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The effect of stellar-mass black holes on the central kinematics of ω Cen: a cautionary tale for IMBH interpretations

Zocchi, Alice, Gieles, Mark and Hénault-Brunet, Vincent (2018) The effect of stellar-mass black holes on the central kinematics of ω Cen: a cautionary tale for IMBH interpretations Monthly Notices of the Royal Astronomical Society.

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The search for intermediate-mass black holes (IMBHs) in the centre of globular clusters is often based on the observation of a central cusp in the surface brightness profile and a rise towards the centre in the velocity dispersion profiles. Similar signatures, however, could result from other effects, that need to be taken into account in order to determine the presence (or the absence) of an IMBH in these stellar systems. Following our previous exploration of the role of radial anisotropy in shaping these observational signatures, we analyse here the effects produced by the presence of a population of centrally concentrated stellar-mass black holes. We fit dynamical models to ω Cen data, and we show that models with ~ 5% of their mass in black holes (consistent with ~ 100% retention fraction after natal kicks) can reproduce the data.When simultaneously considering both radial anisotropy and mass segregation, the bestfit model includes a smaller population of remnants, and a less extreme degree of anisotropy with respect to the models that include only one of these features. These results underline that before conclusions about putative IMBHs can be made, the effects of stellar-mass black holes and radial anisotropy need to be properly accounted for.

Item Type: Article
Divisions : Faculty of Engineering and Physical Sciences > Physics
Authors :
Zocchi, Alice
Hénault-Brunet, Vincent
Date : 12 June 2018
DOI : 10.1093/mnras/sty1508
Copyright Disclaimer : This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society. © 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society
Uncontrolled Keywords : Methods: numerical. Stars: kinematics and dynamics. Globular clusters: general. Globular clusters: individual: ω Centauri (NGC 5139). Galaxies: star clusters: general.
Depositing User : Clive Harris
Date Deposited : 12 Jun 2018 07:14
Last Modified : 07 Nov 2018 08:20

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