Were any LIGO black hole mergers actually chance encounters?

Most gravitational-wave models assume black holes spiral together on near-circular orbits, but some may form through chaotic close encounters. Analyzing 26 LIGO-Virgo-KAGRA events with an improved waveform model, five show mild statistical preference for eccentric orbits, and GW190521 — a previously controversial 150-solar-mass merger — shows slight but inconclusive preference for an unbound 'direct capture' origin. The new model is three times faster than its predecessor while being more accurate, making large-scale eccentric searches practical.