S316p.122 — On the uniqueness of kinematical signatures of intermediate-mass black holes in globular clusters

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Aug 10th at 6:00 PM until 7:30 PM




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Author(s): Alice Zocchi1

Institution(s): 1. University of Surrey

Finding an intermediate-mass black hole (IMBH) in a globular cluster (GC), or proving its absence, is a crucial ingredient in our understanding of galaxy formation and evolution. The challenge is to identify a unique signature of an IMBH that cannot be accounted for by other processes. Observational claims of IMBH detection are often based on analyses of the kinematics of stars, such as a rise in the velocity dispersion profile towards the centre of the system. In this contribution we discuss the degeneracy between this IMBH signal and two other factors, namely pressure anisotropy and the presence of a population of stellar mass black holes in the GC. As an example, we analyse the case of Omega Cen by comparing the observed profiles to those calculated from a family of dynamical models that account for the presence of anisotropy and of multi-mass components in the system (Gieles & Zocchi, in preparation). We show that it is possible to partially explain the innermost shape of the projected velocity dispersion profile, even though models that do not account for an IMBH do not exhibit a cusp in the centre.