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和观测


银河风塑造了星系的恒星、气体和金属含量。为了量化它们的影响，我们必须了解它们的物理特性。我们回顾了潜在的风驱动机制和观察到的风特性，重点是温暖的电离和热 X 射线发射气体。根据观测结果，考虑了超新星 （SNe）、宇宙射线、辐射压力和磁场的能量和动量注入：▪冷/暖气体的发射和吸收线测量为我们对银河系流出提供了最好的物理诊断。 ▪尽管不存在单一机制的决定性证据，但观察到的动量、能量和质量负载预算与理论相当。 ▪风能是 SNe 提供的风能的 ∼0.1.▪非常热的 X 射线发射相位可能是（或）原动机。热相和冷相之间的动量和能量交换对气体动力学至关重要。▪我们观测知识的差距包括热气运动学以及用紫外线吸收线探测的流出的大小和结构。需要模拟来更全面地了解混合、云-辐射、云-宇宙射线和云-热风相互作用、星团的集体效应以及分布式和集群 SNe。观测工作应在风数据中寻找为特定机制提供证据的二级相关性，并将光谱学与理论中的柱密度-速度结果进行比较。