论文标题
流速度和Lyman-Werner辐射对第一颗恒星形成的影响
The influence of streaming velocities and Lyman-Werner radiation on the formation of the first stars
论文作者
论文摘要
宇宙中的第一颗恒星，即所谓的人口III星，形成了小小的暗物质，带有病毒温度$ t _ {\ rm vir} <10^{4} $ 〜k。在这些Minihaloes中的冷却以分子氢（H $ _ {2} $）为主，因此只有在形成足够h $ _ {2} $的小型halo中，人口III星形成才能在短时间内冷却。由于H $ _ {2} $冷却在更大的Minihaloes中更有效，因此有一个关键的Halo质量尺度$ M _ {\ rm min} $，以高于人口III星级形成，首先是可能的。两个重要的过程可以改变此最小质量尺度：相对于暗物质的流传输和H $ _ {2} $的光解离，高红移Lyman-Werner（LW）背景。在本文中，我们介绍了一组高分辨率宇宙学模拟的结果，这些模拟检查了这些过程对$ M _ {\ rm min} $以及$ M _ {\ rm Ave} $（单独和组合的Minihalo质量）的影响。我们表明，流对$ m _ {\ rm min} $的影响比LW背景更大，但两种效果都是加性的。我们还提供了拟合功能，以量化$ m _ {\ rm ave} $和$ m _ {\ rm min} $的依赖性在流速度和LW背景的强度上。
The first stars in the Universe, the so-called Population III stars, form in small dark matter minihaloes with virial temperatures $T_{\rm vir} < 10^{4}$~K. Cooling in these minihaloes is dominated by molecular hydrogen (H$_{2}$), and so Population III star formation is only possible in those minihaloes that form enough H$_{2}$ to cool on a short timescale. As H$_{2}$ cooling is more effective in more massive minihaloes, there is therefore a critical halo mass scale $M_{\rm min}$ above which Population III star formation first becomes possible. Two important processes can alter this minimum mass scale: streaming of baryons relative to the dark matter and the photodissociation of H$_{2}$ by a high redshift Lyman-Werner (LW) background. In this paper, we present results from a set of high resolution cosmological simulations that examine the impact of these processes on $M_{\rm min}$ and on $M_{\rm ave}$ (the average minihalo mass for star formation), both individually and in combination. We show that streaming has a bigger impact on $M_{\rm min}$ than the LW background, but also that both effects are additive. We also provide fitting functions quantifying the dependence of $M_{\rm ave}$ and $M_{\rm min}$ on the streaming velocity and the strength of the LW background.
