We study the photodisintegration process triggered by the nonthermal electromagnetic Hawking radiation from primordial black holes (PBHs) in critical collapse model. We consider the simplest case that all PBHs formed at a single epoch stemming from an inflationary spectrum with a narrow peak, and an extended mass distribution is obtained due to critical phenomena of gravitational collapse. The presence of a low-mass tail of critical collapse mass function could lead to an enhancement of energetic photon emissions from Hawking radiation of PBHs. Nuclear photodisintegration rates are calculated with a nonthermal photon spectrum derived by solving the Boltzmann equation iteratively. The exact spectrum is much different than that based on an often-used analytical bended power-law spectrum and it is found to significantly depend on the adopted PBH mass functions. With the newest observational limit on the ³He abundance in Galactic H II regions, the updated ³He constraints on PBH mass spectrum in the horizon mass range 10¹²–10¹³ g are derived. Our results for the first time show that ³He constraints on the critical mass function are about one order of magnitude severer than the monochromatic one although the fraction of PBHs in the low-mass tail region is relatively small. The ⁶Li elemental abundance is also enhanced significantly for the critical mass function. More precise measurement of ⁶Li abundance is highly desirable to provide a promising constraint on PBHs in the future. For monochromatic mass function, we provide the analytical bounds for photodisintegration and hadrodissociation from PBH radiation, and we report discrepancies between our updated ³He constraints and the previous results.

我们研究了临界坍缩模型中原始黑洞 (PBH) 的非热电磁霍金辐射触发的光解体过程。我们考虑最简单的情况，即所有 PBH 形成于单个时期，源于具有窄峰的膨胀光谱，并且由于引力坍缩的临界现象而获得了扩展的质量分布。临界坍缩质量函数的低质量尾部的存在可能导致 PBH 的霍金辐射的高能光子发射增强。使用通过迭代求解 Boltzmann 方程得出的非热光子光谱计算核光解体率。确切的光谱与基于常用分析弯曲幂律光谱的光谱大不相同，并且发现它在很大程度上取决于采用的 PBH 质量函数。随着最新的观测极限³ He 丰度在银河 H II 区域，更新的³ He 约束对 PBH 质谱在视界质量范围 10 ¹² –10 ¹³ g 中得出。我们的结果首次表明，尽管低质量尾区中 PBH 的比例相对较小，但³ He 对临界质量函数的约束比单色约束严格一个数量级。临界质量函数的⁶ Li 元素丰度也显着提高。更精确的测量⁶Li 丰度非常需要为未来 PBH 提供有希望的约束。对于单色质量函数，我们提供了来自 PBH 辐射的光解离和强氢离解的分析界限，并报告了我们更新的³ He 约束与先前结果之间的差异。