Facial reconstruction

Search LJMU Research Online

Browse Repository | Browse E-Theses

No evidence for intermediate-mass black holes in the globular clusters $ω$ Cen and NGC 6624

Baumgardt, H, He, C, Sweet, SM, Drinkwater, M, Sollima, A, Hurley, J, Usher, C, Kamann, S, Dalgleish, HS, Dreizler, S and Husser, T-O No evidence for intermediate-mass black holes in the globular clusters $ω$ Cen and NGC 6624. Monthly Notices of the Royal Astronomical Society. ISSN 0035-8711 (Accepted)

[img]
Preview
Text
1907.10845v1.pdf - Accepted Version

Download (706kB) | Preview

Abstract

We compare the results of a large grid of N-body simulations with the surface brightness and velocity dispersion profiles of the globular clusters $\omega$ Cen and NGC 6624. Our models include clusters with varying stellar-mass black hole retention fractions and varying masses of a central intermediate-mass black hole (IMBH). We find that an $\sim 45,000$ M$_\odot$ IMBH, whose presence has been suggested based on the measured velocity dispersion profile of $\omega$ Cen, predicts the existence of about 20 fast-moving, $m>0.5$ M$_\odot$ main-sequence stars with a (1D) velocity $v>60$ km/sec in the central 20 arcsec of $\omega$ Cen. However no such star is present in the HST/ACS proper motion catalogue of Bellini et al. (2017), strongly ruling out the presence of a massive IMBH in the core of $\omega$ Cen. Instead, we find that all available data can be fitted by a model that contains 4.6% of the mass of $\omega$ Cen in a centrally concentrated cluster of stellar-mass black holes. We show that this mass fraction in stellar-mass BHs is compatible with the predictions of stellar evolution models of massive stars. We also compare our grid of $N$-body simulations with NGC 6624, a cluster recently claimed to harbor a 20,000 M$_\odot$ black hole based on timing observations of millisecond pulsars. However, we find that models with $M_{IMBH}>1,000$ M$_\odot$ IMBHs are incompatible with the observed velocity dispersion and surface brightness profile of NGC 6624,ruling out the presence of a massive IMBH in this cluster. Models without an IMBH provide again an excellent fit to NGC 6624.

Item Type: Article
Additional Information: This is a pre-copyedited, author-produced PDF of an article accepted for publication in Monthly Notices of the Royal Astronomical Societyfollowing peer review. The version of record H Baumgardt, C He, S M Sweet, M Drinkwater, A Sollima, J Hurley, C Usher, S Kamann, H Dalgleish, S Dreizler, T-O Husser, No evidence for intermediate-mass black holes in the globular clusters ω Cen and NGC 6624, Monthly Notices of the Royal Astronomical Society, , stz2060, is available online at: https://dx.doi.org/10.1093/mnras/stz2060
Uncontrolled Keywords: astro-ph.GA; astro-ph.GA
Subjects: Q Science > QB Astronomy
Q Science > QC Physics
Divisions: Astrophysics Research Institute
Publisher: Oxford University Press
Related URLs:
Date Deposited: 29 Jul 2019 11:00
Last Modified: 29 Jul 2019 11:00
URI: http://researchonline.ljmu.ac.uk/id/eprint/11130

Actions (login required)

View Item View Item