Squaring the circle: making sense of the dusty, magnetized interstellar medium beyond two dimensions

星际介质（ISM），即银河系中恒星之间的气体和尘埃，是新恒星和行星诞生的巨大储存库，因此是理解星系演化的核心。气相范围从冷到热，从分子到原子，从中性到电离，具有重要的动态磁场和湍流运动，ISM处于混乱状态。物理过程和天文现象的复杂性扩展了我们的理解能力，为我的团队中的年轻研究人员提供了一个刺激的培训环境，他们利用计算天体物理学、统计学和数据密集型分析，在非常极端的条件下应用广泛的现代物理学。利用普朗克卫星，我们在偏振热发射分析方面取得了很大进展。尘埃和相关的磁场在天空中的投影，缺乏距离和三维视角，需要深入了解。然而，这一切即将改变，一场由盖亚卫星提供的数十亿恒星距离引发的革命。通过量化恒星的尘埃消光（散射加吸收）来定位距离上的尘埃。为了确保深入探索致密分子恒星形成云中的尘埃，我的团队将对恒星进行光谱分类，这是一种新型多路红外光谱仪WIFIS的新应用。为了获得最佳的角度分辨率和3D分布，我们将利用赫歇尔热发射技术制作新的尘埃光学深度图。尘埃如何随3D环境演变需要新的见解。我们将专注于一组独特的观测，明确地在多个频率测量相同的尘埃，旨在建立自一致的尘埃模型。亚毫米光学深度与光学消光的比值将被校准，量化三维不透明度的演变。测量散射光的数量，利用蜻蜓远摄阵列的超宽视场灵敏度，与热辐射相比，将通过反照率和相位函数提供补充证据。与星际极化相比，BLAST-TNG观测的热尘埃发射分数极化的频率依赖性将严格限制尘埃成分的混合。我们正在开发更复杂的三维模型和磁化ISM的模拟，包括静态和动态，结合结构如何随着磁场的变化而演变。我们已经证明，在投影中，ISM结构和磁场的相对取向在漫射介质中是平行的，但在高柱密度时是垂直的。我们将在更高的角分辨率下使用BLAST-TNG进一步探索尘埃极化。我们的模型雄心勃勃的解决了银河尘埃前景b模极化如何污染原始宇宙b模信号，密集区域的颗粒排列，以及磁场在云聚集和支持中的作用。

The interstellar medium (ISM), gas and dust between the stars in the Milky Way, is a vast reservoir from which new stars and planets are being born, and so at the heart of understanding galaxy evolution. With gas phases ranging from cold to hot, molecular to atomic, and neutral to ionized, a dynamically important magnetic field, and turbulent motions, the ISM is in turmoil. The complexity of physical processes and astronomical phenomena stretch our ability to comprehend a stimulating training environment for young researchers on my team, who draw on computational astrophysics, statistics, and data-intensive analysis to apply a broad range of modern physics in very extreme conditions.Using the Planck satellite, we made great progress analysing polarized thermal emission. Dust and associated magnetic fields are seen in projection on the sky, lacking distances and the 3D perspective needed for deep understanding. However, this is about to change, a revolution launched by billions of stellar distances provided by the Gaia satellite. Quantifying dust extinction (scattering plus absorption) of stars locates the dust in distance. To ensure that dust in dense molecular star-forming clouds is probed deeply, my team will make spectral classifications of stars, a novel application of a new multiplexing infrared spectrograph WIFIS. For the best angular resolution, and so 3D distribution, we will produce new maps of dust optical depth based on thermal emission using Herschel.How dust evolves with 3D environment requires new insights. We will focus on a unique set of observations that explicitly measure the same dust at multiple frequencies, aiming for self-consistent dust models. The ratio of optical depth in the submillimetre to extinction in the optical will be calibrated, quantifying the evolution of opacity in 3D. Measuring the amount of scattered light, exploiting the superb wide field sensitivity of the Dragonfly Telephoto Array, compared to thermal emission will provide complementary evidence via albedo and phase function. BLAST-TNG observations of the frequency dependence of the fractional polarization of thermal dust emission compared to interstellar polarization will tightly constrain mixtures of dust components.We are developing more sophisticated 3D models and simulations of the magnetized ISM, both static and dynamic, incorporating how structures evolve in relation to the magnetic field. We have shown that in projection the relative orientation of ISM structures and the magnetic field is parallel in the diffuse medium, but perpendicular at high column density. We will explore dust polarization further with BLAST-TNG at higher angular resolution. Our models ambitiously tackle how the Galactic dust foreground B-mode polarization contaminates the primordial cosmological B-mode signal, grain alignment in dense regions, and the role of the magnetic field in cloud assembly and support.