论文标题
为半数字模拟建模人口III星星
Modelling Population III stars for semi-numerical simulations
论文作者
论文摘要
从理论上对由人口III星（POP III星）引起的21-CM信号进行建模是从当前和即将到来的21-CM观测值中提取流行III星的富有成果信息的关键。在这项工作中，我们开发了一个新的流行III星模块，其中电离光子和Lyman-Werner（LW）光子的逃生部分，紫外线辐射的照相加热以及LW反馈始终合并。通过将模块实施到公共21 cm半数仿真代码，21cmfast，我们演示了21 cm信号计算并研究了POP III Star建模的重要性。我们发现，从流行III恒星对宇宙电离的贡献显着取决于逃生部分的处理。借助我们的逃生分数模型，Pop III恒星几乎没有促进电源的贡献，因为较高的逃逸分数较高的巨大光环不足，因此由于LW的反馈而无法托管Pop III恒星。另一方面，Pop III恒星很好地促进了与常规的恒定逃生部分的电源。我们还发现，如果宇宙的电离分数高于大约1％，则紫外线加热对21 cm全球信号和21 cm功率谱的影响不高。在这种情况下，21 cm全局信号的强度取决于光加热效率，因此取决于流行III星级质量。我们得出的结论是，必须准确预测21厘米可观察到将来的观察结果的详细建模。
Theoretically modelling the 21-cm signals caused by Population III stars (Pop III stars) is the key to extracting fruitful information on Pop III stars from current and forthcoming 21-cm observations. In this work we develop a new module of Pop III stars in which the escape fractions of ionizing photons and Lyman-Werner (LW) photons, photo-heating by UV radiation, and LW feedback are consistently incorporated. By implementing the module into a public 21-cm semi-numerical simulation code, 21CMFAST, we demonstrate 21-cm signal calculations and investigate the importance of Pop III star modelling. What we find is that the contribution from Pop III stars to cosmic reionization significantly depends on the treatment of the escape fraction. With our escape fraction model, Pop III stars hardly contribute to reionization because less massive halos, whose escape fraction are high, cannot host Pop III stars due to LW feedback. On the other hand, Pop III stars well contribute to reionization with the conventional constant escape fraction. We also find that UV photo-heating has non-negligible impact on the 21-cm global signal and the 21-cm power spectrum if the ionization fraction of the Universe is higher than roughly 1 percent. In this case, the strength of the 21-cm global signal depends on the photo-heating efficiency and thus on the Pop III star mass. We conclude that detailed modelling of Pop III stars is imperative to predict 21-cm observables accurately for future observations.
