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Picture of Abbas Askar

Abbas Askar

Postdoc

Picture of Abbas Askar

Using binaries in Globular Clusters to catch sight of Intermediate-Mass Black Holes

Author

  • Francisco I Aros
  • Anna C Sippel
  • Alessandra Mastrobuono-battisti
  • Paolo Bianchini
  • Abbas Askar
  • Glenn Van De Ven

Summary, in English

The dynamical evolution of globular clusters (GCs) is tied to their binary population, as binaries segregate to the cluster centre, leading to an increased binary fraction in the core. This central overabundance of mainly hard binaries can serve as a source of energy for the cluster and has a significant effect on the observed kinematics, such as artificially increasing the observed line-of-sight velocity dispersion. We analyse the binary fractions and distributions of 95 simulated GCs, with and without an intermediate-mass black hole (IMBH) in their centre. We show that an IMBH will not only halt the segregation of binaries towards the cluster centre, but also, directly and indirectly, disrupt the binaries that segregate, thus, depleting binaries in the cluster core. We illustrate this by showing that clusters with an IMBH have fewer binaries and flatter radial binary distributions than their counterparts without one. These differences in the binary fraction and distribution provide an additional indicator for the presence of a central IMBH in GCs. In addition, we analyse the effects of the binary fraction on the line-of-sight velocity dispersion in the simulated GCs and find that binaries can cause an overestimation of up to 70percent of the velocity dispersion within the core radius. Using recent VLT/MUSE observations of NGC 3201 by Giesers et al. (2019), we find an overestimation of 32.2±7.8percent in the velocity dispersion that is consistent with the simulations and illustrates the importance of accurately accounting for the binary population when performing kinematic or dynamical analysis.

Department/s

  • Lund Observatory

Publishing year

2021-10-07

Language

English

Pages

4385-4398

Publication/Series

Monthly Notices of the Royal Astronomical Society

Volume

508

Issue

3

Document type

Journal article

Publisher

Oxford University Press

Topic

  • Astronomy, Astrophysics and Cosmology

Status

Published

ISBN/ISSN/Other

  • ISSN: 1365-2966