Astrophysics Consolidated Grant 2022 - 2025

我们在天体物理学的研究包括宇宙学（宇宙的研究），最遥远的星系和系外行星（其他恒星周围的行星）的领域。这项工作将有助于回答一些可能提出的最大问题，包括：我们能在太阳系外找到生命的迹象吗？宇宙的命运是什么？我们的工作包括理论、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，很快还有欧几里得卫星、平方公里阵列和大型综合巡天望远镜。此外，我们在实验室测量不同原子的基本性质，这些性质在理论上无法预测，以与恒星中不同元素的观测进行比较。我们对宇宙性质的理解在过去的25年里发生了深刻的变化，因为人们发现宇宙的膨胀正在加速，作为实验，主要是那些观察宇宙微波背景辐射的实验，已经允许精确测量描述宇宙的参数-普通物质（原子），暗物质和暗能量的比例，以及当前的膨胀率。暗物质因引力而聚集，其质量是普通物质的五倍，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，并主导着质能收支。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理解进步将通过更精确地测量数量（宇宙学距离，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）和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，我们的团队是在认识到对宇宙学数据集进行最佳分析的重要性的基础上组建的，因为只有一个宇宙可以进行实验，而尖端实验的成本非常高。对人类来说意义同样深远的是，在过去的25年里，我们再次发现了银河系中许多离我们最近的恒星周围的行星，和其他恒星系统的第一个特征。类似于我们的太阳系。如果最终目标是在其他行星上发现生命，这将通过理解不同类型的行星（岩石/气体，大/小）如何在不同类型的星星（老/年轻，活跃/不活跃，热/冷）周围以不同的径向距离形成，以及星星在其一生中如何影响其行星上的条件来实现。我们在这一领域的工作包括理解行星形成机制的理论工作，以及对恒星变化的深入理解，以及这如何微妙地影响行星大气的测量（可能导致错误的结论）。我们工作的第三个主题是研究第一个星系和恒星。当我们在太空中看得更远时，我们看到的宇宙就像过去一样，因为光到达我们需要时间。最终，我们将到达一个点，我们看到这么远的时间，我们发现星系时，他们第一次形成。我们通过红移来量化我们所看到的距离，宇宙膨胀导致的光的拉伸。我们对已知最遥远的恒星形成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，可能是红移15，我们正在开发新的无线电技术，利用氢的极其微弱的红移21厘米的波长跃迁。

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.