INvestigating Stellar Populations In RElics (INSPIRE)

研究遗迹中的恒星群(INSPIRE)是理解宇宙中最大质量的星系--巨型椭圆星系早期组装的革命性方法。这一点非常重要，因为这个天体家族包含了我们宇宙中超过一半的恒星和大部分化学元素。巨大的椭圆体被认为是通过两个阶段的过程形成的。在宇宙生命的早期，一个强烈的、短暂的恒星形成过程创造了致密和大质量的天体(“红块”)。然后，在第二个更延长时间的阶段，红金块与其他星系合并，或者气体落入其中形成新的恒星。这导致了体积的戏剧性增长，并将红块转变为我们今天观察到的巨大的巨大椭圆星系。不幸的是，在局部椭圆体中，这种二次“吸积”物质污染了编码质量组装第一阶段信息的“原始”成分。这无可救药地阻碍了我们对宇宙结构形成的早期阶段的研究。幸运的是，一些红金块在它们的一生中不会与任何其他结构结合，因此在宇宙时间里继续它们孤立的路径，而不会增加尺寸，更重要的是，不会改变它们的恒星含量。这些孤零零的红块比当地的椭圆形小6倍，密度高100倍。它们在时间上被冻结，因此被称为古代宇宙的“遗物”；研究它们就像考古学家向恐龙化石学习一样。遗迹包含最古老的恒星，因此有可能揭开我们对宇宙中非常早期的结构形成的理解。但是每个时代有多少遗迹呢？它们如何在没有经历任何与其他系统相互作用的情况下被动地在宇宙时间中进化？他们是在什么样的环境中优先被发现的？这些问题是我成功的研究提案的核心，该提案使用了欧洲南方天文台的前沿设施。根据已经获得的最大样本超致密大质量星系的高质量光谱，我将测量它们的年龄，以确认它们是与宇宙一样古老的遗迹。我将全面描述这些星系中的恒星，以揭示遗迹最初是如何形成的，以及它们是如何变化的，如果有的话。由于遗迹是本地巨型椭圆体的“种子”，我的研究将彻底改变我们对推动当今宇宙中最大质量星系最初组装的过程的理解。将INSPIRE数据与公开可用的大范围天空测量数据进行匹配，我将能够详细研究优先发现文物的环境。这对于理解宇宙中密度最高、密度最高的物体是如何形成的，以及它们如何演化成局部椭圆体至关重要。我还将把我的观测结果与整个宇宙的计算机模拟进行比较。每个时期遗迹的数量及其通过模拟预测的特征取决于它们用来再现星系大小增长的成分(例如，给定星系与其他物体相互作用的次数)。最后，由于新的成像和光谱数据具有从地面可以达到的最高空间分辨率，将于明年交付，我将能够解析文物亚样本的内部结构。我将追踪遗迹内恒星的空间分布，以及它们是否像一些理论模型预测的那样以盘状结构旋转。我将建立一个遗迹光轮廓的动力学模型，以间接限制暗物质光晕的特征，其中嵌入了宇宙中最密集的物体。

Investigate Stellar Populations In Relics (INSPIRE) is a revolutionary way to understand the early assembly of the most massive galaxies in the Universe, giant ellipticals. This is very important since this family of objects contains more than half of the stars and the majority of the chemical elements in our Universe. Massive ellipticals are believed to form through a two-phase process. At the early times of the Universe's life, an intense, short-lived star formation episode creates compact and massive objects ("red nuggets"). Then, during a second, more time-extended phase, red nuggets merge with other galaxies or gas falls into them and forms new stars. This causes a dramatic growth in size and transforms red nuggets into the massive, giant elliptical galaxies we observe today. Unfortunately, in local ellipticals this secondary "accreted" material contaminates the "pristine" component that encodes the information about the first phases of the mass assembly. This irremediably prevents us from investigating on the very early stages of structure formation in the Universe. Luckily, some red nuggets do not coalesce with any other structure in their lifetime and so continue on their isolated path over cosmic time without increasing in size or, importantly, without changing their stellar content. These lonely red nuggets are up to 6 times smaller in size and 100 times denser than local ellipticals. They are frozen in time and are therefore called "relics" of the ancient Universe; studying them is akin to an archaeologist learning from dinosaur fossils. Relics contain the oldest stars and hence have the potential to unlock our understanding of the very early formation of structures within our Universe. But how many relics exist at each epoch? How could they passively evolve through cosmic time without experiencing any interaction with other systems? And in which kind of environment are they preferentially found? These questions are at the core of my successful research proposal, which uses the forefront facilities of the European Southern Observatory. From high-quality spectra already available on the largest sample of ultra-compact massive galaxies, I will measure their ages to confirm them as relics as old as the Universe. I will fully characterise the stars in these systems, to reveal how relics originally formed and how they have changed since, if at all.Since relics are the "seeds" of local giant ellipticals, my investigation will revolutionise our understanding of the processes driving the initial assembly of the most massive galaxies in the present-day Universe. Matching the INSPIRE data to data from publicly available wide field sky surveys, I will be able study in detail the environment in which relics are preferentially found. This is crucial to understanding how the densest and most compact objects in the Universe form and how they could evolve into local ellipticals. I will also compare my observational results with computer simulations of the entire Universe. The number of relics at each epoch and their characteristics predicted by simulations depend on the ingredients that they use to reproduce the size growth of galaxies (e.g. the number of interactions with other objects that a given galaxy undergoes). Finally, thanks to new imaging and spectroscopy data with the highest spatial resolution reachable from the ground, which will be delivered next year, I will be able to resolve the internal structure of a sub-sample of relics. I will trace the spatial distribution of the stars within the relics and whether they rotate in a disk-like structure, as predicted by some theoretical models. I will build a dynamical model of relics' light profiles, in order to indirectly constrain the characteristics of the dark matter halos in which the densest objects in the Universe are embedded.