular clusters with integral-field spectroscopy. Astronomy and Astrophysics, 552 A49.1-A49.24. doi:10.1051/0004-6361/201220307

Author Luetzgendorf, N.
Kissler-Patig, M.
Gebhardt, K.
Baumgardt, H.
Noyola, E.
de Zeeuw, P. T.
Neumayer, N.
Jalali, B.
Feldmeier, A.
Title Limits on intermediate-mass black holes in six galactic globular clusters with integral-field spectroscopy
Journal name Astronomy and Astrophysics   Check publisher's open access policy
ISSN 0004-6361
Publication date 2013-04
Sub-type Article (original research)
DOI 10.1051/0004-6361/201220307
Open Access Status DOI
Volume 552
Start page A49.1
End page A49.24
Total pages 24
Place of publication Les Ulis, France
Publisher E D P Sciences
Collection year 2014
Language eng
Formatted abstract
Context. The formation of supermassive black holes at high redshift still remains a puzzle to astronomers. No accretion mechanism can explain the fast growth from a stellar mass black hole to several billion solar masses in less than one Gyr. The growth of supermassive black holes becomes reasonable only when starting from a massive seed black hole with mass on the order of 102−105 M. Intermediate-mass black holes are therefore an important field of research. Especially the possibility of finding them in the centers of globular clusters has recently drawn attention. Searching for kinematic signatures of a dark mass in the centers of globular clusters provides a unique test for the existence of intermediate-mass black holes and will shed light on the process of black-hole formation and cluster evolution.

Aims. We are investigating six galactic globular clusters for the presence of an intermediate-mass black hole at their centers. Based on their kinematic and photometric properties, we selected the globular clusters NGC 1851, NGC 1904 (M 79), NGC 5694, NGC 5824, NGC 6093 (M 80), and NGC 6266 (M 62).

Methods. We used integral field spectroscopy to obtain the central velocity-dispersion profile of each cluster. In addition we completed these profiles with outer kinematic points from previous measurements for the clusters NGC 1851, NGC 1094, NGC 5824, and NGC 6093. We also computed the cluster photometric center and the surface brightness profile using HST data. After combining these datasets we compared them to analytic Jeans models. We used varying M/LV profiles for clusters with enough data points in order to reproduce their kinematic profiles in an optimal way. Finally, we varried the mass of the central black hole and tested whether the cluster is better fitted with or without an intermediate-mass black hole.

Results. We present the statistical significance, including upper limits, of the black-hole mass for each cluster. NGC 1904 and NGC 6266 provide the highest significance for a black hole. Jeans models in combination with a M/LV profile obtained from N-body simulations (in the case of NGC 6266) predict a central black hole of M = (3 ± 1) × 103 M for NGC 1904 and M = (2 ± 1) × 103 M for NGC 6266. Furthermore, we discuss the possible influence of dark remnants and mass segregation at the center of the cluster on the detection of an IMBH.
Keyword Black hole physics
Globular clusters: general
Stars: kinematics and dynamics
Surface-brightness profiles
Multi-Gaussian expansion
Young star-clusters
To-light ratio
NGC 1851
Velocity dispersions
Runaway collisions
Central kinematics
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Mathematics and Physics
Official 2014 Collection
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Citation counts: TR Web of Science Citation Count  Cited 25 times in Thomson Reuters Web of Science Article | Citations
Scopus Citation Count Cited 29 times in Scopus Article | Citations
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