Mass models of NGC 6624 without an intermediate-mass black hole [GA]

http://arxiv.org/abs/1709.06874


An intermediate-mass black hole (IMBH) was recently reported to reside in the centre of the Galactic globular cluster (GC) NGC6624, based on timing observations of a millisecond pulsar (MSP) located near the cluster centre in projection. We present dynamical models with multiple mass components of NGC6624 – without an IMBH – which successfully describe the surface brightness profile and proper motion kinematics from the Hubble Space Telescope (HST) and the stellar mass function at different distances from the cluster centre. The maximum line-of-sight acceleration at the position of the MSP accommodates the inferred acceleration of the MSP, as derived from its first period derivative. With discrete realisations of the models we show that the higher-order period derivatives – which were previously used to derive the IMBH mass – are due to passing stars and stellar remnants. We conclude that there is no need for an IMBH to explain the timing observations of this MSP.

Read this paper on arXiv…

M. Gieles, E. Balbinot, R. Yaaqib, et. al.
Thu, 21 Sep 17
19/50

Comments: 7 page, 6 figures, resubmitted to MNRAS after favourable referee report