Nuclear Reaction Defines the Abyss for Black Holes ⚡ экспресс
The fusion reaction of carbon and helium in stellar cores determines how a star dies and what mass black hole it leaves behind. Gravitational waves have revealed a 'gap' in black hole masses, but its boundaries strongly depend on theoretical assumptions. A new analysis of nuclear data (the ^12C(α,γ)^16O reaction) narrowed the energy dependence of its probability (the S-factor at 300 keV) and showed that the reaction proceeds more slowly than some interpretations allowed. As a result, the lower edge of the gap shifts upward—black holes from single stars must be no lighter than 61–75 solar masses.
Gravitational waves have laid bare an abyss: black holes with masses between 60 and 120 Suns are almost never born. This chasm is carved out by pair-instability supernovae—explosions that leave not even a speck of the star. Whether the star falls into the abyss or survives on its edge depends on the reaction of carbon with helium, which governs the core composition.
This process is leisurely: even a tiny speedup would turn all carbon into oxygen, depriving the universe of life. Fred Hoyle first realized the reaction is tuned exquisitely finely, otherwise carbon would be hundreds of times scarcer. New data have narrowed the possible rates by nearly half. It turns out the edge of the abyss lies farther out than thought: the lightest ordinary black holes start at 61–75 solar masses. A shift of just a couple percent—and the boundary leaps by tens of masses.
🎯 The carbon-helium reaction is so slow that the slightest acceleration would deprive the universe of carbon-based life.