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arXiv · 2605.05300

No model-independent evidence for a peak in binary black hole spin (mis)alignments

Noah E. Wolfe·Salvatore Vitale·Michael Zevin
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Abstract

The degree of black-hole spin-orbit misalignment ("tilts") in the astrophysical population could be a powerful diagnostic to distinguish between binary formation in isolation, in dynamical environments, or in hierarchical triples. However, robust population-level spin tilt measurements are complicated by model misspecification as well as numerical and Poisson variance, ultimately owing to poor single-event constraints on tilts. Motivated by reports of a possible peak in the spin tilt distribution, we analyze the fourth LIGO-Virgo-KAGRA gravitational-wave transient catalog to test for preferred spin orientations at different black hole masses. We find that a peak in spin tilts is not statistically significant nor model independent. Since the data cannot be used to reliably identify subpopulations based on their spin tilt properties, we also consider a complementary approach: measuring the spin magnitude and tilt distributions at fixed mass scales. We find no confident correlation between mass and spin tilt, but we do confirm a confident correlation between spin magnitude and mass, corroborating recent analyses.

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Noah E. Wolfe, Salvatore Vitale, Michael Zevin. 2026-05-06. No model-independent evidence for a peak in binary black hole spin (mis)alignments. https://doi.org/10.3847/2041-8213%2Fae90ae

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