We analyze the gravitational-wave signal GW190521 under the hypothesis that
it was generated by the merger of two nonspinning black holes on hyperbolic
orbits. The best configuration matching the data corresponds to two black holes
of source frame masses of $81^{+62}_{-25}M_\odot$ and $52^{+32}_{-32}M_\odot$
undergoing two encounters and then merging into an intermediate-mass black
hole. Under the hyperbolic merger hypothesis, we find an increase of one unit
in the recovered signal-to-noise ratio and a 14 e-fold increase in the maximum
likelihood value compared to a quasi-circular merger with precessing spins. We
conclude that our results support the first gravitational-wave detection from
the dynamical capture of two stellar-mass black holes.
By Rossella Gamba (TPI)