PATT travel grant support for the Bristol Astrophysics Group

布里斯托尔天体物理学小组致力于一些项目，这些项目需要使用世界上最大的望远镜进行仔细的观测。这项提案要求提供两年的资金，用于前往那些不能远程运行的望远镜。在研究微波背景辐射，即大爆炸遗留下来的辐射时，重要的是去除前景发射源中的污染，这些污染源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亮得多。因此，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我们的目标领域的射电环境进行灵敏的观测。我们正在寻找的许多效应都与星系团中气体投射在背景辐射上的“阴影”有关。然后，我们还需要用光学和红外线望远镜研究这些星系团，测量星系团的质量，并洞察星系团的形成和在宇宙历史上的变化。我们对活动星系的研究主要是使用轨道X射线望远镜完成的，但为了了解发射的物理原理，我们还必须绘制射电、红外线和光学波段的星系图。活动星系的核心是超大质量黑洞。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动星系如何将能量输送到宇宙中的气体中，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。对这些系统的研究与对活动星系的工作相同，但额外需要反复观察这些系统，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主线是调查宇宙的结构是如何形成和随时间变化的。因此，我们观测的很大一部分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较老的系统有什么不同。同样，我们必须使用从无线电到光学的广泛的地面望远镜来完成这项工作。大部分光学工作是由智利的欧洲南方天文台望远镜完成的。相应的无线电工作，探测来自冷气体的毫米波谱线，在澳大利亚通常使用ATCA，在美国使用GBT。与更远的星系相比，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时星系数量的变化。我们对质量最低的星系特别感兴趣，这是最常见的星系，但它们的性质既鲜为人知，又与我们自己的星系有很大不同。最后，我们还研究了我们自己的银河系，观察了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)辐射的致密气体块。气体的运动告诉我们银河系中的过程如何不断地循环其气体，并可以用来测量我们银河系内物体的距离。

The Bristol Astrophysics Group works on a number of 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, where they 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. Thus 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. Finally, 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.