Galaxy-scale jets with new extragalactic radio surveys

众所周知，来自超大质量黑洞的河外喷流在星系演化过程中扮演着重要角色。在过去的十年里，这一领域的研究主要集中在丰富星系团中心的强大喷流上，在那里，喷流似乎控制着大质量星系中的恒星形成--这个过程现在被纳入了大多数星系形成的宇宙学模拟中。但是，正如我们从最近测量星系冲击影响的X射线研究中发现的那样，宿主星系中包含的较小的喷流也可以对单个星系的规模产生强大的影响(例如Croston等人)。2007年、2009年，Mingo等人。2011年，2012年，Heesen等人。2014年)。它们的射电光度低，体积小，这意味着在以前的射电调查中很难识别这些喷气式飞机。出于这个原因，人口的人口统计数据，以及这些小规模喷流在高红移宇宙中的作用，还没有被理解。同样，通过X射线跟踪直接测量它们的影响只有少数几个物体可能。这个项目将涉及利用LOFAR(低频阵列)对河外天空进行新的低频测量，该阵列具有识别和表征星系规模喷流的灵敏度、分辨率和图像保真度。通过将这个群体与其他波长的数据进行交叉匹配，就有可能回答关于它们有多常见，以及它们的射电性质与它们的黑洞质量、吸积行为和环境有何关系的问题。还有可能进行新的和存档的X射线观测，以测量单个物体的冲击波特性。

Extragalactic jets from supermassive black holes are known to play an important role in the process of how galaxies evolve. Research in this area over the last decade has focused particularly on powerful jets in the centres of rich galaxy clusters, where jets appear to regulate star formation in massive galaxies - a process now incorporated into most cosmological simulations of galaxy formation. But smaller jets contained within their host galaxies can also have a powerful effect on the scale of individual galaxies, as we have found from recent X-ray studies measuring the impact of their shocks (e.g. Croston et al. 2007, 2009, Mingo et al. 2011, 2012, Heesen et al. 2014). Their low radio luminosity and small size mean that these jets have been difficult to identify in previous radio surveys. For this reason, the demographics of the population, and the role of these small-scale jets in the high-redshift Universe, are not understood. Similarly, direct measurements of their impact via X-ray follow up have only been possible for a handful of objects.This project will involve exploiting new low-frequency surveys of the extragalactic sky with LOFAR (the Low-Frequency Array), which have the sensitivity, resolution and image fidelity to identify and characterize galaxy-scale jets. By cross-matching this population with data at other wavelengths, it will be possible to answer questions about how common they are, and how their radio properties relate to their black hole mass, accretion behaviour and environment. There is also the possibility to work on new and archival X-ray observations to measure shock properties in individual objects.