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。今天的星系是通过恒星形成和合并来增加恒星数量的。因此，对高红移星系中恒星形成速率的直接测量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，至少有一半的恒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。这样的观测对星系演化的设想尤为重要。近年来，远红外仪器SCUBA（以及随后的无线电观测）发现了许多恒星形成率非常高的星系，这一点在目前的模型中非常难以解释。LOFAR和欧空局的赫歇尔任务是为了在高红移的情况下研究这些模糊的恒星形成星系而设计的，这两个设施正在进行高调的调查项目。SCUBA的开创性调查结果是基于0.25平方公里范围内的几个星系。度。相比之下，赫歇尔河外遗产项目整理了1300度以上的数据，探测到100k远红外线星系，LOFAR深度调查将覆盖类似的区域。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），并提供具有统计意义的样本，以严格测试星系形成理论。这两项调查在天空的同一区域密切协调，因为这两项调查都通过不同的机制掩盖了恒星的形成。在苏塞克斯，我们正在开发新的贝叶斯工具（XID+）来经验地模拟星系调查数据。此外，还有一个新的调查项目LOFAR WEAVE，它使用WHT来获得LOFAR源的红移。该研究的目标将是(a)为最极端的亚毫米源提供LOFAR识别，这些源是打破理论的最高红移和高恒星形成率星系的候选者(b)利用XID+测试来进行众所周知的FIR/无线电相关的演化(c)扩展XID+与LOFAR WEAVE的光谱数据一起工作，确定最终的恒星形成率校准关系，并为未来更大的光谱调查做准备，如4MOST。

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.