Signatures of cosmic ray heating in 21-cm observables
Signatures of cosmic ray heating in 21-cm observables
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21 厘米可观测物体中宇宙射线加热的特征
DOI：
10.1093/mnras/stad3014
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发表时间：
2023
影响因子：
4.8
通讯作者：
Gessey-Jones T
中科院分区：
文献类型：
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作者：
Gessey-Jones T
超新星产生的宇宙射线带走了其母恒星一生能量发射的很大一部分，使其成为加热早期宇宙星际介质(IGM)的合理机制。在回顾了关于宇宙线加热的现有文献之后，我们开发了一个用于模拟21厘米信号的三维半数值模拟的这种加热机制的灵活模型，并首次研究了它在21厘米功率谱和断层图上留下的印记。我们发现，IGM的宇宙射线加热是短程的，导致加热聚集在恒星形成地点周围，并在21厘米发射的受热区和未受热的吸收区域之间形成鲜明对比。与已发现的X射线加热相比，这种对比导致宇宙射线加热情况下的小尺度能量更大，从而提出了一种用未来21厘米的观测来测试IGM加热性质的方法。最后，我们发现，在宇宙射线只能有效地逃离低质量光晕的模型中，我们发现了出人意料的丰富的热历史，例如在这些高能粒子来自第三族恒星超新星残骸的情况下。在这些模式中，加热和Lyman-Werner反馈的相互作用可以在IGM动力学温度中产生局部峰值，并且在有限的参数范围内，在全球21厘米信号中产生平坦的吸收槽。
Cosmic rays generated by supernovae carry away a significant portion of the lifetime energy emission of their parent star, making them a plausible mechanism for heating the early universe intergalactic medium (IGM). Following a review of the existing literature on cosmic ray heating, we develop a flexible model of this heating mechanism for use in 3D seminumerical 21-cm signal simulations and conduct the first investigations of the signatures it imprints on the 21-cm power spectrum and tomographic maps. We find that cosmic ray heating of the IGM is short-ranged, leading to heating clustered around star-forming sites, and a sharp contrast between heated regions of 21-cm emission and unheated regions of absorption. This contrast results in greater small-scale power for cosmic ray heated scenarios compared to what is found for X-ray heating, thus suggesting a way to test the nature of IGM heating with future 21-cm observations. Finally, we find an unexpectedly rich thermal history in models where cosmic rays can only escape efficiently from low-mass haloes, such as in scenarios where these energetic particles originate from population III star supernovae remnants. The interplay of heating and the Lyman–Werner feedback in these models can produce a local peak in the IGM kinetic temperature and, for a limited parameter range, a flattened absorption trough in the global 21-cm signal.