BRIdging Disciplines of Galactic Chemical Evolution (BRIDGCE): The Rise of the Chemical Elements

该联盟的主要科学目标是通过使用化学元素作为恒星和星系中发生的过程的指纹，来研究从大爆炸到现在的宇宙化学演化。尽管光可以传播数十亿年，我们现在可以观察到复合时代发出的宇宙微波背景，但早期宇宙中形成的大多数恒星早已死亡，像第一个光晕这样更大的结构已经合并或被破坏。因此，直接观察它们是不可能的。幸运的是，恒星和星系结构在由其灰烬形成的恒星中留下了化学指纹。因此，在极贫金属(EMP)恒星中，这些恒星的质量低到足以比宇宙目前的年龄更长，我们可以观察到发生在早期宇宙中的过程的化学指纹。此外，我们可以通过将恒星的理论模型与银河系光晕中EMP恒星的观测结果进行比较，以及通过在宇宙学上有效的模拟中生成星系化学演化的模型来限制它们的性质。此外，通过模拟从早期宇宙到现在的恒星和银河系化学演化，我们可以再现星系，特别是银河系的整个化学史。我们的研究还解决了其他关键的科学问题：“我们如何探索和理解宇宙的极端？”通过研究和限制超新星爆炸的性质，以及“核物质和强子物质的性质是什么？”通过提高我们对核反应速率的了解。这些与化学元素的兴起有关的研究构成了拟议研究的主要科学目标。要回答这样的问题：“早期宇宙的性质是什么？我们的元素是从哪里产生的？”，天体物理和核物理的各个学科的知识是必要的。事实上，核数据(特别是核反应速率)是恒星演化模型的关键输入，因为核反应为恒星提供能量。这些信息决定了恒星的寿命，以及它们最终喷出物的组成。反过来，恒星通过它们辐射的光线、它们强大的超新星爆炸以及它们产生的所有化学元素，向它们所属的星系提供重要的反馈。因此，恒星演化模型的输出是星系化学演化模型的关键组成部分。这些模型跟踪恒星形成的连续事件，并追踪不同星系中元素的富集史。然后，可以将模型预测与对EMP恒星的观测进行比较，这些观测携带着在其诞生之前累积的化学富集物的化学指纹。因此，与观测结果进行比较可以同时限制星系和恒星的性质。恒星演化模型还可以用作虚拟核物理实验室，在其中我们可以测试某些核反应速率中的不确定性的影响。为了回答这些问题，这个联合体将采用多学科方法，从英国五所大学的世界领先科学家那里收集专业知识，并将进一步加强其与开发和生产粒子探测器和高科技共享存储器计算机硬件的公司的现有跨部门联系。我们的研究将在不同学科中应用创新技术，并通过对应于三个不同物理尺度的四个项目来应对这一科学挑战：-银河系和银河系外尺度(项目A)-恒星及其核合成(项目B)-微观物理：对核和恒星模型不确定性的敏感性(项目C)以及恒星环境对核反应速率和恒星演化的影响(项目D)

The main scientific goal of this consortium is to study the chemical evolution of the universe from the Big Bang up to now by using chemical elements as fingerprints of the processes that took place in stars and galaxies. Although light can travel for billions of years and we can nowadays observe the cosmic microwave background emitted at the epoch of recombination, most of the stars that formed in the early universe are long dead, and larger structures like the first halos have merged or been disrupted. It is therefore not possible to observe them directly. Fortunately, stars and galactic structures leave chemical fingerprints in the stars that formed out of their ashes. Thus, in extremely-metal-poor (EMP) stars that have a low enough mass to live longer than the current age of the universe, we can observe the chemical fingerprints of the processes that took place in the early universe. Moreover, we can constrain their properties by comparing theoretical models of stars with observations of EMP stars in the halo of our galaxy, and by generating models of the chemical evolution of galaxies in cosmologically-valid simulations. Furthermore, by simulating stellar and galactic chemical evolution from the early universe until the present day, we can reproduce the entire chemical history of galaxies and the Milky Way in particular. Our research also addresses other key scientific questions: ``How can we explore and understand the extremes of the universe?'' by studying and constraining the properties of supernova explosions and ``What is the nature of nuclear and hadronic matter? '' by improving our knowledge of nuclear reaction rates. These studies linked to the rise of the chemical elements constitute the main scientific goals of the proposed research.To answer questions like: "What are the properties of the early universe?, Where were the elements we are made of created?", knowledge in various disciplines of astrophysics and nuclear physics is necessary. Indeed, nuclear data (nuclear reaction rates in particular) are a key input for stellar evolution models since nuclear reactions provide the energy that powers stars. This information determines stellar lifetimes, and the composition of their final ejecta. Stars, in turn, provide important feedback into the galaxies they belong to through the light they radiate, their powerful supernova explosions and all the chemical elements they produce. The outputs of stellar evolution models are therefore key ingredients for galactic chemical evolution models. These models follow successive episodes of star formation and trace the history of the enrichment of the elements in various galaxies. The model predictions can then be compared to observations of EMP stars that carry the chemical fingerprints of the cumulative chemical enrichment that preceded their birth. Comparison to observations can thus constrain both the galactic and stellar properties. Stellar evolution models can also be used as virtual nuclear physics laboratories, in which we can test the impact of uncertainties in certain nuclear reaction rates. To answer these questions, this consortium will adopt a multidisciplinary approach, gathering expertise from world-leading scientists at five UK universities, and will also further its existing intersectoral links with companies developing and producing particle detectors and high-tech shared-memory computer hardware.Our research will apply innovative techniques across different disciplines and attack this scientific challenge through 4 projects corresponding to 3 different physical scales:- Galactic and extra-Galactic scales (Project A)- Stars and their nucleosynthesis (Project B)- Micro-physics: sensitivity to nuclear and stellar modelling uncertainties (Project C) and the impact of stellar environments on nuclear reaction rates and stellar evolution (Project D)