标题： 在暗时代全球21厘米信号背景下重新审视超导宇宙弦的约束 显示英文标题

标题： Revisiting constraints on superconducting cosmic strings in light of Dark Ages global 21-cm signal

摘要： 超导宇宙弦（SCS）是宇宙弦的一种特殊情况，其核心携带带电场。 当SCS穿过磁化区域时，弦中的带电粒子会受到洛伦兹力的作用，这可以在整个电磁波谱上产生辐射。 这种辐射可以将能量注入周围的等离子体，从而改变星际介质（IGM）的热演化和电离演化，进而影响全球21厘米信号。 SCS在再结合时期后的特征主要在低频（无线电）范围内进行研究，这不会影响IGM的状态。 在本工作中，我们研究了衰减的SCS对黑暗时代全球21厘米信号$(\delta T_b)$的影响，同时考虑了电离辐射和无线电辐射。 在没有重子结构形成的情况下，宇宙在这一时期主要是均匀的，因此黑暗时代的信号可以提供不受天体物理不确定性影响的原始宇宙学信息。 考虑到在红移$z\sim 89$时，从$\Lambda \rm CDM$框架到$5\,\rm mK$和$15\,\rm mK$的$\delta T_b$的变化，我们推导出宇宙弦的环电流$I\gtrsim 11.5\,\rm GeV$和弦张力$G\mu_s\gtrsim 2.5\times 10^{-15}$的上限。 显示英文摘要

摘要： The Superconducting Cosmic Strings (SCS) are a special case of cosmic strings that have a core carrying a charged field. When SCS pass through magnetized regions, the charged particles in the string experience a Lorentz force, which can produce radiation on the entire electromagnetic spectrum. This radiation can inject energy into the surrounding plasma, resulting in a modification of the thermal and ionization evolution of the intergalactic medium (IGM) and, subsequently, the global 21-cm signal. The signatures of SCS in the post-recombination era have been primarily studied in the low-frequency (radio) regime, which does not impact the state of the IGM. In this work, we study the effect of decaying SCS on the Dark Ages global 21-cm signal $(\delta T_b)$, considering both the ionizing and radio radiations. The Dark Ages signal can provide pristine cosmological information free from astrophysical uncertainties, as the universe was primarily homogeneous during this era in the absence of baryonic structure formation. Considering a change in the $\delta T_b$ at redshift $z\sim 89$ from the $\Lambda \rm CDM$ framework to be $5\,\rm mK$ and $15\,\rm mK$, we derive an upper bound on the loop current of cosmic string, $I\gtrsim 11.5\,\rm GeV$, and string tension, $G\mu_s\gtrsim 2.5\times 10^{-15}$.