The evolution of the dynamics and chemistry of star forming galaxies across cosmic time

哈勃星系形态序列仍然是星系的定义特征之一，并提供了星系形成模型努力重现的关键约束之一。局部星系的动力学研究表明，哈勃星系形态序列遵循固定质量下角动量增加的序列。在冷暗物质范式中，星系形成于暗物质晕的中心。当气体在暗晕内坍缩时，重子既可以失去角动量，也可以获得角动量。如果重子的角动量在坍缩过程中（弱）守恒，它们将形成一个具有指数光轮廓的离心支撑盘（例如螺旋星系）。如果角动量被重新分配（由于合并和/或强烈的流出），星系的形态更有可能代表一个早期型或椭圆星系。虽然角动量在沿哈勃序列定位星系中的作用在z=0处得到了很好的约束，但重子角动量如何随宇宙时间演变，并导致高红移哈勃序列的出现还没有确定。哈勃太空望远镜（HST）的观测表明，从一个以块状、不规则形态为主的星系群向光滑的圆盘状星系的转变似乎发生在z=1.5左右，这被称为哈勃序列“出现”的时代。在这个项目中，我们将进行一个观测项目，测量z=1-3（即70 - 100亿年）星系样本的气体特性和恒星形成特性。我们将测量重子、暗物质、星系盘湍流以及气体流入和流出在确定星系形成过程中的作用。我们将讨论以下相互关联的问题：高红移星系盘的角动量是如何导致哈勃序列的出现的？2. 星系的暗物质部分是如何随着质量和红移而演化的？3. 什么物理过程控制着恒星形成区和气体盘的形成和演化？4. 形成恒星的风起源于哪里？它们携带多少质量和角动量？这是一个观察驱动的博士项目。成功的学生将使用一系列观测设施，可能包括前往智利、夏威夷或欧洲，为他们的论文获取数据。博士学位将提供成像还原和分析、积分场光谱学和干涉测量学方面的培训，也将有机会将观测结果与达勒姆正在开发的理论模型联系起来。

The Hubble-Sequence of galaxy morphologies remains one of the defining characteristics of galaxies, and provides one of the key constraints that galaxy formation models strive to reproduce. Dynamical studies of local galaxies have shown that the Hubble Sequence of galaxy morphologies follows a sequence of increasing angular momentum at a fixed mass. In the cold dark matter paradigm, galaxies form at the centres of dark matter halos. As the gas collapses within the dark halo, the baryons can both lose and gain angular momentum. If the angular momentum of the baryons is (weakly) conserved during collapse, they will form a centrifugally supported disk with an exponential light profile (e.g. a spiral galaxy). If the angular momentum is redistributed (due to mergers and/or strong outflows), the morphology of the galaxy is more likely to represent a early-type or elliptical galaxy. While the role of angular momentum in locating galaxies along the Hubble-Sequence is well constrained at z=0, how the baryonic angular momentum evolves with cosmic time, and results in the emergence of the Hubble-Sequence at high redshift has not been established. Observations from the Hubble Space Telescope (HST) have shown that the transition from a galaxy population dominated by clumpy, irregular morphologies to smoother, disk-like galaxies appears to occur around z=1.5, and this has been heralded as the epoch when the Hubble Sequence "emerged", In this project, we will conduct an observational program to measure the gas properties and star formation properties in a sample of galaxies at z=1-3 (i.e. lookback times of 7-10 billion years). We will measure the role of baryons, dark matter, disk turbulence, and gas inflows and outflows in defining the formation of the galaxies. We will address the following inter-related questions: 1. How does the angular momentum of high-redshift galaxy disks result in the emergence of the Hubble-Sequence? 2. How do the dark matter fractions of galaxies evolve with mass and redshift? 3. What physical processes control the formation and evolution of star-forming regions and the gas disk? 4. Where do star-forming winds originate and how much mass and angular momentum do they carry? This is an observationally-driven PhD project. The successful student will use a range of observational facilities, potentially including travel to Chile, Hawaii or Europe to obtain data for their thesis. The PhD will provide training in the reduction and analysis of imaging, integral field spectroscopy and interferometry There will also be opportunities to relate the observational results to theoretical models being developed at Durham.