AI 中文总结
研究早期宇宙恒星形成的突发性对21厘米宇宙黎明信号的影响，通过引入不等时相关性，利用Zeus21框架计算，发现其改变功率谱，在宇宙黎明开始时影响大，低红移其他地方可忽略。
AI 中文摘要
最近詹姆斯·韦布空间望远镜（JWST）的观测表明，早期宇宙中的恒星形成比标准模型假设的更具突发性。这种突发性可描述为一个随机过程，其特征是恒星形成时期的爆发幅度和相干时间。在本文中，我们研究了突发性恒星形成如何通过影响控制其演化的非局部辐射场（即莱曼-α和X射线背景）来改变宇宙黎明期间的21厘米功率谱。为此，我们在为这两个场提供源的恒星形成率密度中引入了不等时相关性，并使用公共代码Zeus21中实现的分析框架计算其影响。我们发现，由爆发性引起的时间相关性在莱曼-α和X射线场中产生了类似散粒噪声的贡献，增强了它们的自功率谱和交叉功率谱，同时使全局21厘米信号$T_{21}(z)$保持不变。结果，在宇宙黎明开始时，21厘米功率谱受到类似散粒噪声贡献的强烈修改，此时信号由较低质量的晕（$M_h\lesssim10^{10}\,M_\odot$）主导，并且在沃伊森-菲尔德吸收谷附近增强了几倍。在低红移的其他地方，聚类信号占主导地位且较大的晕驱动信号，爆发性成分可以忽略不计。
英文摘要
Recent JWST observations suggest that star formation in the early universe was substantially burstier than assumed in standard models. Such burstiness can be described as a stochastic process characterized by the burst amplitude and the coherence time of star formation epochs. In this paper, we investigate how bursty star formation modifies the 21-cm power spectrum during Cosmic Dawn through its impact on the non-local radiation fields that govern its evolution, namely Lyman-$α$ and X-ray backgrounds. To do so, we introduce an unequal-time correlation in the star-formation-rate density sourcing the two fields and we compute its impact using the analytical framework implemented in the public code Zeus21. We find that the burstiness-induced time correlation produces a shot-noise-like contribution in the Lyman-$α$ and X-ray fields, enhancing both their auto- and cross-power spectra while leaving the global 21-cm signal, $T_{21}(z)$, unchanged. As a result, the 21-cm power spectrum is strongly modified by a shot-noise-like contribution at the beginning of the Cosmic Dawn, where the signal is dominated by lower-mass halos ($M_h\lesssim10^{10}\,M_\odot$), and is boosted by a factor of a few near the Wouthuysen-Field absorption trough. Elsewhere at low redshift, where the clustering signal dominates and larger halos drive the signal, the burstiness component is negligible.
Comments21 pages, 8 figures, 1 table
