  The origin, environment, and evolution of stellar-mass black hole binaries
are still a mystery. One of the proposed binary formation mechanisms is
manifest in dynamical interactions between multiple black holes. A resulting
framework of these dynamical interactions is the so-called hierarchical triple
merger scenario, which happens when three black holes become gravitationally
bound, causing two successive black hole mergers to occur. In such successive
mergers, the black holes involved are directly related to each other, and hence
this channel can be directly tested from the properties of the detected binary
black hole mergers. Here we present a search for hierarchical triple mergers
among events within the GWTC-1 and GWTC-2 catalogs of LIGO/Virgo, the eccentric
localization of GW190521 and those found by the IAS-Princeton group. The search
includes improved statistical quantification that also accounts for black hole
spins. We perform our analysis for different upper bounds on the mass
distribution of first generation BHs. Our results demonstrate the importance of
the mass distributions' properties for constraining the hierarchical merger
scenario. We present the individually significant merger pairs. The search
yields interesting candidate families and hints of its future impact.
