The lifecycle of grains in the evolving, multiphase ISM

尘埃颗粒是存在于任何星系的星际空间中的微小固体颗粒。这些颗粒吸收恒星的辐射，完全改变了星系的面貌。为了揭开星系的尘埃面纱并从观测中正确地推断出它们的参数，人们需要知道不同环境中的尘埃属性，而这些属性还没有被很好地理解。我的研究旨在建立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、加工和销毁的。颗粒诞生于旧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，现在人们对恒星在尘埃颗粒产生中的作用有了更好的理解。颗粒在星际空间的后续旅程更加复杂，理论上的研究也较少。这类研究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。我们将对尘埃生命周期的所有阶段进行星系演化的三维流体力学模拟。这些模拟将告诉我们整个星系的颗粒特性是如何变化的。虽然尘埃颗粒只占我们银河系气体质量的1%，但它们对于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的最重要的分子。大多数星系的流体动力学模拟都假设颗粒保持不变。了解颗粒的实际性质将使星系演化、恒星形成的模型更加逼真，并有助于更准确地解释星系的观测。

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.