Unveiling the Hidden Universe - From the First Galaxies to Brown Dwarfs

我们提出了一个使用三种革命性新仪器的科学方案。普朗克探测器将绘制宇宙微波背景辐射图。赫歇尔空间天文台和詹姆斯·克拉克·麦克斯韦望远镜上的SCUBA-2照相机将在亚毫米波波段观测宇宙，这一波段很大程度上仍未被探索过，可能蕴藏着恒星和星系起源问题的答案。当然，这些问题是天文学中最大的两个问题，我们还没有很好的答案的原因是星际尘埃，星际尘埃是充满星际空间的微小固体颗粒，像烟雾一样，隐藏了可见光。这种尘埃是研究恒星和星系形成的一个特殊问题，因为恒星和星系的形成发生在有大量气体和尘埃的区域，因此，例如，最年轻的恒星是完全隐藏在普通光学望远镜的视野之外的。幸运的是，尘埃被吸收的光辐射加热，然后发出亚毫米辐射，因此通过观察亚毫米辐射，我们可以研究被尘埃隐藏的物体。我们的小组将使用赫歇尔和SCUBA-2进行一些大型项目，以调查恒星和星系的起源。例如，我们正在领导一个项目，利用SCUBA-2观测古尔德带（Gould Belt）中最年轻的恒星。古尔德带是一圈附近的分子云，是环绕天空的恒星的诞生地。我们也是国际团队的一部分，他们将使用赫歇尔来研究同样的分子云，并在这个波段绘制银河系的大部分地图。我们将使用另一种观测技巧来研究星系的起源和演化：事实上，由于光速有限，我们在观察太空的同时也在回顾过去。在四个巨大的赫歇尔项目中，其中三个由我们领导，我们将研究从附近宇宙中的星系到100亿光年外的星系，这将使我们能够研究100亿年宇宙历史中星系的演化，尤其是它们的诞生。最后，在赫歇尔的另一个项目中，我们将研究尘埃本身的起源，并确定尘埃是在老恒星的大气中形成的，还是在超新星中形成的，超新星是一种巨大的爆炸，结束了大质量恒星的生命。我们还将开展一套平行的理论方案来解决这些问题。例如，我们将对恒星和恒星前核的形成进行计算机模拟，恒星前核是分子云中密度最大的部分，也是恒星真正形成的地方。任何计算机模拟都必须建立在许多关于恒星形成方式的假设之上，通过将模拟的预测与我们的SCUBA-2和赫歇尔调查的结果进行比较，我们将检验这些假设是否正确。普朗克探测器将把时间机器的把戏扩展到大爆炸后40万年，也就是宇宙背景辐射发射的时候。因为这种辐射已经沿直线传播了近140亿年，它在天空中的变化揭示了当时宇宙中存在的密度的微小差异——这些差异最终在140亿年之后（以及在这一时期的重力作用）变成了我们今天看到的块状宇宙。我们将以两种方式利用这个窗口来了解早期宇宙。首先，利用我们开发的一些新的统计技术，我们将利用宇宙背景辐射的特性来确定我们所生活的宇宙的类型。其次，通过研究丰富的星系团中气体对这种辐射的散射，我们将研究过去140亿年星系团的演化。

We propose a scientific programme that uses three revolutionary new instruments. The Planck Surveyor will map the cosmic microwave background radiation. The Herschel Space Observatory and the SCUBA-2 camera on the James Clerk Maxwell Telescope will observe the universe in the submillimetre waveband, which is still largely unexplored and which probably holds the answers to the questions of the origins of the stars and galaxies. These questions, of course, are two of the biggest ones in astronomy, and the reason we don't yet have very good answers is interstellar dust, the tiny solid particles that fill interstellar space and which, like smoke, hide optical light. This dust is a particular problem in studying the formation of stars and galaxies, which happens in regions where there are especially large amounts of gas and dust - and so the youngest stars, for example, are completely hidden from the view of normal optical telescopes. Fortunately, the dust is warmed by the absorbed optical radiation and then emits submillimetre radiation, and so by observing the submillimetre radiation we can study the objects that are hidden by the dust. Our group will use Herschel and SCUBA-2 for a number of large projects to investigate the origin of stars and galaxies. For example, we are leading a project to use SCUBA-2 to observe the youngest stars in the Gould Belt, a ring of nearby molecular clouds, the birthplaces of stars, that circles the sky. We are also part of international teams that will use Herschel to study the same molecular clouds and also to map a large part of the Milky Way in this waveband. We will study the origin and evolution of galaxies using another observational trick: the fact that by looking out into space we are also, because of the finite speed of light, looking back in time. In four huge Herschel projects, three of which we are leading, we will study galaxies from ones in the nearby universe to ones ten billion light years away, which will allow us to study the evolution of galaxies over ten billion years of cosmic history, and especially their birth. Finally, in another Herschel project, we will study the origin of the dust itself, and determine whether dust is formed in the atmospheres of old stars or whether it is formed in supernovae, the colossal explosions that end the lives of massive stars. We will also carry out a set of parallel theoretical programmes to address these questions. For example, we will carry out computer simulations of the formation of both stars and of prestellar cores, which are the densest parts of molecular cloud and the places where the stars actually form. Any computer simulation is necessarily built on a number of assumptions about the way in which stars form, and by comparing the predictions of the simulations with the results of our SCUBA-2 and Herschel surveys, we will test whether these assumptions are correct. The Planck Surveyor will extend the time-machine trick to a time only 400,000 years after the big bang, which is when the cosmic background radiation was emitted. Because this radiation has been travelling in a straight line for almost 14 billion years, its variation over the sky reveals the tiny differences in density that existed in the universe at this time - differences that eventually after 14 billion years (and the effect of gravity acting during this period) turned into the lumpy universe we see around us today. We will use this window into the early universe in two ways. First, using some new statistical techniques we have developed, we will use the properties of the cosmic background radiation to determine the type of universe we live in. Second, by studying the scattering of this radiation by the gas in rich clusters of galaxies, we will study the evolution of clusters over the last 14 billion years.