论文标题
与当前时期相比
The statistical properties of stars at redshift, z=5, compared with the present epoch
论文作者
论文摘要
我们报告了从恒星簇形成的三个辐射流体动力学模拟获得的恒星和棕色矮人的统计特性，其金属度为1、1/10和1/100太阳值。恒星形成云受到宇宙微波背景辐射，适用于红移Z = 5的恒星形成。将三个计算的结果彼此进行比较，并与先前发布的计算相似，该计算的背景辐射水平适合于当今（Z = 0）恒星形成。每个计算分别处理灰尘和气体温度，并包括弥漫性星际介质的热化学模型。我们发现，尽管恒星质量分布对当今恒星形成的金属性不敏感，但在Z = 5时，与银河系最初的质量功能相比，特征恒星质量随着金属性的增加而增加，质量分布的质量不足，在太阳金属性上的棕色矮星和低质量恒星的不足。我们还发现，M-dwarfs的多样性随着z = 5时的金属性增加而降低。这些作用是由于金属富含气体无法冷却至z = 5的低温，而在z = 0处的低温是由于较热的宇宙微波背景辐射，这会抑制高密度下的碎裂。
We report the statistical properties of stars and brown dwarfs obtained from three radiation hydrodynamical simulations of star cluster formation with metallicities of 1, 1/10 and 1/100 of the solar value. The star-forming clouds are subjected to cosmic microwave background radiation that is appropriate for star formation at a redshift z=5. The results from the three calculations are compared to each other, and to similar previously published calculations that had levels of background radiation appropriate for present-day (z=0) star formation. Each of the calculations treat dust and gas temperatures separately and include a thermochemical model of the diffuse interstellar medium. We find that whereas the stellar mass distribution is insensitive to the metallicity for present-day star formation, at z=5 the characteristic stellar mass increases with increasing metallicity and the mass distribution has a deficit of brown dwarfs and low-mass stars at solar metallicity compared to the Galactic initial mass function. We also find that the multiplicity of M-dwarfs decreases with increasing metallicity at z=5. These effects are a result of metal-rich gas being unable to cool to as low temperatures at z=5 compared to at z=0 due to the hotter cosmic microwave background radiation, which inhibits fragmentation at high densities.
