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Radial anisotropy in ω Cen limiting the room for an intermediate-mass black hole

Zocchi, A, Gieles, Mark and Henault-Brunet, V (2017) Radial anisotropy in ω Cen limiting the room for an intermediate-mass black hole Monthly Notices of the Royal Astronomical Society, 468 (4). pp. 4429-4440.

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Finding an intermediate-mass black hole (IMBH) in a globular cluster (or proving its absence) would provide valuable insights into our understanding of galaxy formation and evolution. However, it is challenging to identify a unique signature of an IMBH that cannot be accounted for by other processes. Observational claims of IMBH detection are indeed often based on analyses of the kinematics of stars in the cluster core, the most common signature being a rise in the velocity dispersion profile towards the centre of the system. Unfortunately, this IMBH signal is degenerate with the presence of radially-biased pressure anisotropy in the globular cluster. To explore the role of anisotropy in shaping the observational kinematics of clusters, we analyse the case of ω Cen by comparing the observed profiles to those calculated from the family of LIMEPY models, that account for the presence of anisotropy in the system in a physicallymotivated way. The best-fit radially anisotropicmodels reproduce the observational profiles well, and describe the central kinematics as derived from Hubble Space Telescope proper motions without the need for an IMBH.

Item Type: Article
Subjects : Physics
Divisions : Faculty of Engineering and Physical Sciences > Physics
Authors :
Zocchi, A
Henault-Brunet, V
Date : 7 February 2017
DOI : 10.1093/mnras/stx316
Copyright Disclaimer : Copyright 2017 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society
Uncontrolled Keywords : galaxies: star clusters – globular clusters: general – globular clusters: individual: ω Centauri (NGC 5139) – methods: numerical – stars: kinematics and dynamics
Depositing User : Symplectic Elements
Date Deposited : 07 Feb 2017 15:03
Last Modified : 16 Jan 2019 17:11

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