Giant Black Holes Likely Formed Through Violent Mergers in Star Clusters
Scientists from Cardiff University have discovered that the universe's largest black holes are likely not born directly from collapsing stars but are instead formed through repeated violent mergers in dense star clusters. Analyzing gravitational-wave signals from the LIGO-Virgo-KAGRA GWTC4 catalog, which includes 153 detections, researchers identified two distinct black hole populations. Lower-mass black holes exhibit slow spins consistent with ordinary stellar collapse, while higher-mass black holes show rapid, randomly oriented spins indicative of hierarchical mergers. This suggests these massive objects are cosmic recyclers, built from previous collisions. The study, published in Nature Astronomy, also provides strong evidence for the pair-instability mass gap around 45 solar masses, a range where direct stellar collapse should not produce black holes. These findings indicate that black holes above this mass threshold are shaped more by cluster dynamics than by individual stellar evolution, offering new insights into the life cycles of massive stars and the structural evolution of star clusters in the universe.
Wire timeline
Giant Black Holes Likely Formed Through Violent Mergers in Star Clusters
Scientists from Cardiff University have discovered that the universe's largest black holes are likely not born directly from collapsing stars but are instead formed through repeated violent mergers in dense star clusters. Analyzing gravitational-wave signals from the LIGO-Virgo-KAGRA GWTC4 catalog, which includes 153 detections, researchers identified two distinct black hole populations. Lower-mass black holes exhibit slow spins consistent with ordinary stellar collapse, while higher-mass black holes show rapid, randomly oriented spins indicative of hierarchical mergers. This suggests these massive objects are cosmic recyclers, built from previous collisions. The study, published in Nature Astronomy, also provides strong evidence for the pair-instability mass gap around 45 solar masses, a range where direct stellar collapse should not produce black holes. These findings indicate that black holes above this mass threshold are shaped more by cluster dynamics than by individual stellar evolution, offering new insights into the life cycles of massive stars and the structural evolution of star clusters in the universe.
Latest Science News -- ScienceDaily