The lifecycle of grains in the evolving, multiphase ISM

尘埃颗粒是存在于任何星系星际空间的微小固体颗粒。这些颗粒吸收了恒星的辐射，完全改变了星系的外观。为了从星系中去除尘埃面纱，并从观测中正确地推断出它们的参数，人们需要了解不同环境下的尘埃特性，而这些特性目前还没有得到很好的理解。我的研究旨在建立一幅星际颗粒生命周期的一致图景：它们是如何在星际气体中形成、加工和破坏的。颗粒诞生于老恒星和超新星周围的冷却气体中。由于理论模型的最新进展，恒星在尘埃颗粒产生中的作用现在得到了更好的理解。颗粒在星际空间的后续旅程更为复杂，理论上的研究较少。这类研究面临的主要挑战是星际尘埃和气体的演化是相互关联的。我的项目旨在通过同时模拟星系气体和尘埃的演化来克服这一挑战。我们将按照尘埃生命周期的所有阶段进行星系演化的三维流体动力学模拟。这些模拟将告诉我们，在整个星系中，颗粒特性是如何变化的。虽然尘埃颗粒只占银河系气体质量的1%，但它们对气体的加热和冷却以及氢分子的形成非常重要，氢分子是形成恒星和行星最重要的分子。大多数星系流体动力学模拟都假定颗粒保持不变。了解颗粒的实际特性将使星系演化、恒星形成的建模更加真实，并有助于更准确地解释星系的观测结果。

Dust grains are tiny solid particles that are present in the interstellar space of any galaxy. These grains absorb the radiation from stars and completely change the appearance of galaxies. In order to remove the dust veil from galaxies and correctly infer their parameters from observations, one needs to know dust properties in different environments, which are not well understood. My research aims to build a consistent picture of the lifecycle of interstellar grains: how they are formed, processed and destroyed in the interstellar gas.Grains are born in cooling gas around old stars and supernovae. The role of stars in the production of dust grains is much better understood now due to recent advances in theoretical models. The following journey of grains in the interstellar space is more complex and less studied theoretically. The major challenge for such studies is that the evolution of interstellar dust and gas are interrelated. My project aims to overcome this challenge by modelling galactic gas and dust evolution simultaneously. We will perform three-dimensional hydrodynamic simulations of galactic evolution that follow all stages of the lifecycle of dust. These simulations will tell us how grain properties vary across the galaxy.Although dust grains constitute only 1% of the gas mass in our galaxy, they are very important for heating and cooling of the gas and for the formation of hydrogen molecules, the most important molecule for formation of stars and planets. Most hydrodynamic simulations of galaxies assume that grains remain the same. Knowing actual properties of grains will enable more realistic modeling of galactic evolution, star formation and help to more accurately interpret the observations of galaxies.