The Ecology of the Galactic Centre: Nuclear Stellar Clusters and Supermassive Black Holes

Abstract

Supermassive black holes are found in most galactic nuclei. A large fraction of these nuclei also contain a nuclear stellar cluster surrounding the black hole. Here we consider the idea that the nuclear stellar cluster formed first and that the supermassive black hole grew later. In particular we consider the merger of three stellar clusters to form a nuclear stellar cluster, where some of these clusters contain a single intermediate-mass black hole (IMBH). In the cases where multiple clusters contain IMBHs, we discuss whether the black holes are likely to merge and whether such mergers are likely to result in the ejection of the merged black hole from the nuclear stellar cluster. In some cases, no supermassive black hole will form as any merger product is not retained. This is a natural pathway to explain those galactic nuclei that contain a nuclear stellar cluster but apparently lack a supermassive black hole; M33 being a nearby example. Alternatively, if an IMBH merger product is retained within the nuclear stellar cluster, it may subsequently grow, e.g. via the tidal disruption of stars, to form a supermassive black hole.

arXiv comment4 pages, 3 figures, 1 table. Contribution to the proceedings of the IAU Symposium No. 351: "Star Clusters: from the Milky Way to the Early Universe"

References in corpus (10)

• The formation of massive black holes through collision runaway in dense young star clusters
• Four-Body Effects in Globular Cluster Black Hole Coalescence
• Runaway collisions in young star clusters. II. Numerical results
• Dissipationless Formation and Evolution of the Milky Way Nuclear Star Cluster
• Improved Dynamical Constraints on the Masses of the Central Black Holes in Nearby Low-mass Early-type Galactic Nuclei And the First Black Hole Determination for NGC 205
• Effects of Intermediate Mass Black Holes on Nuclear Star Clusters
• MOCCA-SURVEY Database I: Assessing GW kick retention fractions for BH-BH mergers in globular clusters
• The impact of stripped Nuclei on the Super-Massive Black Hole number density in the local Universe
• Upper limits on the presence of central massive black holes in two ultra-compact dwarf galaxies in Centaurus A
• MOCCA-SURVEY Database I: Is NGC 6535 a Dark Star Cluster Harboring an IMBH?

Cited by in corpus (2)

• Effect of mass loss due to stellar winds on the formation of supermassive black hole seeds in dense nuclear star clusters
• Dynamically Formed Black Hole Binaries: In-Cluster Versus Ejected Mergers