第一代恒星和迷你类星体周围电离和加热的时间演化
Time-evolution of ionization and heating around first stars and miniquasars
摘要：
开发了一个一维辐射转移程序，用于跟踪第一批微类星体和第三星族星周围的电离和加热模式。该代码如下的氢和氦的物种的电离和星系际介质的温度分布作为红移的函数的演变。辐射转移计算表明，第一个迷你类星体和恒星的电离特征非常相似，但两者周围的加热模式却非常不同。此外，第一批大质量迷你类星体（~>10^5 M_{sun}）确实会在它们周围产生大的电离气泡，这些气泡有可能直接使用未来的射电望远镜成像。它还表明，电离的气泡不仅保持电离相当长的时间后，关闭的源，但继续扩大了一小段时间，由于二次碰撞促使其光谱的X射线部分。不同的光谱形状也产生了相当大的变化，电离分数和温度分布。我们还比较了辐射转移的结果与通常采用的分析近似加热的微型类星体，并发现，由于不充分的处理的He物种，分析的方法导致低估的温度在外半径的一个因素~5。第三族恒星-质量在10 - 1000 M_{sun}的范围内，并在50000 K的温度下模拟为黑体-被发现是有效的电离周围环境。在即将安装的LOFAR和SPT等射电和微波望远镜的背景下，还研究了对21厘米亮温的观测效应，即Sunyaev-Ze'ldovich热效应和动力学效应。
英文摘要：
A one dimensional radiative transfer code is developed to track the ionization and heating pattern around the first miniquasars and Population III stars. The code follows the evolution of the ionization of the species of hydrogen and helium and the intergalactic medium temperature profiles as a function of redshift. The radiative transfer calculations show that the ionization signature of the first miniquasars and stars is very similar yet the heating pattern around the two is very different. Furthermore, the first massive miniquasars (~>10^5 M_{sun}) do produce large ionized bubbles around them, which can potentially be imaged directly using future radio telescopes. It is also shown that the ionized bubbles not only stay ionized for considerable time after the switching off of the source, but continue to expand for a short while due to secondary collisions prompted by the X-ray part of their spectra. Varying spectral shapes also produced sizable variations in ionized fraction and temperature profile. We also compare the radiative transfer results with the analytical approximation usually adopted for heating by miniquasars and find that, because of the inadequate treatment of the He species, the analytical approach leads to an underestimation of the temperature in the outer radii by a factor ~5. Population III stars - with masses in the range of 10 - 1000 M_{sun} and modelled as blackbodies at a temperature of 50000 K - are found to be efficient in ionizing their surroundings. Observational effects on the 21 cm brightness temperature, the thermal and kinetic Sunyaev-Ze'ldovich effects, are also studied in the context of the upcoming radio and microwave telescopes like LOFAR and SPT.
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