Development of Sub-Millimetre Heterodyne Array & Probing the Interstellar Medium of Nearby Galaxies with JWST and ALMA

这个D. Phil该方案包括两个互补的科学主题：重点发展亚毫米量子探测器，以及利用JWST和阿尔马的中红外数据进行观测项目。通过在毫米和亚毫米波段进行观测，可以确定恒星形成区域的物理和化学条件，在这些波段可以发现大量的原子、离子和分子谱线。近年来，对这些谱线的分光和干涉观测，使我们对附近和遥远星系的气体动力学和运动学的知识更加完善，并使我们能够首次直接探测到黑洞图像。这些观测之所以成为可能，是因为近量子噪声限制的超导体-绝缘体-超导体（SIS）外差接收器具有非凡的特性。SIS混合器通常用于诸如北方扩展毫米阵列（NOEMA）、阿塔卡马大型毫米/亚毫米阵列（阿尔马）和赫歇尔空间天文台等天文台，从而能够以高光谱和空间分辨率对微弱天体进行大量观测。然而，有一个主要的限制，利用SIS接收器在不久的将来的天文观测，无论是地面或空间-传统的高光谱分辨率观测需要过多的望远镜时间。这阻碍了重要的科学计划，特别是在补充大面积连续体测绘数据时，例如，赫歇尔上缺乏动力学和运动学信息的测辐射热阵列，或需要大面积高空间和光谱分辨率的科学。提高绘图速度需要增加检测器的数量和/或提高灵敏度。然而，大多数现有的亚毫米仪器都没有达到最终的量子极限，这对于成像高z星系和黑洞至关重要。此外，这些仪器通常拥有有限数量的空间像素，这使得绘制银河平面和附近星系内的大型结构成为一项艰巨的挑战。现在需要新一代超灵敏的宽视场基础设施，例如，计划的地基（例如，AtLAST，LST）和天基（例如，NASA探测器）望远镜，预计将配备大像素数外差阵列（~103像素），必须在保持非凡水平的单个像素灵敏度的同时建造。只有在所需技术发展到高TRL，包括在现有望远镜上进行小规模演示之后，才有可能有信心地计划建造大型仪器。这个D. Phil因此，该项目旨在通过开发小像素数亚毫米外差阵列来应对这些挑战，在每个阶段都涉及先进技术，使其模块化和可阵列化，着眼于未来能够部署千像素接收器。该项目的目标是通过开发一个双偏振亚毫米外差演示器来演示这些技术，该演示器将保留完整的天文信号强度并保留偏振信息。对于科学观测部分，学生将侧重于使用詹姆斯韦伯太空望远镜（JWST）中红外光谱仪（MIRI）和阿塔卡马大型毫米阵列（阿尔马）的数据对附近星系样本的星际介质进行调查。JWST的出现为我们提供了前所未有的灵敏度和空间分辨率，使ISM的属性在空间分辨的方式在星系附近和远处的研究。该项目将侧重于附近星系的样本，并将首次根据不受温度依赖性影响的中红外离子线检查元素丰度，因此将提供对金属丰度梯度的可靠估计。此外，学生还将比较分子气体的分布（通常用于跟踪原始物质

This D.Phil. programme is comprising two complementary science topics: A focus on the development of the sub-millimetre quantum detector, and an observation project utilising mid-infrared (MIR) data from JWST and ALMA.The physical and chemical conditions in star-forming regions can be determined by observing at millimetre and sub-millimetre wavelengths, where a host of atomic, ionic and molecular lines can be found. In recent years, spectroscopic and interferometric observations of these lines have refined our knowledge of the gas dynamics and kinematics of nearby and distant galaxies, as well as enabling the first direct detection of black hole images. These observations have only been possible because of the extraordinary characteristics of near quantum-noise-limited Superconductor-Insulator-Superconductor (SIS) heterodyne receivers. SIS mixers are used routinely on observatories such as the Northern Extended Millimetre Array (NOEMA), the Atacama Large Millimetre/sub-millimetre Array (ALMA), and the Herschel space observatory, to name a few, enabling numerous observations of faint objects with high spectral and spatial resolution. However, there is a major limitation in utilising SIS receivers for near future astronomical observation, either ground-based or space-borne.Traditional high spectral resolution observations demand excessive telescope time. This hampers important scientific programs, especially when complementing large-area continuum mapping data done by e.g., bolometric arrays on Herschel which lack of dynamic and kinematic information, or science that require large area high spatial and spectral resolution. Improving mapping speed entails increasing the number of detectors and/or enhancing sensitivity. However, most existing sub-mm instruments fall short of reaching the ultimate quantum limit, crucial for imaging high-z galaxies and black holes. Additionally, these instruments often possess a limited number of spatial pixels, making mapping large structure within the Galactic plane and nearby galaxies a formidable challenge.A new generation of ultra-sensitive wide-field infrastructure is now required e.g., the planned ground-based (e.g., AtLAST, LST) and space-based (e.g., NASA Probe) telescopes, that are expected to be equipped with large pixel count heterodyne arrays (~103 pixels) and must be built whilst retaining extraordinary levels of individual-pixel sensitivity. It is only possible to plan the construction of large instruments with confidence, once the needed technology has been developed to high TRL, including smaller-scale demonstration on existing telescopes. This D.Phil. project therefore aim to address these challenges by developing a small-pixel count sub-millimetre heterodyne array, involving advancing techniques at every stage, making them modular and array-able, with an eye towards enabling the future deployment of kilo-pixel receivers. The project targets to demonstrate the technologies by developing a dual-polarisation sub-millimetre heterodyne demonstrator, which would retain the full astronomical signal strength and preserve the polarisation information. For the scientific observation part, the student will focus on an investigation of the Interstellar Medium of a sample of nearby galaxies using data from the James Webb Space Telescope (JWST) Mid-Infrared Spectrometer (MIRI) and the Atacama Large Millimetre Array (ALMA). The advent of JWST has provided us with unprecedented sensitivity and spatial resolution to enable studies of the properties of the ISM in a spatially resolved manner in galaxies near and far. The project will focus on a sample of nearby galaxies and will examine, for the first time, element abundances based on mid-infrared (MIR) ionic lines which are unaffected by temperature dependencies and therefore will deliver robust estimates of metallicity gradients. Furthermore, the student will compare the distribution of molecular gas (often used to trace the raw ma