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arXiv 0808.2645astro-ph
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星暴星系的DLA运动学和外流

DLA kinematics and outflows from starburst galaxies

Alexei O. Razoumov

摘要:

我们提出的结果,从数值研究的多相星际介质亚莱曼break星系原星系团。这样的团块在z=3处是丰富的,并且被认为是阻尼Ly-alpha吸收的主要贡献者。我们模拟了这些团块形成风的过程,并表明在恒星形成过程中,它们具有中性气体速度宽度高达数百公里/秒的外流。这样的外流是一致的,所观察到的高速分散在DLAs。在我们的模型中,只有当冷云(~ 300 K)、稠密云(> 100 msun/pc ^3)的网格分辨率为12 pc时,风和超新星的热能反馈才能导致有效的外流。在较低的24 pc分辨率下,多相介质的第一个迹象被发现;然而,在这个低分辨率下,反馈能量的热注入还不能在恒星形成区域周围产生热膨胀气泡-相反,反馈往往会消除高密度峰值并抑制恒星形成。在12 pc分辨率下,反馈压缩冷云,通常不会破坏正在进行的恒星形成;同时,更大部分的反馈能量被引导到低密度的气泡和风中。这些风经常夹带紧凑的中性团块,产生多组分金属吸收线。

英文摘要:

We present results from a numerical study of the multiphase interstellar medium in sub-Lyman-break galaxy protogalactic clumps. Such clumps are abundant at z=3 and are thought to be a major contributor to damped Ly-alpha absorption. We model the formation of winds from these clumps and show that during star formation episodes they feature outflows with neutral gas velocity widths up to several hundred km/s. Such outflows are consistent with the observed high-velocity dispersion in DLAs. In our models thermal energy feedback from winds and supernovae results in efficient outflows only when cold (~ 300 K), dense (> 100 msun/pc^3) clouds are resolved at grid resolution of 12 pc. At lower 24 pc resolution the first signs of the multiphase medium are spotted; however, at this low resolution thermal injection of feedback energy cannot yet create hot expanding bubbles around star-forming regions -- instead feedback tends to erase high-density peaks and suppress star formation. At 12 pc resolution feedback compresses cold clouds, often without disrupting the ongoing star formation; at the same time a larger fraction of feedback energy is channeled into low-density bubbles and winds. These winds often entrain compact neutral clumps which produce multi-component metal absorption lines.

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