Using Cosmic Beasts To Uncover The Nature Of Dark Matter

到目前为止，天文学家只观测到宇宙中5%的物质：发光（或重子）物质。剩下的95%是看不见的，由所谓的暗物质和暗能量组成。暗物质和暗能量的性质是现代物理学中最紧迫的基本问题之一。我们宇宙的这个黑暗区域仍然不可能直接探测到，因为这两种成分都不与标准物质粒子相互作用。此外，许多理论预测暗物质在地面实验中基本上无法检测到，只能通过天体物理实验室进行探测。如果这些理论是正确的，暗物质只能在它聚集到足够的数量，使其引力影响我们可以看到的周围事物的地方进行研究。我提议追踪星系团中暗物质的行为（宇宙中最大的可观测结构，也被称为“宇宙野兽”），以区分3种主要模型：冷，热和自相互作用的暗物质。我的FLF项目利用了过去十年世界上最大的望远镜对星系团的观测急剧增加，反映了该领域的首要目标。我在哈勃太空望远镜上获得了最大类别的观测时间（>100个轨道），以获得有史以来最深的星团周围环境成像，加上地球上最大的望远镜（VLT）的后续光谱学。我设计这些观测是为了通过“引力透镜”效应来绘制星系团的暗物质，引力透镜会扭曲和放大星系团后面的物体。我使用这些数据（i）自己，（ii）校准最大的（但浅）哈勃成像（iii）设置议程，并优化设施，如欧几里得，雅典娜和詹姆斯韦伯太空望远镜通过2020s.Cosmological模拟表明，星系团是最好的实验室来区分暗物质的模型，因为它们仍在增长。团簇通过彼此合并而成长;每一次合并都像一个巨大的粒子对撞机。暗物质的性质可以通过其碰撞轨迹来揭示，碰撞轨迹应该介于恒星和（氢）气体之间。恒星和氢的性质已经被很好地理解，因此它们限制了暗物质的测量。传统的研究计划通常将暗物质、恒星和气体的测量分开，因为它们需要从不同的望远镜（红外、紫外、X射线）进行观测。我开发了一种多波长分析方法，使以前不可能的测量成为可能，例如暗物质和气体进入星系团的时间尺度，星系团达到平衡的速度，以及可能的暗物质粒子相互作用的限制。我还领导建立了一个新的研究领域，自我的FLF开始以来，我已经扩大了这个领域。当短暂的事件（如超新星爆炸）发生在星系团后面时，来自爆炸的光可以被引力透镜化，并沿着沿着多条视线可见。测量超新星多重成像之间的时间延迟，可以提高绘制星团暗物质的分辨率。我特意安排了我的HST和VLT观测，以便能够发现和监测这些事件。它们还提供了发现引力透镜波的电磁对应物的（高风险/高回报）可能性，这是一个新领域，我们的团队通过开发理论框架和观测策略来探测第一个引力透镜引力波，已经成为领导者。它使用我的高精度技术来分析大数据，并在达勒姆最先进的宇宙学模拟的世界领先的理论框架内进行解释。

Astronomers have only observed 5% of the content of the Universe so far: the luminous (or baryonic) matter. The remaining 95% is invisible, consisting of so-called Dark Matter and Dark Energy. The nature of dark matter and dark energy is one of the most pressing fundamental questions in modern physics. This Dark Sector of our Universe has remained impossible to detect directly, because neither component interacts with standard matter particles. Moreover many theories predict dark matter will remain fundamentally undetectable in terrestrial experiments, and can only be probed by astrophysical laboratories. If these theories are correct, dark matter can only be studied where it gathers in sufficient quantities for its gravity to affect things around it we can see. I propose to track the behaviour of dark matter in galaxy clusters (the most massive observable structures in the universe, also called 'cosmic beasts'), to distinguish between the 3 leading models: cold, warm and self-interacting dark matter.My FLF project exploits a dramatic increase over the past decade in observations of galaxy clusters by the world's biggest telescopes, reflecting the field's recognition as a top priority goal. I got awarded observing time on the Hubble Space Telescope in the largest category of programme (>100 orbits) to obtain the deepest ever imaging of clusters' surroundings, plus follow-up spectroscopy from the largest telescope on Earth (VLT). I designed these observations to map clusters' dark matter, via the effect of 'gravitational lensing', which distorts and magnifies objects behind the cluster. I use these data (i) by themselves, (ii) to calibrate the largest (but shallow) Hubble imaging (iii) to set the agenda for, and optimise facilities like Euclid, Athena and the James Webb Space Telescope through the 2020s.Cosmological simulations indicate that galaxy clusters are the best laboratories to distinguish between models of dark matter, because they are still growing. Clusters grow by merging with each other; every merger acts like a gigantic particle collider. The properties of dark matter are revealed by its trajectory through a collision, which should be between that of stars and of (hydrogen) gas. The properties of stars and hydrogen are well understood, so they bookend measurements of dark matter.Traditional research programmes usually separate measurements of dark matter, stars and gas, because they require observations from different (infrared, ultraviolet, X-ray) telescopes. I have developed a multiwavelength analysis, to enable previously impossible measurements such as the time-scale on which dark matter and gas are funneled into clusters, how quickly clusters reach equilibrium, and constraints on possible dark matter particle interactions.I have also led the establishment of a new research area, which I have expanded since the start of my FLF. When transient events (such as supernova explosions) happen behind a galaxy cluster, light from the explosion can be gravitationally lensed and visible along more than one line of sight. Measuring the time delay between multiply-imaged versions of a supernova increases the resolution with which the cluster's dark matter can be mapped. I intentionally scheduled my HST and VLT observations to enable the discovery and monitoring of such events. They also offer the (high risk/high reward) possibility of discovering electromagnetic counterparts to lensed gravitational waves, a new field in which our team has become a leader by developing the theoretical framework and observational strategy to detect the first gravitationally lensed gravitational wave.My UKRI FLF research programme exploits the latest multiwavelength data from world-class facilities. It uses my high-precision techniques to analyse big data, and is interpreted within the world-leading theoretical framework of Durham's state-of-the-art cosmological simulations.