论文标题
宇宙射线对宇宙黎明期间全局21厘米信号的影响
Impact of cosmic rays on the global 21-cm signal during cosmic dawn
论文作者
论文摘要
了解在早期宇宙中演变的半乳酸间介质（IgM）的热状态以研究宇宙黎明期间HI 21-CM信号的演变，这一点非常重要。在这里，我们考虑了早期流行III和POP II星的超新星产生的宇宙射线质子引起的IgM的加热。来自POP III超新星的低能宇宙射线质子可以从Minihalos逃脱，并通过碰撞和电离氢加热IgM。此外，在POP II超新星中产生的高能量质子可以逃脱宿主的光晕，并通过磁体alfvén波加热IgM。我们表明，由于这些宇宙射线颗粒引起的加热可以显着影响IGM温度，因此在$ z \ sim 14-18 $处的全局21-CM信号。 21厘米吸收曲线的深度，位置和持续时间高度取决于宇宙射线加热的效率。特别是，宇宙射线加热以及Lyman-$α$耦合以及我们认为实现“冷IGM背景”的暗物质 - 巴里昂相互作用可以很好地适合边缘信号。此外，我们认为，宇宙射线的特性和第一代恒星的性质可以通过准确测量宇宙黎明期间的全局21-CM吸收信号来限制。
It is extremely important to understand the processes through which the thermal state of the inter-galactic medium (IGM) evolved in the early universe in order to study the evolution of HI 21-cm signal during cosmic dawn. Here, we consider the heating of the IGM due to cosmic ray protons generated by the supernovae from both early Pop III and Pop II stars. The low energy cosmic ray protons from Pop III supernovae can escape from minihalos and heat the IGM via collision and ionization of hydrogen. Furthermore, high energy protons generated in Pop II supernovae can escape the hosting halos and heat the IGM via magnetosonic Alfvén waves. We show that the heating due to these cosmic ray particles can significantly impact the IGM temperature and hence the global 21-cm signal at $z\sim 14-18$. The depth, location, and duration of the 21-cm absorption profile are highly dependent on the efficiencies of cosmic ray heating. In particular, the EDGES signal can be well fitted by the cosmic ray heating along with the Lyman-$α$ coupling, and the dark matter-baryon interaction that we consider to achieve a `colder IGM background'. Further, we argue that the properties of cosmic rays and the nature of first generation of stars could be constrained by accurately measuring the global 21-cm absorption signal during the cosmic dawn.
