论文标题
磁场对人口III星形成的影响
Impact of magnetic fields on Population III star formation
论文作者
论文摘要
宇宙中第一颗恒星形成的理论，即所谓的人口III（POP III），到目前为止，必须在很大程度上忽略了磁场的影响。与POP III星形成的磁融化（MHD）方面相辅相成，我们在这里进行了一系列理想化的数值实验，如果存在MHD效应，我们确定原始原始原始盘的片段化性能如何修饰。具体而言，从宇宙学初始条件开始，我们将重点放在Redshift $ Z \ SIM $ 25处的精选Minihalo中的中心区域上，在中间进化阶段插入磁场，并将其标准化为等级值的一部分。为了探索参数空间，我们考虑了不同的场几何形状，包括统一，径向，环形和多型磁场配置，而环形构型是最现实的。插入字段后，$ \ sim $ 8的密度$ \ sim $ \ sim的崩溃遵循，直到达到$ 10^{15} {\ rm \，cm}^{ - 3} $。我们发现磁场会导致气体崩溃的延迟。此外，环形场对塌陷的影响最大，因为它抑制了围绕中心核心的新出现的盘子的碎裂，并导致形成更大的核心。因此，对流行恒星的形成及其质量分布的完全理解需要考虑到磁场的影响。我们进一步得出结论，理想的MHD只是这项努力的第一步，需要对耗散效应（例如双极扩散和欧姆消耗）进行全面处理。
The theory of the formation of the first stars in the Universe, the so-called Population III (Pop III), has until now largely neglected the impact of magnetic fields. Complementing a series of recent studies of the magneto-hydrodynamic (MHD) aspects of Pop III star formation, we here carry out a suite of idealized numerical experiments where we ascertain how the fragmentation properties of primordial protostellar discs are modified if MHD effects are present. Specifically, starting from cosmological initial conditions, we focus on the central region in a select minihalo at redshift $z\sim$ 25, inserting a magnetic field at an intermediate evolutionary stage, normalized to a fraction of the equipartition value. To explore parameter space, we consider different field geometries, including uniform, radial, toroidal, and poloidal field configurations, with the toroidal configuration being the most realistic. The collapse of the gas is followed for $\sim$8 orders of magnitude in density after the field was inserted, until a maximum of $10^{15}{\rm \,cm}^{-3}$ is reached. We find that the magnetic field leads to a delay in the collapse of the gas. Moreover, the toroidal field has the strongest effect on the collapse as it inhibits the fragmentation of the emerging disc surrounding the central core and leads to the formation of a more massive core. The full understanding of the formation of Pop~III stars and their mass distribution thus needs to take into account the effect of magnetic fields. We further conclude that ideal MHD is only a first step in this endeavor, to be followed-up with a comprehensive treatment of dissipative effects, such as ambipolar diffusion and Ohmic dissipation.
