标题： 星系际介质中粒度分布的演化 显示英文标题

标题： Evolution of grain size distribution in the circum-galactic medium

摘要： 为了从理论上理解星系际介质（CGM）中的尘埃属性，我们构建了一个包含颗粒尺寸分布演化的尘埃演化模型。 我们将每个星系和CGM都视为一个单区对象，并考虑它们之间的质量交换。 我们基于之前的模型，考虑了星系中的尘埃产生和星际尘埃加工过程，同时首次将CGM中的高温相溅射和低温相破碎纳入模型。 我们发现，在CGM中破碎会增加尘埃破坏（溅射）的效率。 CGM中颗粒尺寸分布的功能形状随星系中的演化而变化，但其对CGM中溅射和破碎之间的平衡非常敏感。 为了进行观测测试，我们讨论了由背景类星体颜色追踪的CGM中消光的波长依赖性，认为为了解释观测到的消光水平，由于快速的尘埃/金属富集，CGM向星系的快速吸积更为有利。 CGM中通过破碎产生的小颗粒也有助于解释短波长方向上尘埃消光的上升趋势。 显示英文摘要

摘要： In order to theoretically understand dust properties in the circum-galactic medium (CGM), we construct a dust evolution model that incorporates the evolution of grain size distribution. We treat each of the galaxy and the CGM as a one-zone object, and consider the mass exchange between them. We take into account dust production and interstellar dust processing for the galaxy based on our previous models, and newly incorporate sputtering in the hot phase and shattering in the cool phase for the CGM. We find that shattering increases the dust destruction (sputtering) efficiency in the CGM. The functional shape of the grain size distribution in the CGM evolves following that in the galaxy, but it is sensitive to the balance between sputtering and shattering in the CGM. For an observational test, we discuss the wavelength dependence of the reddening in the CGM traced by background quasar colors, arguing that, in order to explain the observed reddening level, a rapid inflow from the CGM to the galaxy is favored because of quick dust/metal enrichment. Small grain production by shattering in the CGM also helps to explain the rise of dust extinction toward short wavelengths.