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arXiv 1807.04288astro-ph.GA
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矮星的宇宙学模拟:对ISM物理学的需要超出了SN单独反馈

Cosmological simulations of dwarfs: the need for ISM physics beyond SN feedback alone

Matthew C. Smith, Debora Sijacki, Sijing Shen

摘要:

在低质量晕中占主导地位的反馈机制通常被认为是大质量恒星爆炸为超新星(SNe)的形式。我们进行了非常高分辨率的宇宙学放大模拟的五个矮星系z = 4与我们的机械SN反馈模型。这提供了正确的动量,对应于SN残余演化阶段的解决,并已被证明在孤立的模拟中导致现实的矮属性。我们发现,在我们模拟的5个宇宙学矮星中,有4个SN反馈的影响不足,导致恒星质量过大,非常紧凑的尺寸和中央超太阳恒星金属丰度。在我们的模型中,我们的矮星中SN反馈的失败是物理性质的,并且是由于在第一个SN发生之前合并和宇宙流入而在早期宇宙中形成非常致密的气体的结果。我们证明,我们的结果是不敏感的分辨率(只要它是足够高的),(空间均匀)的紫外背景的细节和合理的变化,在我们的恒星形成处方。因此,我们得出结论,SNe调节矮星系性质的能力取决于其他物理过程,如湍流压力支持,聚集和失控的SN祖先和其他来源的恒星反馈。

英文摘要:

The dominant feedback mechanism in low mass haloes is usually assumed to take the form of massive stars exploding as supernovae (SNe). We perform very high resolution cosmological zoom-in simulations of five dwarf galaxies to z = 4 with our mechanical SN feedback model. This delivers the correct amount of momentum corresponding to the stage of the SN remnant evolution resolved, and has been shown to lead to realistic dwarf properties in isolated simulations. We find that in 4 out of our 5 simulated cosmological dwarfs, SN feedback has insufficient impact resulting in excessive stellar masses, extremely compact sizes and central super-solar stellar metallicities. The failure of the SN feedback in our dwarfs is physical in nature within our model and is the result of the build up of very dense gas in the early universe due to mergers and cosmic inflows prior to the first SN occurring. We demonstrate that our results are insensitive to resolution (provided that it is high enough), details of the (spatially uniform) UV background and reasonable alterations within our star formation prescription. We therefore conclude that the ability of SNe to regulate dwarf galaxy properties is dependent on other physical processes, such as turbulent pressure support, clustering and runaway of SN progenitors and other sources of stellar feedback.

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