The Initial Mass Function of the First Stars Inferred from Extremely Metal-poor Stars
The Initial Mass Function of the First Stars Inferred from Extremely Metal-poor Stars
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DOI：
10.3847/1538-4357/aab3de
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发表时间：
2018-04-10
影响因子：
4.9
通讯作者：
Nomoto, Ken'ichi
中科院分区：
文献类型：
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作者：
Ishigaki, Miho N.;Tominaga, Nozomu;Nomoto, Ken'ichi
我们比较了类似200颗极贫金属（EMP; [Fe/H] < -3）恒星的元素丰度模式与无金属恒星的超新星产量，以便深入了解宇宙中第一批（星族III或Pop III）恒星的特征质量。超新星产量是通过核合成计算得到的，这些无金属恒星具有不同的初始质量（M = 13、15、25、40和100M（圆点））和爆炸能量（E-51 = E/10(51)[erg] = 0.5-60），包括低能、正常能和高能爆炸。我们采用混合回退模型，以考虑超新星爆炸中可能存在的不对称性，并通过改变模型参数来寻找最适合观测到的EMP恒星丰度模式的产率。我们发现，EMP恒星的丰度模式主要与初始质量M < 40M（圆点）的超新星产量最吻合，并且超过一半的恒星最适合M = 25M（圆点）超新星（E-51 = 10）模型。结果还表明，大多数原始超新星都喷射出了10(-2)-10(-1)M（圆点）的Ni-56，留下了致密的遗迹（中子星或黑洞），质量在1.5-5M（圆点）之间。这些结果表明，负责第一次金属富集的第一批恒星的质量主要小于40M（圆点）。这意味着高质量第一恒星要么数量较少，直接坍缩成黑洞而没有喷射出重元素，要么高质量第一恒星的超新星爆炸抑制了下一代低质量恒星的形成，[Fe/H] < -3。
We compare the elemental abundance patterns of similar to 200 extremely metal-poor (EMP; [Fe/H] < -3) stars to the supernova yields of metal-free stars, in order to obtain insights into the characteristic masses of the first (Population III or Pop III) stars in the universe. The supernova yields are prepared with nucleosynthesis calculations of metal-free stars with various initial masses (M = 13, 15, 25, 40 and 100M(circle dot)) and explosion energies (E-51 = E/10(51)[erg] = 0.5-60), to include low-energy, normal-energy, and high-energy explosions. We adopt the mixing-fallback model, to take into account possible asymmetry in the supernova explosions, and the yields that best fit the observed abundance patterns of the EMP stars are searched by varying the model parameters. We find that the abundance patterns of the EMP stars are predominantly best-fitted by the supernova yields with initial masses M < 40M(circle dot), and that more than than half of the stars are best-fitted by the M = 25M(circle dot) hypernova (E-51 = 10) models. The results also indicate that the majority of the primordial supernovae have ejected 10(-2)-10(-1)M(circle dot) of Ni-56, leaving behind a compact remnant (either a neutron star or a black hole), with a mass in the range of similar to 1.5-5M(circle dot). These results suggest that the masses of the first stars responsible for the first metal enrichment are predominantly < 40M(circle dot). This implies that the higher-mass first stars were either less abundant, directly collapsed into a black hole without ejecting heavy elements, or a supernova explosion of a higher-mass first star inhibits the formation of the next generation of low-mass stars at [Fe/H] < -3.