Simulations predict intermediate-mass black hole formation in globular clusters.

The formation process of intermediate-mass black holes (IMBHs), defined as those between 100 and 10 solar masses (), is debated. One potential origin is the growth of less-massive black holes merging with stars and compact objects within globular clusters (GCs). However, previous simulations have indicated that this process only produces IMBHs under 500 before gravitational wave recoil ejects them from the GC. We performed star-by-star simulations of GC formation, finding that high-density star formation in a GC's parent giant molecular cloud can produce sufficient mergers of massive stars to overcome that mass threshold. We conclude that GCs can form with IMBHs more than 10 , which is sufficiently massive to be retained within the GC even with the expected gravitational wave recoil.