Illuminating black hole cusps in dense stellar environments

The majority of merging black holes observed by LIGO have had surprisingly large masses. The leading hypothesis for explaining these anomalously high masses is that the observed black holes formed and evolved in ancient globular clusters. Pioneering simulations of globular cluster evolution have explored this hypothesis and have unveiled both the spatial distribution and mass spectrum of black hole populations in globular clusters across cosmic age. However, the interaction of the evolving cluster with the hydrodynamics of the ambient gaseous medium has been only marginally explored. In this work, we perform three-dimensional hydrodynamic simulations of black hole cusps accreting from their surrounding gaseous reservoirs. The resulting accretion rates suggest that in certain contexts these populations can harbor appreciable X-ray luminosities. We compare these predictions to observations of ultra-luminous X-ray sources and young massive clusters (commonly thought of as young globular cluster analogues) in nearby gas-rich galaxies such as the Antennae. By making this comparison, we are able to constrain the black hole cusp populations in these systems.