The Dynamics of M15: Observations of the Velocity Dispersion Profile and Fokker‐Planck Models

Dull, J. D.; Cohn, H. N.; Lugger, P. M.; Murphy, B. W.; Seitzer, Patrick; Callanan, P. J.; Rutten, R. G. M.; Charles, P. A.

doi:10.1086/304016

Cited by 68 publications

(97 citation statements)

References 37 publications

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“…It is possible to obtain such a profile for example via Fokker-Planck models (e.g. Dull et al 1997Dull et al , 2003 or by N-body simulations. However, this is beyond the scope of this work.…”

Section: Discussionmentioning

confidence: 99%

The central dynamics of M3, M13, and M92: stringent limits on the masses of intermediate-mass black holes

Kamann

Wisotzki

Roth

et al. 2014

A&A

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We used the PMAS integral field spectrograph to obtain large sets of radial velocities in the central regions of three northern Galactic globular clusters: M3, M13, and M92. By applying the novel technique of crowded field 3D spectroscopy, we measured radial velocities for about 80 stars within the central ∼10 of each cluster. These are by far the largest spectroscopic datasets obtained in the innermost parts of these clusters up to now. To obtain kinematical data across the whole extent of the clusters, we complement our data with measurements available in the literature. We combine our velocity measurements with surface brightness profiles to analyse the internal dynamics of each cluster using spherical Jeans models, and investigate whether our data provide evidence for an intermediate-mass black hole in any of the clusters. The surface brightness profiles reveal that all three clusters are consistent with a core profile, although shallow cusps cannot be excluded. We find that spherical Jeans models with a constant mass-to-light ratio provide a good overall representation of the kinematical data. A massive black hole is required in none of the three clusters to explain the observed kinematics. Our 1σ (3σ) upper limits are 5300 M (12 000 M ) for M3, 8600 M (13 000 M ) for M13, and 980 M (2700 M ) for M92. A puzzling circumstance is the existence of several potential high velocity stars in M3 and M13, as their presence can account for the majority of the discrepancies that we find in our mass limits compared to M92.

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Section: Discussionmentioning

confidence: 99%

The central dynamics of M3, M13, and M92: stringent limits on the masses of intermediate-mass black holes

Kamann

Wisotzki

Roth

et al. 2014

A&A

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“…6 The correct treatment yielded a formal mass of ; how-3 1.7 # 10 M , ever, a mass of zero was excluded only at the ∼ level. 1 j 2 In their addendum, Gerssen et al (2003) maintain that a central black hole remains a viable interpretation of the M15 data, citing the probability that most neutron stars would have escaped the cluster on formation, in contradiction to the assumption of 100% neutron star retention made by Dull et al (1997) and also in Figure 3 above. Most neutron stars receive substantial "kicks" at birth (Lyne & Lorimer 1994), which may eject them from their parent cluster.…”

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confidence: 95%

“…Not surprisingly, we find a large discrepancy between the inferred velocity dispersion and the observed profile, as illustrated by the bottom dashed line in Figure 3 Gerssen et al (2002) have analyzed the velocity distribution of the bright stars in M15, using two different methods and averaging the results. They first assume a constant mass-tolight ratio, then adopt a more realistic radial run of mass to light, obtained from Fokker-Planck simulations (Dull et al 1997). Their first method leads to an inferred central black hole mass of , containing a fraction of choice of M15 mass is taken from Dull et al 1997.…”

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confidence: 99%

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On the Central Structure of M15

Baumgardt

Hut

Makino

et al. 2002

ApJ

155

157

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We present a detailed comparison between the latest observational data on the kinematical structure of the core of M15, obtained with the Hubble Space Telescope Space Telescope Imaging Spectrograph and Wide Field Planetary Camera 2 instruments, and the results of dynamical simulations carried out using the special purpose GRAPE-6 computer. The observations imply the presence of a significant amount of dark matter in the cluster core. In our dynamical simulations, neutron stars and/or massive white dwarfs concentrate to the center through mass segregation, resulting in a sharp increase in toward the center. While consistent with the presence of M/L a central black hole, the Hubble Space Telescope data can also be explained by this central concentration of stellar mass compact objects. The latter interpretation is more conservative, since such remnants result naturally from stellar evolution, although runaway merging leading to the formation of a black hole may also occur for some range of initial conditions. We conclude that no central massive object is required to explain the observational data, although we cannot conclusively exclude such an object at the level of ∼ . Our findings are 500-1000 M , unchanged when we reduce the assumed neutron star retention fraction in our simulations from 100% to 0%.

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“…In view of this, and since additional systematic errors might be present, we suggest that the mass of M C is approximately ð4:5 AE 0:5Þ Â 10 5 M . For comparison, Dull et al (1997) obtained a value of M C ¼ 4:9 Â 10 5 M for the mass of M15 based on fits to Fokker-Planck calculations. Sosin & King (1997) found a mass of only M C ¼ 3:4 Â 10 5 M from fits of static King-Michie models to the surface brightness profile in the center.…”

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confidence: 99%

The Dynamical Distance to M15: Estimates of the Cluster’s Age and Mass and of the Absolute Magnitude of Its RR Lyrae Stars

McNamara

Harrison

Baumgardt

2004

ApJ

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Newly determined high-precision relative proper motions determined from the Hubble Space Telescope Wide Field Planetary Camera 2 are used along with radial velocity measurements to determine the dynamical distance to the globular cluster M15. A comparison of the proper motion and radial velocity dispersions from a sample of 237 stars, located at an average radial distance of about 10 00 from the cluster center, yields a cluster distance of 9:98 AE 0:47 kpc. This distance agrees to within the stated errors to other distance estimates but places this object about 5% closer than the currently adopted value of 10.4 kpc. Using this new distance, we estimate that RR Lyrae stars having ½Fe=H ¼ À2:15 have a value of M v ðRRÞ ¼ 0:51 AE 0:11. We also estimate that M15 has an age of about 13.2 Gyr, which places it among the oldest of the Galactic globular clusters. From a comparison of the observed velocity dispersion with results from recent N-body calculations, we derive a total cluster mass for M15 of M C ¼ 4:5 Â 10 5 M .

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The Dynamics of M15: Observations of the Velocity Dispersion Profile and Fokker‐Planck Models

Cited by 68 publications

References 37 publications

The central dynamics of M3, M13, and M92: stringent limits on the masses of intermediate-mass black holes

The central dynamics of M3, M13, and M92: stringent limits on the masses of intermediate-mass black holes

On the Central Structure of M15

The Dynamical Distance to M15: Estimates of the Cluster’s Age and Mass and of the Absolute Magnitude of Its RR Lyrae Stars

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