New Insights into Black Hole Mass Distributions in Binary Systems

A recent paper titled "Two of a Kind: Comparing big and small black holes in binaries with gravitational waves" by Amanda M. Farah, Maya Fishbach, and Daniel E. Holz presents a new analysis of the population of merging binary black holes. Traditionally, studies have concentrated on the distribution of primary black holes, which are the more massive components in these binaries. However, this research emphasizes the significance of the secondary mass distribution, which is crucial for understanding the formation history of coalescing binary black holes.

The authors argue that if both black holes in a binary system undergo similar stellar evolutionary processes before collapsing, their mass distributions should exhibit similar characteristics. Conversely, if they follow different evolutionary paths—possibly due to interactions that disrupt the symmetry between the initially more massive and less massive stars—their mass distributions may diverge.

This paper marks the first effort to explicitly fit for the secondary mass distribution in binary black holes. The findings indicate that the data is consistent with a peak mass of approximately 31.4 solar masses existing primarily in the secondary mass distribution. This observation could have significant implications for our understanding of how these binary systems form. Alternatively, the data may also support the idea that this peak exists in both the primary and secondary mass distributions, a scenario not typically considered in previous studies.

The implications of these findings are substantial, as they challenge existing theories regarding the mass distribution of black holes and their formation processes. The study provides a more nuanced understanding of the relationships between the masses of black holes in binary systems, which could influence future research in astrophysics and our comprehension of the universe's evolution.

For further details, the paper can be accessed at arXiv:2308.05102.