星族III恒星形成中HII区的捕获
Trapping of HII regions in Population III star formation
摘要：
来自大质量第三星族（Pop III）恒星的辐射反馈以电离和光解离光子的形式被广泛认为在关闭这些恒星的吸积方面发挥着核心作用。了解这是否以及如何发生对于预测这些恒星达到的最终质量以及Pop III恒星初始质量函数的形式至关重要。为了帮助我们更好地了解大质量Pop III恒星的紫外线辐射对周围气体的影响，我们进行了高分辨率的模拟这些恒星的形成和早期演化，使用AREPO移动网格代码加上创新的辐射转移模块SPRAI。与大多数以前的结果相反，我们发现，这些恒星的电离辐射被困在密集的吸积盘周围。因此，包括辐射反馈没有显着的影响，无论是数量或总质量的原恒星形成在20 kyr期间，我们模拟。我们表明，我们得到定性不同的结果，从以前的研究波普III恒星反馈的原因在于如何将辐射注入模拟。只有当光子注入的尺度小于吸积盘的局部尺度高度时，才会发生HII区域捕获，这一标准在以前的3D模拟中没有得到满足。最后，我们推测是否外流驱动的磁场或莱曼α辐射压力可能能够清除足够的气体远离恒星，让HII区逃离磁盘。
英文摘要：
Radiative feedback from massive Population III (Pop III) stars in the form of ionising and photodissociating photons is widely believed to play a central role in shutting off accretion onto these stars. Understanding whether and how this occurs is vital for predicting the final masses reached by these stars and the form of the Pop III stellar initial mass function. To help us better understand the impact of UV radiation from massive Pop III stars on the gas surrounding them, we carry out high resolution simulations of the formation and early evolution of these stars, using the AREPO moving-mesh code coupled with the innovative radiative transfer module SPRAI. Contrary to most previous results, we find that the ionising radiation from these stars is trapped in the dense accretion disk surrounding them. Consequently, the inclusion of radiative feedback has no significant impact on either the number or the total mass of protostars formed during the 20 kyr period that we simulate. We show that the reason that we obtain qualitatively different results from previous studies of Pop III stellar feedback lies in how the radiation is injected into the simulation. HII region trapping only occurs if the photons are injected on scales smaller than the local scale height of the accretion disk, a criterion not fulfilled in previous 3D simulations of this process. Finally, we speculate as to whether outflows driven by the magnetic field or by Lyman-alpha radiation pressure may be able to clear enough gas away from the star to allow the HII region to escape from the disk.
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