Gravitational-wave constraints on the pair-instability mass gap and nuclear burning in massive stars
引力波对成对不稳定性质量间隙和大质量恒星核燃烧的限制
Pair instability should prevent the direct formation of black holes above about 50 M<SUB>☉</SUB>, creating a `pair-instability' mass gap. Yet gravitational-wave observations have detected black holes in this mass range. These systems can be explained with uncertainties in massive-star evolution, or hierarchical mergers in stellar clusters, which are expected to produce large spins with isotropic orientations. Here we present evidence for the pair-instability mass gap in the LIGO-Virgo-KAGRA fourth transient catalogue, with a lower edge at 44 .3<SUB>-3.5</SUB><SUP>+5.9</SUP>M<SUB>☉</SUB>. We also obtain a measurement of the <SUP>12</SUP>C(α, γ)<SUP>16</SUP>O reaction rate, yielding an S-factor of 26 8<SUB>-116</SUB><SUP>+195</SUP>keV b, a parameter critical for modelling helium burning and stellar evolution. The data reveal two populations: a low-spin group with no black holes above the gap, and a high-spin, isotropic group that extends across the full mass range and occupies the gap, consistent with hierarchical mergers. These findings are consistent with pair instability playing a role in shaping the black hole mass spectrum, point to a connection between gravitational-wave astronomy and nuclear astrophysics, and highlight dense stellar clusters as key environments in the growth of black holes.
展开 ▾首次通过引力波数据约束了 12C(α,γ)16O 反应率(S300=268 keV b),为核天体物理提供全新诊断手段;发现低自旋黑洞群体在 ~45 M⊙ 处截断而高自旋群体占据间隙,强烈支持星团分级并合图像。
针对黑洞质量谱中是否存在因正负电子对不稳定性导致的‘质量间隙’,以往基于 GWTC-3 的搜寻未能给出定论(Edelman+ 2021)。本研究利用更大样本的 GWTC-4 数据,通过非参数自旋分布分析,首次以超过 10^4 的贝叶斯因子确认低自旋黑洞群体在 ~44 M⊙ 处截断,与理论预言的 PISN 间隙下缘一致(Farmer+ 2019);高出该质量的黑洞则呈现宽、近各向同性的自旋分布,与密集星团中分级并合的预期相吻合(Antonini+ 2025)。基于此,作者将测得的间隙下缘转化为对 12C(α,γ)16O 反应率的约束,为核天体物理提供了独立于实验室的天体物理探针,所得 S 因子与近期实验结果相符(Farmer+ 2020)。这一交叉不仅首次架起了引力波与核燃烧速率的桥梁,还预示着随着未来观测的积累,可望更精确地限定大质量恒星演化中的关键核参数,并量化不同星团环境对黑洞质量谱的贡献,从而全面追踪从恒星坍缩到宇宙化学元素合成的链条。
预印本 2025-09-04 · 接收 2026-03-26 · 刊出 2026-05-07 · 收录 2026-07-28