AI 中文总结
该研究采用CVOS模型计算超导宇宙弦的SGWB，发现黑暗时代21厘米信号可约束其参数空间，排除大量可行参数，凸显月球21厘米实验与引力波观测台的互补性。
AI 中文摘要
超导宇宙弦（SCSs）具有三个参数：无量纲弦张力$G\boldsymbol{\u03bc}$、电流振幅$Y$和矢量耦合$\tilde{e}$，这是近期研究中探讨的内容。我们采用电荷速度依赖的单尺度（CVOS）模型，计算载流回路发出的随机引力波背景（SGWB），其中包含矢量辐射的抑制效应。尽管此前研究表明，较大的$\tilde{e}$会抑制SGWB，从而允许更大的$G\boldsymbol{\u03bc}$规避脉冲星计时阵列（PTA）的约束，但我们证明，该参数空间会被一个独立的、天体物理上干净的探针——黑暗时代全局21厘米信号明确约束。我们将近期得到的21厘米约束重新计算到通用的$(\tilde{e},Y,G\boldsymbol{\u03bc})$参数空间中，发现在矢量辐射发射开始主导的阈值处，任何耦合$\tilde{e}\boldsymbol{\u2273}10^{-7}$、$Y\boldsymbol{\u2243}0.67$且$G\boldsymbol{\u03bc}\boldsymbol{\u2273}10^{-13}$的情况，会注入足够的电离辐射，完全消除红移$z\boldsymbol{\u2243}89$处的21厘米吸收信号。更大的电流振幅会施加更严格的约束，这排除了大量被认为可行的参数空间。我们与模型无关的结果凸显了未来基于月球的21厘米实验与引力波（GW）观测台之间的互补性。
英文摘要
Superconducting cosmic strings (SCSs) are characterized by three parameters: the dimensionless string tension $Gμ$, the current amplitude $Y$, and the vector coupling, $\tilde{e}$ as recently explored in \cite{Rybak:2024our}. Using the Charge-Velocity-dependent One-Scale (CVOS) model, we compute the stochastic gravitational wave background (SGWB) emitted by current-carrying loops, including the suppression effect of vector radiation. While previous studies have shown that large $\tilde{e}$ suppresses the SGWB, allowing larger $Gμ$ to evade pulsar timing array (PTA) bounds \cite{Rybak:2024our}, we demonstrate that this parameter space is definitively constrained by an independent, astrophysically clean probe: the Dark Ages global $21$-cm signal. We recalculated the recently derived $21$-cm bounds \cite{Si:2025vsj} into the generic $(\tilde{e},Y,Gμ)$ parameter space and find that at the threshold where vector radiation emission starts dominating, any coupling $\tilde{e}\gtrsim 10^{-7}$ and $Y\simeq 0.67$ and $Gμ\gtrsim 10^{-13}$ injects sufficient ionizing radiation to completely erase the $21$-cm absorption signal at redshift $z\simeq89$. Greater current amplitudes impose more stringent constraints. This excludes a large parameter space considered viable. Our model-independent results highlight the complementarity between future lunar-based $21$-cm experiments and gravitational wave (GW) observatories.
Comments9+2 pages, 3 figures
