  With the growing number of detections of binary black hole mergers, we are
beginning to probe structure in the distribution of masses. A recent study by
Schneider et al. proposes that isolated binary evolution of stripped stars
naturally gives rise to the peaks at chirp masses $\sim 8 M_\odot$, $14
M_\odot$ in the chirp mass distribution and explains the dearth of black holes
between $\approx 10-12 M_\odot$ in chirp mass. The gap in chirp mass results
from an apparent gap in the component mass distribution between $m_1, m_2
\approx 10-15 M_\odot$ and the specific pairing of these black holes. This
component mass gap results from the variation in core compactness of the
progenitor, where a drop in compactness of Carbon-Oxygen core mass will no
longer form black holes from core collapse. We develop a population model
motivated by this scenario to probe the structure of the component mass
distribution of binary black holes consisting of two populations: 1) two peak
components to represent black holes formed in the compactness peaks, and 2) a
powerlaw component to account for any polluting events, these are binaries that
may have formed from different channels (e.g. dynamical). We perform
hierarchical Bayesian inference to analyse the events from the third
gravitational-wave transient catalogue (GWTC-3) with this model. We find that
there is a preference for the lower mass peak to drop off sharply at $\sim 11
M_\odot$ and the upper mass peak to turn on at $\sim 13 M_\odot$, in line with
predictions from Schneider et al. However, there is no clear evidence for a
gap. We also find mild support for the two populations to have different spin
distributions. In addition to these population results, we highlight observed
events of interest that differ from the expected population distribution of
compact objects formed from stripped stars.
