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GWTC-4.0: Population Properties of Merging Compact Binaries
A. G. Abac et al 2026 The Astrophysical Journal Letters 1005 .
Caption: Figure 13.
Top: inferred distributions of effective inspiral spin χeff in the correlated mass–spin BGP analysis. The solid lines give the median, while the shaded regions indicate the 90% credible intervals. In blue, we have the χeff distribution of BBH systems with at least one mass inside the 30−40 M⊙ peak range. In orange, we have the χeff distribution of BBH systems masses outside the 30−40 M⊙ peak range. While the two distributions are consistent within 90% credible intervals, systems outside the peak range appear to favor a distribution of χeff skewed toward more positive values. Meanwhile, systems inside the peak range appear to favor a more symmetrical distribution about χeff = 0. Middle: inferred distributions of primary mass from the correlated mass–spin BGP analysis. Bottom: inferred distributions of secondary mass from the correlated mass–spin BGP analysis. In both mass plots, blue shows the distribution for systems with small spins, χeff in the range ( − 0.05, 0.05), while orange shows the distribution for systems with larger spins, χeff in the range (0.1, 0.2). Note the preference for a higher proportion of mergers with masses ≈30 − 40 M⊙ for low spin systems (blue).
© 2026. The Author(s). Published by the American Astronomical Society.