Galactic winds shape the stellar, gas, and metal content of galaxies. To quantify their impact, we must understand their physics. We review potential wind-driving mechanisms and observed wind properties, with a focus on the warm ionized and hot X-ray-emitting gas. Energy and momentum injection by supernovae (SNe), cosmic rays, radiation pressure, and magnetic fields are considered in the light of observations:▪Emission and absorption line measurements of cool/warm gas provide our best physical diagnostics of galactic outflows.▪The critical unsolved problem is how to accelerate cool gas to the high velocities observed. Although conclusive evidence for no one mechanism exists, the momentum, energy, and mass-loading budgets observed compare well with theory.▪A model in which star formation provides a force ∼L/c, where L is the bolometric luminosity, and cool gas is pushed out of the galaxy's gravitational potential, compares well with available data. The wind power is ∼0.1 of that provided by SNe.▪The very hot X-ray-emitting phase may be a (or the) prime mover. Momentum and energy exchange between the hot and cooler phases is critical to the gas dynamics.▪Gaps in our observational knowledge include the hot gas kinematics and the size and structure of the outflows probed with UV absorption lines.Simulations are needed to more fully understand mixing, cloud–radiation, cloud–cosmic ray, andcloud–hot wind interactions, the collective effects of star clusters, and both distributed andclustered SNe. Observational works should seek secondary correlations in the wind data thatprovide evidence for specific mechanisms and compare spectroscopy with the column density–velocity results from theory.

中文翻译：

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恒星形成星系风的理论与观测


银河风塑造了星系中的恒星、气体和金属成分。为了量化它们的影响，我们必须了解它们的物理原理。我们回顾了潜在的风驱动机制并观察了风的特性，重点关注温暖的电离和热 X 射线发射气体。根据观测考虑超新星 (SNe)、宇宙射线、辐射压和磁场注入的能量和动量：▪冷/暖气体的发射和吸收线测量为我们提供了银河流出的最佳物理诊断。▪关键未解决的问题是如何将冷气体加速到观察到的高速。虽然不存在任何一种机制确实的证据，但观察到的动量、能量和质量负载预算与理论相比较。▪一个模型，其中恒星形成提供力~L/c，其中L是测辐射热光度，冷气体被推出银河系的引力势，与现有数据相比较。风能是超新星提供的～0.1。▪非常热的X射线发射相可能是原动机。热相和冷相之间的动量和能量交换对于气体动力学至关重要。▪我们观测知识中的差距包括热气体运动学以及用紫外线吸收线探测的流出物的尺寸和结构。需要进行模拟以更全面地了解混合、云-辐射、云-宇宙线、云-热风相互作用、星团的集体效应以及分布式和簇状超新星。观测工作应寻找风数据中的二次相关性，为特定机制提供证据，并将光谱学与理论的柱密度-速度结果进行比较。