The rich complexity of 21-cm fluctuations produced by the first stars
The rich complexity of 21-cm fluctuations produced by the first stars
复制标题
第一批恒星产生的 21 厘米涨落的丰富复杂性
DOI：
10.1093/mnras/stu1744
复制
发表时间：
2014
影响因子：
4.8
通讯作者：
T. University
中科院分区：
文献类型：
--
作者：
A. Fialkov;R. B. E. N. Superieure;París;T. University
我们探索了红移范围z=7-40的21厘米信号的完整历史。这个红移范围包括与原始恒星形成有关的宇宙演化的各个时期，应该可以由现有的或计划中的低频射电望远镜访问。我们用半数值计算方法研究了Ly-α、X射线、Lyman-Werner和电离辐射的非均匀背景下，在0.03到1 Mpc的波数范围内的涨落信号。我们关注最近注意到的由高质量X射线双星的硬X射线光谱主导的加热预期。我们研究了由此产生的延迟的宇宙加热和气体温度波动的抑制，允许促成恒星形成的最小晕质量的巨大变化。我们发现，在观测中探测到加热峰值的波数应该告诉我们发射的光子的特征平均自由程和光谱，从而给出关于加热原始宇宙的源的特征的关键线索。我们还考虑了视线各向异性，它允许从21厘米的信号中提取额外的信息。例如，宇宙气体被加热到宇宙微波背景温度的加热转变应该用一个特别各向同性的功率谱清楚地标记出来。更广泛地说，一个额外的交叉功率分量$P_X$直接探测主导21厘米波动的来源。特别是，在宇宙再电离期间(以及在刚才提到的加热相变之后)，$P_X$在以电离涨落为主的标度上为负，在以温度涨落为主的标度上为正。
We explore the complete history of the 21-cm signal in the redshift range z = 7-40. This redshift range includes various epochs of cosmic evolution related to primordial star formation, and should be accessible to existing or planned low-frequency radio telescopes. We use semi-numerical computational methods to explore the fluctuation signal over wavenumbers between 0.03 and 1 Mpc$^{-1}$, accounting for the inhomogeneous backgrounds of Ly-$\alpha$, X-ray, Lyman-Werner and ionizing radiation. We focus on the recently noted expectation of heating dominated by a hard X-ray spectrum from high-mass X-ray binaries. We study the resulting delayed cosmic heating and suppression of gas temperature fluctuations, allowing for large variations in the minimum halo mass that contributes to star formation. We show that the wavenumbers at which the heating peak is detected in observations should tell us about the characteristic mean free path and spectrum of the emitted photons, thus giving key clues as to the character of the sources that heated the primordial Universe. We also consider the line-of-sight anisotropy, which allows additional information to be extracted from the 21-cm signal. For example, the heating transition at which the cosmic gas is heated to the temperature of the cosmic microwave background should be clearly marked by an especially isotropic power spectrum. More generally, an additional cross-power component $P_X$ directly probes which sources dominate 21-cm fluctuations. In particular, during cosmic reionization (and after the just-mentioned heating transition), $P_X$ is negative on scales dominated by ionization fluctuations and positive on those dominated by temperature fluctuations.
影响因子：
6.5
作者：
van Haarlem, M. P.;Wise, M. W.;van Zwieten, J.
通讯作者：
van Zwieten, J.