arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1003.0676astro-ph.CO
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伴随着暗物质湮灭的第一个恒星形成

First star formation with dark matter annihilation

E. Ripamonti, F. Iocco, A. Ferrara, R. Schneider, A. Bressan, P. Marigo

摘要:

我们包括一个能量项的基础上暗物质(DM)在冷却和随后的崩溃的无金属气体,在晕托管形成的第一颗恒星在宇宙中的自我湮灭。我们已经发现,在整个坍缩过程中,云的化学性质引起的反馈确实改变了气体的性质。然而,修改是不显着的,和典型的金斯质量内的光环是保守的整个崩溃,为所有的DM参数,我们已经考虑。这一结果意味着,相对于不考虑这种额外能量项的标准情况,暗物质湮灭的存在并没有实质性地改变第一恒星的初始质量函数。我们还发现,当DM湮灭所产生的能量和气体所吸收的能量的比率等于化学冷却时(在离原恒星核的实际形成还很远的密度下),该结构并没有停止坍缩,尽管坍缩进行得更慢,比总坍缩时间的百分之几小。

英文摘要:

We include an energy term based on Dark Matter (DM) self-annihilation during the cooling and subsequent collapse of the metal-free gas, in halos hosting the formation of the first stars in the Universe. We have found that the feedback induced on the chemistry of the cloud does modify the properties of the gas throughout the collapse. However, the modifications are not dramatic, and the typical Jeans mass within the halo is conserved throughout the collapse, for all the DM parameters we have considered. This result implies that the presence of Dark Matter annihilations does not substantially modify the Initial Mass Function of the First Stars, with respect to the standard case in which such additional energy term is not taken into account. We have also found that when the rate of energy produced by the DM annihilations and absorbed by the gas equals the chemical cooling (at densities yet far from the actual formation of a proto-stellar core) the structure does not halt its collapse, although that proceeds more slowly by a factor smaller than few per cent of the total collapse time.

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