SPATIALLY EXTENDED 21 cm SIGNAL FROM STRONGLY CLUSTERED UV AND X-RAY SOURCES IN THE EARLY UNIVERSE
SPATIALLY EXTENDED 21 cm SIGNAL FROM STRONGLY CLUSTERED UV AND X-RAY SOURCES IN THE EARLY UNIVERSE
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来自早期宇宙中强簇状紫外线和 X 射线源的空间延伸 21 厘米信号
DOI：
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
J. Wise
中科院分区：
文献类型：
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作者：
K. Ahn;Haoting Xu;M. Norman;M. Alvarez;J. Wise
通过对早期宇宙中星族III（PopIII）和II（PopII）天体形成和辐射反馈的数值模拟，给出了对一组强聚集源的局部21 cm差分亮温（δTb）的预测。这些天体位于一个高度偏置的环境中，这是一个罕见的高密度峰（“Rarepeak”），延伸到1.77 Mpc。我们研究了紫外线和X射线光子对星系际介质（IGM）和由此产生的δTb的影响，当Pop III星被假设为通过非常有效地形成X射线双星来发射X射线光子时。我们参数化了X射线光子的静止坐标系光谱能量分布，它调节了X射线光子俘获、IGM加热、次级Lyα泵浦以及由此产生的δTb形态。发射区（δTb > 0）和吸收区（δTb < 0）的组合出现在不同的振幅和角标度。高密度环境对信号的增强（δ = 0.64）和相对较大的尺度相结合，使Rarepeak成为一个可辨别的，空间延伸（θ = 10′）的物体，在13 ° z 17的21厘米观测，这是发现可检测的作为一个单一的目标与SKA的积分时间为1000小时。功率谱分析的一些SKA的前体（低频阵列，Murchison宽场阵列，探测再电离时期的精密阵列）的这些罕见的峰值被发现是困难的，由于这些峰值的稀有性，和贡献只有这些罕见的峰值总功率谱仍然次占主导地位相比，所有天体物理源。
We present our prediction for the local 21 cm differential brightness temperature (δTb) from a set of strongly clustered sources of Population III (Pop III) and II (Pop II) objects in the early universe, by a numerical simulation of their formation and radiative feedback. These objects are located inside a highly biased environment, which is a rare, high-density peak (“Rarepeak”) extending to ∼7 comoving Mpc. We study the impact of ultraviolet and X-ray photons on the intergalactic medium (IGM) and the resulting δTb, when Pop III stars are assumed to emit X-ray photons by forming X-ray binaries very efficiently. We parameterize the rest-frame spectral energy distribution of X-ray photons, which regulates X-ray photon-trapping, IGM-heating, secondary Lyα pumping and the resulting morphology of δTb. A combination of emission (δTb > 0) and absorption (δTb < 0) regions appears in varying amplitudes and angular scales. The boost of the signal by the high-density environment (δ ∼ 0.64) and on a relatively large scale combines to make Rarepeak a discernible, spatially extended (θ ∼ 10′) object for 21 cm observation at 13 ≲ z ≲ 17, which is found to be detectable as a single object by SKA with integration time of ∼1000 hr. Power spectrum analysis by some of the SKA precursors (Low Frequency Array, Murchison Widefield Array, Precision Array for Probing the Epoch of Reionization) of such rare peaks is found to be difficult due to the rarity of these peaks, and the contribution only by these rare peaks to the total power spectrum remains subdominant compared to that by all astrophysical sources.
DOI：
10.1088/2041-8205/756/1/l16
发表时间：
2012-06
期刊：
The Astrophysical Journal Letters
影响因子：
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作者：
K. Ahn;I. Iliev;P. Shapiro;G. Mellema;J. Koda;Y. Mao
通讯作者：
K. Ahn;I. Iliev;P. Shapiro;G. Mellema;J. Koda;Y. Mao