AI 中文总结
本研究提出次级微温暴胀可稀释热遗留物并增强小尺度扰动功率谱，产生近乎恒定的引力波背景和亚太阳质量原初黑洞，可解释NANOGrav信号并兼容暗物质组成。
AI 中文摘要
我们证明，在参数上远低于GUT能标的温度下发生的次级微温暴胀时期，不仅可以稀释再加热后形成的任何不想要的遗留热 relic，还能显著增强小尺度上原初曲率扰动的功率谱。后者在指数级大的共动尺度范围内近似标度不变，从而产生一个在宽频率范围内能量密度近乎恒定的随机引力波背景，以及相关的亚太阳质量原初黑洞（PBHs）族群。这一场景尤其可以解释NANOGrav信号，如果该信号在远高于截止频率$f_{max}$的频率上以相当量级持续存在的话。相关的PBH质量分布可能呈现峰值于质量$M_*\propto f_{max}^{-2}$，或在此质量阈值之上呈现宽平台，具体取决于谱倾斜。此外，在此场景中，NANOGrav信号与在小行星和行星质量范围内PBH构成暗物质的重要部分相容。
英文摘要
We show that a secondary period of warm inflation, at temperatures parametrically below the GUT scale, may not only dilute any unwanted thermal relics formed after reheating but also significantly enhance the power spectrum of primordial curvature perturbations on small scales. The latter is nearly scale-invariant over an exponentially large range of comoving scales, resulting in a stochastic gravitational wave background with a nearly constant energy density over a broad range of frequencies and an associated population of sub-solar mass primordial black holes (PBHs). This scenario could, in particular, explain the NANOGrav signal if it persists at much higher frequencies with a comparable magnitude, up to a sharp cut-off, $f_{max}$. The associated PBH mass distribution may exhibit either a peak at a mass $M_*\propto f_{max}^{-2}$ or a broad plateaux above this mass threshold, depending on the spectral tilt. Moreover, in this scenario the NANOGrav signal is compatible with a significant fraction of dark matter in PBHs in the asteroid- and planetary-mass ranges.
Comments7 pages, 2 figures
