This paper presents a new framework for understanding the relationship between a galaxy and its circumgalactic medium (CGM). It focuses on how imbalances between heating and cooling cause either expansion or contraction of the CGM. It does this by tracking all of the mass and energy associated with a halo’s baryons, including their gravitational potential energy, even if feedback has pushed some of those baryons beyond the halo’s virial radius. We show how a star-forming galaxy’s equilibrium state can be algebraically derived within the context of this framework, and we analyze how the equilibrium star formation rate depends on supernova feedback. We consider the consequences of varying the mass loading parameter ηM≡Ṁwind/Ṁ* relating a galaxy’s gas mass outflow rate ( Ṁwind ) to its star formation rate ( Ṁ* ) and obtain results that challenge common assumptions. In particular, we find that equilibrium star formation rates in low-mass galaxies are generally insensitive to mass loading, and when mass loading does matter, increasing it actually results in more star formation because more supernova energy is needed to resist atmospheric contraction.

中文翻译：

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银河系大气的平衡状态。I. 质量加载的另一面


本文为理解星系与其银河系周围介质 （CGM） 之间的关系提出了一个新的框架。它侧重于加热和冷却之间的不平衡如何导致 CGM 的膨胀或收缩。它通过跟踪与光晕重子相关的所有质量和能量（包括它们的引力势能）来实现这一点，即使反馈已将其中一些重子推到了光晕的维里半径之外。我们展示了如何在该框架的背景下以代数方式推导出恒星形成星系的平衡状态，并分析平衡恒星形成速率如何取决于超新星反馈。我们考虑了改变质量载荷参数 ηM≡Ṁwind/Ṁ* 的后果，将星系的气体质量流出率 （Ṁwind） 与其恒星形成速率 （Ṁ* ） 相关联，并获得了挑战常见假设的结果。特别是，我们发现低质量星系中的平衡恒星形成速率通常对质量载荷不敏感，当质量载荷确实很重要时，增加它实际上会导致更多的恒星形成，因为需要更多的超新星能量来抵抗大气收缩。