Sowing the seeds of massive black holes in small galaxies: Young clusters as the building blocks of Ultra-Compact-Dwarf Galaxies

Abstract

Interacting galaxies often have complexes of hundreds of young stellar clusters of individual masses $\sim 10^{4-6}{M}_{\odot }$ in regions that are a few hundred parsecs across. These cluster complexes interact dynamically, and their coalescence is a candidate for the origin of some ultracompact dwarf galaxies (UCDs). Individual clusters with short relaxation times are candidates for the production of intermediate-mass black holes of a few hundred solar masses, via runaway stellar collisions prior to the first supernovae in a cluster. It is therefore possible that a cluster complex hosts multiple intermediate-mass black holes that may be ejected from their individual clusters due to mergers or binary processes, but bound to the complex as a whole. Here we explore the dynamical interaction between initially free-flying massive black holes and clusters in an evolving cluster complex. We find that, after hitting some clusters, it is plausible that the massive black hole will be captured in an ultracompact dwarf forming near the center of the complex. In the process, the hole typically triggers electromagnetic flares via stellar disruptions, and is also likely to be a prominent source of gravitational radiation for the advanced ground-based detectors LIGO and VIRGO. We also discuss other implications of this scenario, notably that the central black hole could be considerably larger than expected in other formation scenarios for ultracompact dwarfs.

15 pages, published in ApJ; for movies, please visit http://members.aei.mpg.de/amaro-seoane/ultra-compact-dwarf-galaxies

References in corpus (11)

• Large Merger Recoils and Spin Flips From Generic Black-Hole Binaries
• Observing IMBH-IMBH Binary Coalescences via Gravitational Radiation
• Superkicks in Hyperbolic Encounters of Binary Black Holes
• Intermediate-mass black holes in colliding clusters: Implications for lower-frequency gravitational-wave astronomy
• The spin expansion for binary black hole merger: new predictions and future directions
• Evolution of Collisionally Merged Massive Stars
• A spectroscopic census of the M82 stellar cluster population
• Modeling maximum astrophysical gravitational recoil velocities
• Modeling Gravitational Recoil Using Numerical Relativity
• MYRIAD: A new N-body code for simulations of Star Clusters
• Gravitational waves from coalescing massive black holes in young dense clusters

Cited by in corpus (10)

• The formation of NGC 3603 young starburst cluster: "prompt" hierarchical assembly or monolithic starburst?
• How can young massive clusters reach their present-day sizes?
• Black hole binary remnant mass and spin: A new phenomenological formula
• Where intermediate-mass black holes could hide in the Galactic Centre: A full parameter study with the S2 orbit
• Dynamical analysis of the dark matter and central black hole mass in the dwarf spheroidal Leo I
• Comparing Remnant Properties from Horizon Data and Asymptotic Data in Numerical Relativity
• Formation of Very Young Massive Clusters and implications for globular clusters
• Mergers all the way down: stellar collisions and kinematics of a dense hierarchically forming massive star cluster in a dwarf starburst
• Accretion from Winds of Red Giant Branch Stars May Reveal the Supermassive Black Hole in Leo I
• Intermediate-mass ratio inspirals in merging elliptical galaxies