Star-forming Galaxies in the Distant Universe with Herschel and LOFAR

天体物理学的一个关键目标是了解星系的形成和演化。今天的星系通过恒星的形成和合并来增加它们的恒星数量。因此，直接测量高红移星系中的恒星形成率是推进我们对这些过程的理论理解的关键组成部分。然而，在高红移时，至少有一半的星星形成活动被尘埃遮蔽，只能通过远红外（FIR）和无线电波长的观测来探测。这样的观测对于星系演化的情景特别重要。近年来，远红外仪器SCUBA（以及随后的射电观测）发现了许多具有非常高的恒星形成率的星系，这些星系极难用现有模型解释。LOFAR和欧空局的Herschel使命旨在研究这些高红移的模糊恒星形成星系，这两个设施正在进行高姿态的调查项目。使用SCUBA进行调查的开创性结果是基于0.25平方英尺区域内的几个星系。度相比之下，赫歇尔河外遗产项目收集了1300度以上的数据，探测到10万个远红外星系，而LOFAR深度巡天将覆盖类似的区域。这些区域是必要的，以涵盖星系环境的全部范围（从星团到空洞），并提供统计上重要的样本，以严格测试星系形成理论。这两次巡天在天空的同一区域密切协调，因为两次巡天都是通过不同的机制探测模糊的恒星形成。在苏塞克斯，我们正在开发新的贝叶斯工具（XID+），以经验模型星系调查数据。此外，将有一个新的调查项目LOFAR WEAVE，它使用WHT来获得LOFAR源的红移。学生奖学金的目标是：（a）为最极端的亚毫米级源提供LOFAR识别，它们是理论上突破的最高红移和高恒星形成率星系（B）的候选者，可以利用XID+测试在众所周知的FIR/射电相关中进行演化（c），以扩展XID+使用LOFAR WEAVE的光谱数据，确定明确的星星形成率校准关系，并为未来更大规模的光谱调查（如4 MOST）做准备。

A key goal in astrophysics is to understand galaxy formation and evolution. Galaxies today have built up their stellar populations by star-formation and merging. Therefore direct measurements of the star-formation rates in galaxies at high redshift are a key component in advancing our theoretical understanding of those processes. However, at high redshift at least half of the star formation activity is obscured by dust and can only be probed by observations at far infrared (FIR) and radio wavelengths. Such observations are particularly critical for galaxy evolution scenarios. This was notably demonstrated in recent years by the famous discovery by the far infrared instrument SCUBA (and subsequent radio observations) of numerous galaxies with very high star-formation rates that are extremely hard to explain by current models. LOFAR and ESA's Herschel mission were designed for studying these obscured star-forming galaxies at high redshift and high profile survey projects are being carried out by both facilities. The pioneering results from surveys with SCUBA are based on few galaxies over areas of 0.25 sq. degrees. In contrast the Herschel Extragalactic Legacy Project collates date over 1300 deg^2 degrees detecting 100k far infrared galaxies and the LOFAR Deep survey will cover similar areas. These areas are necessary to cover the full range of galaxy environments (from clusters to voids) and to provide statistically significant samples to rigorously test galaxy formation theories. These two surveys are closely coordinated in the same regions of the sky since both probe obscured star-formation but through different mechanisms. At Sussex we are developing new Bayesian tools (XID+) to empirically model galaxy survey data. In addition there will be a new survey project LOFAR WEAVE which uses WHT to get redshifts for LOFAR sources. The objective of the studentship will be (a) to provide LOFAR identifications for the most extreme sub-mm sources, which are candidates for the theory-busting highest redshift and high star-formation rate galaxies (b) to exploit XID+ test for evolution in the well-known FIR/radio correlation (c) to extend XID+ to work with the spectral data from LOFAR WEAVE and determine definitive star formation rate calibration relations and prepare for larger spectroscopic surveys in the future such as 4MOST.