The EDGES collaboration’s observation of an anomalously strong 21 cm absorption feature around the cosmic dawn era has energised the cosmological community by suggesting a novel signature of dark matter in the cooling of cosmic hydrogen. In a recent paper, we have argued that by virtue of the ability to mediate cooling processes whilst in the condensed phase, a small amount of axion dark matter can explain these observations within the context of Standard Models of axions and axion-like particles. These axions and axion-like particles (ALPs) can thermalise through gravitational self-interactions and so eventually form a Bose–Einstein condensate (BEC), whereupon large-scale long-range correlation can produce experimentally observable signals such as these. In this context, the EDGES best-fit result favours an ALP mass in the (6, 400) meV range. Future experiments and galaxy surveys, particularly the International Axion Observatory (IAXO) and EUCLID, should have the capability to directly test this scenario. In this paper, we will explore this mechanism in detail and give more thorough computational details of certain key points.

中文翻译：

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EDGES 21cm吸收异常和轴子诱导冷却的详细探索

EDGES 合作对宇宙黎明时代周围异常强烈的 21 厘米吸收特征的观察通过提出暗物质在宇宙氢冷却中的新特征，为宇宙学界注入了活力。在最近的一篇论文中，我们认为，凭借在凝聚相中调节冷却过程的能力，少量的轴子暗物质可以在轴子和类轴子粒子的标准模型的背景下解释这些观察结果。这些轴子和类轴子粒子（ALPs）可以通过引力自相互作用热化，最终形成玻色-爱因斯坦凝聚体（BEC），从而大规模的长程相关可以产生诸如此类的实验可观察信号。在这种情况下，EDGES 最佳拟合结果有利于 (6, 400) meV 范围内的 ALP 质量。未来的实验和星系调查，特别是国际轴子天文台 (IAXO) 和 EUCLID，应该有能力直接测试这种情况。在本文中，我们将详细探讨这种机制，并对某些关键点给出更彻底的计算细节。