AI 中文总结
该研究基于大尺度白噪声框架推导引力波诱导的大尺度白噪声振幅，将其观测未探测结果转化为对引力波产生红移和密度的新约束，排除了近期脉冲星计时阵列探测到的引力波在z*~10^8前存在的可能。
AI 中文摘要
随机引力波（GW）背景会在宇宙流体的流动中产生切变，该切变通过非线性模式耦合在曲率密度场中生成大尺度白噪声（LSWN）。基于作者前期工作的LSWN框架，推导了这种GW诱导LSWN的振幅，并将LSWN的观测未探测结果转化为对引力波产生红移和密度的约束。具体而言，对于在红移z*处产生、频率带为f*、z=0时的密度参数为Ω_GW0^*的引力波，其必须满足z_*^2·Ω_GW0^*<5×10^7·(f_*/nHz)^(3/2)的最小约束。例如，该约束排除了脉冲星计时阵列最近探测到的引力波[参考文献：NANOGrav:2023hvm]出现在z*~10^8之前的可能，而该时间远晚于夸克强子相变时期。尽管该约束比其他引力波约束强几个数量级，但它是LSWN的最小约束，因为对早期宇宙引力波产生的实际建模（包括引力波源的离散性以及相关声波产生的LSWN）可能会将该约束再收紧几个数量级。
英文摘要
A stochastic gravitational wave (GW) background sources a shear in the flow of cosmic fluid which, through non-linear mode coupling, generates large-scale white noise (LSWN) in the kurvature density field. Building on the LSWN framework of our previous work, we derive the amplitude of this GW-induced LSWN and translate the observational non-detection of LSWN into bounds on the production redshift and density of gravity waves. In particular, a minimal constraint on gravity waves with $z=0$ density parameter $Ω_\mathrm{GW0}^*$ in frequency band $f_*$ generated at redshift $z_*$ must satisfy ${z_*}^2\,Ω_\mathrm{GW0}^*<5\times10^7\,(f_*/\mathrm{nHz})^{3/2}$. This, for example, precludes the gravity waves recently detected by pulsar timing arrays \cite{NANOGrav:2023hvm} from being present before $z_*\sim10^8$, long after the quark hadron phase transition. While orders of magnitude stronger than other constraints on gravity waves, this is a minimal LSWN constraint as realistic modeling of early universe gravity wave production, including the granularity of the gravity-wave sources and the LSWN produced by the associated acoustic waves would probably tighten this constraint by orders of magnitude.
Comments16 pages 2 figures
