Astrophysics Consolidated Grant 2022 - 2025

我们在天体物理学方面的研究包括宇宙学(研究宇宙)、最遥远的星系和系外行星(围绕其他恒星的行星)。这项工作将有助于回答人们可能提出的一些最大的问题，包括：我们能否在太阳系外找到生命的迹象？那么宇宙的命运是什么呢？我们的工作涉及理论、观察和实验室工作的结合。我们使用尖端的设施，如西蒙斯天文台和赫歇尔卫星，不久将使用欧几里德卫星、平方公里阵列和大型天气观测望远镜。此外，我们还测量了不同原子的精细的基本性质，这些性质是理论上无法预测的，以便与恒星中不同元素的观测进行比较。在过去的25年里，我们对宇宙本质的理解发生了深刻的变化，因为我们发现宇宙正在加速膨胀，而作为实验，主要是观察宇宙微波背景的实验，使得描述宇宙的参数-普通物质(原子)、暗物质和暗能量的比例以及当前的膨胀速度-得以准确测量。暗物质在引力下聚集，重量超过普通物质的五倍，但它的组成尚不清楚。更大的谜团是暗能量，它导致了宇宙的加速，并主导着质量能量预算。我们在宇宙学方面的工作采取了不同的方法来回答这些问题。但我们研究的共同主题是认识到，进步将通过更准确地测量数量(宇宙距离、膨胀率)的改进实验来实现。这些实验依赖于更好的技术(例如，测量宇宙微波背景的偏振)，以及更好的数据分析技术，以提高结果的精确度和准确度。后者是我们团队的一个特殊优势，它的形成是因为认识到了对宇宙数据集进行最佳分析的重要性，因为只有一个宇宙可以进行实验，而且尖端的实验非常昂贵。对人类来说，同样意义深远的是，在过去25年里，再次发现了围绕我们银河系中许多最近恒星的行星，并首次描述了其他恒星系统的特征。我们太阳系的类似物。如果最终目标是发现其他行星上的生命，这将通过不断进步来理解不同类型的行星(岩石/气体、大/小)是如何在不同的辐射分离条件下围绕不同类型的恒星(老/年轻、活跃/不活跃、热/冷)形成的，以及恒星在其生命周期中如何影响其行星上的条件。我们在这一领域的工作包括了解行星形成的机制的理论工作，以及对恒星可变性的更深层次的理解，以及这如何微妙地影响行星大气的测量(可能会导致错误的结论)。我们工作的第三个主题是对第一批星系和恒星的研究。随着我们在太空中向外看得更远，我们看到了过去的宇宙，因为光线到达我们所花费的时间。最终，我们将到达这样一个点，即我们在遥远的时间看到的，我们在星系刚形成时就发现了它们。我们通过红移来量化我们看到的距离有多远，红移是光在宇宙膨胀时的伸展。我们对最远的已知恒星形成的星系和类星体的研究探索了4到8的红移。为了更进一步，为了找到最早的恒星Ultima Thule，可能有15的红移，我们正在开发新的无线电技术，利用极微弱的氢的红移21厘米波长跃迁。

Our research in Astrophysics includes the areas of cosmology (thestudy of the Universe), the most distant galaxies, and exoplanets(planets around other stars). This work will make a contributiontowards answering some of the greatest questions that can be posed,including: can we find signs of life outside the solar system? andwhat is the fate of the Universe? Our work involves a combination oftheory, observations, and laboratory work. We use cutting-edgefacilities such as the Simons Observatory and the Herschel satellite,and soon the Euclid satellite, the Square Kilometre Array,and the Large Synoptic Survey Telescope. In addition we measure in thelaboratory fundamental properties of different atoms, properties thatcannot be predicted theoretically, for comparison against observationsof the different elements in stars.Our understanding of the nature of the Universe has changed profoundlyover the past 25 years, since it was discovered that the expansion ofthe Universe is accelerating, and as experiments, primarily thoseobserving the cosmic microwave background, have allowed the accuratemeasurement of the parameters describing the Universe - theproportions of ordinary matter (atoms), dark matter, and dark energy,and the current rate of expansion. Dark matter clumps gravitationallyand outweighs ordinary matter by a factor five, but what it consists ofis unknown. The even greater mystery is dark energy, which is causingthe acceleration of the Universe, and which dominates the mass-energybudget. Our work in cosmology takes different approaches to answeringthese problems. But the common theme in our research is theunderstanding that advances will come through improved experimentsthat measure quantities (cosmological distances, the rate ofexpansion) more accurately. The experiments rely on better technology(e.g. measurements of polarisation of the cosmic microwavebackground), and better data analysis techniques that improve theprecision and accuracy of the results. The latter is a particularstrength of our team, which has been shaped in recognition of the importance of the optimal analysis of cosmologicaldatasets, given that there is only one universe to experiment on, andthat cutting edge experiments are very costly.No less profound for humankind has been the discovery, again over thepast 25 years, of planets around many of the nearest stars in ourgalaxy, and the first characterisation of other stellar systemsi.e. analogues of our solar system. If the ultimate goal is todiscover life on other planets, this will be achieved throughsuccessive advances in understanding how different types of planet(rocky/gaseous, large/small) form around different types of star(old/young, active/inactive, hot/cool) at different radialseparations, and of how the star over its lifetime can affect theconditions on its planets. Our work in this area includes theoreticalwork to understand the mechanisms by which planets form, as well asdeveloping a deeper understanding of stellar variability and how thiscan subtly bias measurements of the atmospheres of planets (possiblyleading to erroneous conclusions).The third theme in our work is the study of the first galaxies and stars. As welook out further in space we see the Universe as it was in the past,because of the time light has taken to reach us. Eventually we willreach the point where we are seeing so far back in time that we findgalaxies when they first formed. We quantify how far back we see bythe redshift, the stretching of light by the expansionof the Universe. Our studies of the most distant knownstar-forming galaxies and quasars explore redshifts of 4 to 8. To reacheven further, to find the very first stars, ultima Thule, maybe atredshifts of 15, we are developing new radio techniques,exploiting the extremely faint redshifted 21cm wavelengthtransition of hydrogen.