2025ApJ...995..177T

The mass distribution of binary black holes inferred from gravitational-wave measurements is expected to shed light on their formation mechanisms. An emerging structure in the mass distribution indicates the presence of multiple peaks around chirp masses of 8, 14, and 27 M_⊙. In particular, there is a lack of observations between chirp masses of 10 and 12 M_⊙. In this paper, we report that observations significantly favour the model that supports suppression of the rate in a narrow chirp mass range over the model that does not include suppression, at a confidence greater than 99.5%. Using another test, which measures the deviation between the inferred chirp mass distributions from the two models, we conservatively estimate a 95% confidence in the presence of a feature. A lack of evidence has been reported in the component mass distribution around the comparable location. The differing conclusions are due to a unique correlation between the primary (heavier of the two masses) and the secondary (lighter of the two masses) masses of binary black holes. This correlation results in increased clustering of measured chirp masses around specific values. However, it remains to be ascertained whether this correlation can be attributed to the weak measurability of features in the component masses.