Short-term visitors programme for Bristol Astrophysics

布里斯托天体物理学小组集中研究宇宙中最大尺度物体的起源、生长和结构：星系和星系团。该小组使用无线电，红外线，光学和X射线望远镜进行调查，以寻找年轻的星系和高红移的星系团-这意味着这些物体在宇宙中非常遥远，并且在过去很长一段时间内被看到，当它们年轻时。对这些年轻天体的研究应该比对离我们更近（因此更老）的星系和星系团的研究更能证明它们是如何形成的。年轻的天体如何发展成我们今天看到的星系团和星系的问题也很重要，在这里，与气体流动、星系和星系团碰撞以及黑洞释放的能量有关的复杂物理学似乎也很重要。有时，一些罕见的事件，比如所谓的“活跃”星系的爆发或重大碰撞，会戏剧性地改变星系和星系团的性质。在这些事件之间，较慢的过程允许星系和星系团回到一个几乎稳定但最终不稳定的状态。由于物理学是复杂的，我们正在从事许多项目，旨在解开问题，并了解什么过程是最重要的，以及它们的后果是什么。由于布里斯托天体物理学小组规模很小，因此与合作者密切合作研究这些复杂问题是很重要的。因此，小组的来访者对小组的研究非常重要，本提案要求提供资金，以便将合作者带到布里斯托与小组成员合作。与此同时，这有助于扩大天体物理学的范围，其中集团的研究生和博士后研究人员接触，并转移到我们的合作者的机构的想法。

The Bristol Astrophysics Group has concentrated its research on the origins, growth, and structure of the largest-scale objects in the Universe: galaxies and clusters of galaxies. The Group conducts surveys using radio, infra-red, optical, and X-ray telescopes to search for young galaxies and clusters at high redshift - which means that the objects are both very distant in the Universe, and are being seen a long time in the past, when they were young. Studies of these young objects should then show more evidence of how they formed than studies of galaxies and clusters closer to us (and hence older). The question of how the younger objects develop into the clusters and galaxies that we see today is also important, and here it appears that much complicated physics to do with gas flows, galaxy and cluster collisions, and the energy release from black holes is relevant. Sometimes rare events, such as outbursts from so-called 'active' galaxies or major collisions, change the properties of the galaxies and clusters dramatically. In between these events, slower processes allow the galaxies and clusters to settle back towards an almost-steady, but ultimately unstable, state. Since the physics is complicated, we are engaged in many projects aiming to disentangle the problems and understand what processes are most important, and what are their consequences. Because the Bristol Astrophysics Group is small, it is important that it works closely with its collaborators to study these complicated problems. Visitors to the Group are, therefore, of great importance to the research of the Group, and this proposal requests funding to bring collaborators to Bristol to work with Group members. At the same time, this helps to extend the range of astrophysics to which Group research students and post-doctoral research fellows are exposed, and transfers ideas to our collaborators' institutions.