Does the math behind primordial black hole masses actually hold up?

Primordial black holes formed in the early universe are a dark matter candidate, but calculating how many form at each mass depends on subtle choices in the underlying statistics. Using excursion-set theory — a framework that tracks how density fluctuations look at different scales — the authors find that correlated noise changes the predicted low-mass tail of the black hole mass distribution compared to the widely-used Carr formula. The good news: Carr's formula stays reliable near the characteristic mass scale if you use a smooth filter in Fourier space.