PATT travel grant support for Bristol Astrophysics and Planetary Studies

布里斯托天体物理学和行星研究小组正在进行的项目需要使用世界上最大的望远镜进行仔细的观测。该提案要求为这些望远镜的旅行提供两年的资金，以便对无法远程运行的项目进行观测。在对微波背景辐射（宇宙大爆炸遗留下来的辐射）的研究中，重要的是要从前景辐射源中去除污染，这些污染会混淆我们对背景本身的测量。这些发射源是射电星系和类星体，它们可能比辐射本身要亮得多。消除这种污染需要使用美国和其他地方的大型射电望远镜对目标场的无线电环境进行敏感的观测。我们正在寻找的许多效应都与星系团中的气体在背景辐射上投下的“阴影”有关。然后，我们还需要用光学和红外望远镜研究这些星团，测量星团的质量，并深入了解星团在宇宙历史上是如何形成和变化的。我们对活动星系的研究主要是利用轨道x射线望远镜完成的，这些星系的核内有超大质量黑洞，但要了解发射的物理原理，还必须在无线电、红外和光学波段上绘制星系的地图。在这里，小组成员再次广泛使用大型地面望远镜，特别是美国的VLA，澳大利亚的ATCA和智利的ESO大型望远镜。这项工作的一个主要目的是了解活跃的星系如何将能量泵入宇宙中的气体中，从而帮助保持星系之间的气体温度。这些活跃星系的小规模模型可以在我们自己的银河系中找到，在质量是太阳质量几倍的黑洞系统中。研究这些星系的方法与研究活跃星系的方法相同，但需要重复观察这些系统，以跟踪它们在亮度和结构上的快速变化。从这些信息中，我们可以发现物质在黑洞附近的行为。我们工作的一个统一线索是对宇宙结构如何形成和随时间变化的研究。因此，我们的大部分观测都致力于寻找和描述最早的星系和星系团，然后看看这些系统与离我们更近的古老星系和星系团有何不同。同样，我们必须使用各种地面望远镜来完成这项工作，从射电望远镜到光学望远镜。大部分的光学工作都是由位于智利的ESO望远镜完成的。相应的无线电工作，探测来自低温气体的毫米波线，通常使用澳大利亚的ATCA或美国的GBT。与遥远的星系相比，我们可以更详细地研究附近的星系，我们还可以观察不同环境或不同红移下星系群的变化。我们对质量最低的星系特别感兴趣，它们是最常见的，但它们的特性却鲜为人知，而且与我们的星系非常不同。我们也研究我们自己的星系，观察恒星之间被超新星或年轻恒星加热的气体，以及发射相干（脉泽）辐射的致密气体团。气体运动告诉我们银河系的过程是如何不断地循环它的气体的，并且可以用来测量银河系内物体的距离。最后，我们试图了解太阳系中行星和大型卫星的大气特性——它们的形成和演化可以通过详细的光谱学来研究，我们使用了大型地面望远镜，如IRTF。

The Bristol Astrophysics and Planetary Studies groups work on programmes that require careful observations to be made using the world's largest telescopes. This proposal requests two years of funding for travel to those telescopes, to allow observing on projects that cannot be run remotely.In studies of the microwave background radiation, the left-over radiation from the Big Bang, it is important to remove contamination from foreground sources of emission that confuse our measurements of the background itself. These emission sources are radio galaxies and quasars, which may be much brighter than the radiation itself. Removal of this contamination requires sensitive observations of the radio environments of our target fields using large radio telescopes in the USA and elsewhere. Many of the effects that we are looking for relate to the "shadows" cast on the background radiation by the gas in clusters of galaxies. We then also need to study those clusters with optical and infra-red telescopes, to measure the cluster masses, and to gain insights into how clusters form and change over the history of the Universe.Our work on active galaxies, which host supermassive black holes in their nuclei, is principally done using orbiting X-ray telescopes, but to understand the physics of the emission it is essential also to map the galaxies in the radio, infra-red, and optical bands. Here again Group members make extensive use of large ground-based telescopes, particularly the VLA in the USA, the ATCA in Australia, and ESO's large telescopes in Chile. A major aim of this work is to understand how active galaxies pump energy into gas in the Universe, helping to keep the gas between the galaxies hot.Small-scale models of those active galaxies can be found in our own Galaxy, in black hole systems with masses a few times the mass of the Sun. Work on these systems is done in the same way as for the active galaxies, but with the extra need to observe the systems repeatedly to follow their rapid changes in brightness and structure. From such information we can discover how matter behaves near black holes.A unifying thread of our work is the investigation into how the stucture of the Universe forms and changes with time. A large fraction of our observing is therefore dedicated to finding and characterizing the earliest galaxies and clusters, and then seeing how these systems differ from their older counterparts that lie closer to us. Again, we have to use a wide range of ground-based telescopes for this work, from the radio to the optical. Much of the optical work is done with the ESO telescopes in Chile. The corresponding radio work, to detect mm-wave lines from cold gas, often uses the ATCA in Australia, or the GBT in the USA.Nearby galaxies can be studied in more detail than more distant ones, and we also look at the changing populations of galaxies in different environments or at different redshifts. We are particularly interested in galaxies of the lowest mass, which are the most common, but which have properties that are both poorly understood and rather different from galaxies like our own.We also study our own Galaxy, looking at the gas between the stars, which has been heated by supernovae or young stars, and at the dense lumps of gas that emit coherent (maser) radiation. The gas motions tell us about how processes in the Galaxy continually recycle its gas, and can be used to measure the distances of objects within our Galaxy. Finally, we seek to understand the properties of the atmospheres of planets and large satellites in our solar system - the formation and evolution can be studied by detailed spectroscopy, which we undertake using large ground-based telescopes such as the IRTF.