Image Details
GWTC-4.0: Population Properties of Merging Compact Binaries
A. G. Abac et al 2026 The Astrophysical Journal Letters 1005 .
Caption: Figure 21.
First row: marginal χeff distributions with BGP (blue) and B-SPLINE (green) models, as compared to the SKEW-NORMAL EFFECTIVE SPIN (red-orange), GAUSSIAN EFFECTIVE SPINS (purple), and (q, χeff) SPLINE (maroon) models. The PPD (average) is shown with a dark line, and the 90% confidence intervals are shaded. Second and third rows: posteriors on the first percentile of the χeff distribution (upper left), the fraction of χeff < 0 (upper right), HM fraction (lower left), and the skew (lower right). See Section 6.3.2 for a discussion of these quantities. Colors correspond to the top panel; purple dashed is GWTC-3.0 with the GAUSSIAN EFFECTIVE SPINS model for comparison.
© 2026. The Author(s). Published by the American Astronomical Society.