Query : 2012A&A...542A.129L

2012A&A...542A.129L - Astronomy and Astrophysics, volume 542A, 129-129 (2012/6-1)

Central kinematics of the globular cluster NGC 2808: upper limit on the mass of an intermediate-mass black hole.


Abstract (from CDS):

Globular clusters are an excellent laboratory for stellar population and dynamical research. Recent studies have shown that these stellar systems are not as simple as previously assumed. With multiple stellar populations as well as outer rotation and mass segregation they turn out to exhibit high complexity. This includes intermediate-mass black holes (IMBHs) which are proposed to sit at the centers of some massive globular clusters. Today's high angular resolution ground based spectrographs allow velocity-dispersion measurements at a spatial resolution comparable to the radius of influence for plausible IMBH masses, and to detect changes in the inner velocity-dispersion profile. Together with high quality photometric data from HST, it is possible to constrain black-hole masses by their kinematic signatures. We determine the central velocity-dispersion profile of the globular cluster NGC 2808 using VLT/FLAMES spectroscopy. In combination with HST/ACS data our goal is to probe whether this massive cluster hosts an IMBH at its center and constrain the cluster mass to light ratio as well as its total mass. We derive a velocity-dispersion profile from integral field spectroscopy in the center and Fabry Perot data for larger radii. High resolution HST data are used to obtain the surface brightness profile. Together, these data sets are compared to dynamical models with varying parameters such as mass to light ratio profiles and black-hole masses. Using analytical Jeans models in combination with variable M/LV profiles from N-body simulations we find that the best fit model is a no black hole solution. After applying various Monte Carlo simulations to estimate the uncertainties, we derive an upper limit of the back hole mass of MBH<1x104M (with 95 % confidence limits) and a global mass-to-light ratio of M/LV=(2.1+/0.2)M/L.

Abstract Copyright:

Journal keyword(s): black hole physics - galaxies: clusters: individual: NGC 2808 - stars: kinematics and dynamics

VizieR on-line data: <Available at CDS (J/A+A/542/A129): fits.dat 2808_ARGUS.fits>

Simbad objects: 6

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Number of rows : 6
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
1 NAME Mayall II GlC 00 32 46.5323801712 +39 34 40.504803060   14.564 13.807 13.208 12.684 ~ 388 1
2 M 31 G 00 42 44.330 +41 16 07.50 4.86 4.36 3.44     ~ 12386 1
3 NGC 2808 GlC 09 12 03.10 -64 51 48.6           ~ 1395 0
4 NGC 5139 GlC 13 26 47.28 -47 28 46.1           ~ 3364 0
5 NGC 6388 GlC 17 36 17.461 -44 44 08.34   7.40       ~ 893 1
6 NAME Local Group GrG ~ ~           ~ 8154 0

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