A model of supernova feedback in galaxy formation
A model of supernova feedback in galaxy formation
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DOI：
10.1046/j.1365-8711.2000.03665.x
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发表时间：
2000-02
影响因子：
4.8
通讯作者：
G. Efstathiou
中科院分区：
文献类型：
--
作者：
G. Efstathiou
摘要建立了盘状星系形成过程中的超新星反馈模型。该模型包含了来自晕的冷却气体的流入和来自多相星际介质（ISM）的热气体的流出。恒星的形成速率是通过平衡冷气体云之间碰撞所耗散的能量与在不稳定到轴对称不稳定的圆盘上的超新星所提供的能量来确定的。热气体是由超新星残骸中的冷气体云的热蒸发产生的，并推导出标准来估计热成分的特征温度和密度，从而估计净质量流出率。对该模型进行了许多改进，包括一个简单的星系喷泉模型、冷成分对热气体压力的响应、压力诱导的恒星形成和化学演化。这篇论文的主要结论是，低恒星形成率可以从矮星系中排出大部分气体。例如，一个以50 km / s / 21的圆周速度运行的星系可以在1 Gyr的时间尺度上排出60% - 80%的气体，而恒星形成速度永远不会超过0.1 M / s / 21。因此，有效反馈可以在静止模式下发生，而不需要强烈的恒星形成爆发。即使是像银河系这样的大型星系，也可能在超新星驱动的风中损失了多达20%的质量。这里开发的模型表明，高红移的矮星系平均恒星形成率较低，可能包含大量未加工气体的延伸气体盘。这种扩展的气体盘可以解释阻尼莱曼a系统的数量、金属丰度和金属丰度色散。
ABSTRA C T A model of supernova feedback during disc galaxy formation is developed. The model incorporates infall of cooling gas from a halo, and outflow of hot gas from a multiphase interstellar medium (ISM). The star formation rate is determined by balancing the energy dissipated in collisions between cold gas clouds with that supplied by supernovae in a disc marginally unstable to axisymmetric instabilities. Hot gas is created by thermal evaporation of cold gas clouds in supernova remnants, and criteria are derived to estimate the characteristic temperature and density of the hot component and hence the net mass outflow rate. A number of refinements of the model are investigated, including a simple model of a galactic fountain, the response of the cold component to the pressure of the hot gas, pressure-induced star formation and chemical evolution. The main conclusion of this paper is that low rates of star formation can expel a large fraction of the gas from a dwarf galaxy. For example, a galaxy with circular speed ,50 km s 21 can expel ,60‐80 per cent of its gas over a time-scale of ,1 Gyr, with a star formation rate that never exceeds ,0.1 M( yr 21 . Effective feedback can therefore take place in a quiescent mode and does not require strong bursts of star formation. Even a large galaxy, such as the Milky Way, might have lost as much as 20 per cent of its mass in a supernova-driven wind. The models developed here suggest that dwarf galaxies at high redshifts will have low average star formation rates and may contain extended gaseous discs of largely unprocessed gas. Such extended gaseous discs might explain the numbers, metallicities and metallicity dispersions of damped Lyman a systems.