Title: From dark matter halos to pre-stellar cores: High resolution follow-up of cosmological Lyman-Werner simulations Show Chinese title

Title: 从暗物质晕到分子云核：宇宙学Lyman-Werner模拟的高分辨率后续研究

Abstract: Molecular hydrogen allows cooling in primordial gas, facilitating its collapse into Population III stars within primordial halos. Lyman-Werner (LW) radiation from these stars can escape the halo and delay further star formation by destroying H$_2$ in other halos. As cosmological simulations show that increasing the background LW field strength increases the average halo mass required for star formation, we perform follow-up simulations of selected halos to investigate the knock-on effects this has on the Population III IMF. We follow 5 halos for each of the $J_{21}$ = 0, 0.01 and 0.1 LW field strengths, resolving the pre-stellar core density of $10^{-6}$ g cm$^{-3}$ (10$^{18}$ cm$^{-3}$) before inserting sink particles and following the fragmentation behaviour for hundreds of years further. We find that the mass accreted onto sinks by the end of the simulations is proportional to the mass within the $\sim 10^{-2}$ pc molecular core, which is not correlated to the initial mass of the halo. As such, the IMFs for masses above the brown dwarf limit show little dependence on the LW strength, although they do show variance in the number of low-mass clumps formed. As the range of background LW field strengths tested here covers the most likely values from literature, we conclude that the IMF for so-called Pop III.2 stars is not significantly different from the initial population of Pop III.1 stars. The primordial IMF therefore likely remains unchanged until the formation of the next generation of Population II stars. Show Chinese abstract

Abstract: 分子氢允许原始气体冷却，促进其坍缩形成第三星族恒星。这些恒星发出的莱曼-瓦纳辐射可以逃离晕星团并破坏其他晕星团中的H$_2$，从而延迟进一步的恒星形成。正如宇宙学模拟所示，增加背景莱曼-瓦纳场强度会提高恒星形成的平均晕星团质量。我们对选定的晕星团进行了后续模拟，以研究这对第三星族初始质量函数（IMF）产生的连锁效应。我们分别对$J_{21}$=0、0.01和0.1的莱曼-瓦纳场强度下的5个晕星团进行追踪，解析出预恒星核密度为$10^{-6}$g cm$^{-3}$（10$^{18}$cm$^{-3}$）之前插入汇粒子并继续追踪数百年的碎裂行为。我们发现，到模拟结束时沉降粒子上积累的质量与分子核$\sim 10^{-2}$pc内的质量成正比，而该质量与晕星团的初始质量无关。因此，超过褐矮星极限的质量的IMF对莱曼-瓦纳场强度几乎没有依赖性，尽管它们确实显示出形成低质量团块数量的变化。由于这里测试的背景莱曼-瓦纳场强度范围涵盖了文献中最可能的值，我们得出结论，所谓的第三星族.2恒星的IMF与最初的第三星族.1恒星群体没有显著差异。因此，原始的IMF很可能在下一代第二星族恒星形成之前保持不变。