Photon Escape from the Interstellar Medium

从小尺度行星的形成到大尺度星际介质的演化，星际介质的物理在天文学和天体物理学的许多领域都起着至关重要的作用。后者又通过不同的反馈效应，如金属的富集化和再电离，与星系的形成和演化过程有非常紧密的相互作用，这可以改变IGM的热状态，减少气体的积累，甚至在小质量星系中蒸发气体。因此，对ISM物理学的理解对于更广泛地理解我们今天观察到的宇宙是如何形成的至关重要。这是因为星系向IGM发射的辐射量除其他外取决于星系内恒星的丰度、它们的分布以及ISM内中性气体和尘埃的分布。尽管它具有相关性，而且最近在ISM调查的理论和观测方面取得了进展，但许多重要的问题仍然悬而未决。其中，与光子从ISM逃逸到IGM有关的问题。最近对局部宇宙和高红移的逃逸分数的经验测量通常产生了几个百分比范围内的适中数值。相比之下，理论研究在很大程度上是不确定的。在这里，我们建议使用最先进的3D流体动力学和辐射传输模拟来研究这一重要的开放问题。

The physics of the interstellar medium (ISM) plays a crucial role in many areas of astronomy and astrophysics, from the formation of planets on small scales, to the evolution of the intergalactic medium (IGM) on large scales. The latter in turn has a very tight interplay with the galaxy formation and evolution process via different feedback effects, such as metal enrichment and reionization, which can alter the IGM thermal state, reduce gas accretion or even evaporate gas in small mass galaxies. The understanding of the physics of the ISM is thus of paramount importance for the broader understanding of how the universe we observe today has taken shape. This because the amount of radiation emitted by galaxies into the IGM depends, among others, on the abundance of stars within a galaxy, their distribution, as well as the distribution of neutral gas and dust within the ISM. Despite its relevance, and much recent theoretical and observational progress in the investigation of the ISM, many important questions still remain open. Among which, those related to the escape of photons from the ISM into the IGM. Recent empirical measurements of the escape fraction in the local universe and at high redshift have generally produced modest values in the range of a few percent. In contrast, theoretical studies have largely been inconclusive. Here we propose to investigate this important open problem using state of the art 3D hydro-dynamical and radiative transfer simulations.