Studying the dynamical and thermal structure of the hot gaseous component in galaxy clusters by means of unprecedentedly detailed synthetic observations of advanced cosmological, hydrodynamical simulations

作为宇宙中最大的引力束缚物体，星系团可以被视为约束底层宇宙学模型的宇宙学探测器。此外，它们也是研究重子物理及其与结构形成相互作用的最佳实验室。特别是当在X射线波长下观察时，热的弥散星系团内气体(ICM)充满了它们的势能，使我们能够推断出关于ICM本身的内在结构、动力学和演化状态以及热和化学性质的有价值的信息。未来的X射线任务，如ASTRO-H和雅典娜，预计将提供对ICM特性的非常详细的见解，目前为止还没有达到非常高的X射线光谱精度。此外，X射线eROSITA全天观测以及各种当前和正在进行的观测(如SPT、DES、Euclid等)的后续任务，将为我们提供大量的X射线探测星系团，极大地增加对标度关系和宇宙演化的研究以及基于星系团的宇宙学研究的统计数据。为了跟上观测改进的步伐，需要数值流体模拟的虚拟观测，它能够模拟具有描述重子分量的各种物理过程的非常大的宇宙体积。这将使我们能够以迄今尚未完成的精度对大尺度结构和星系团进行前沿研究。为了特别关注X射线观测，我们将使用一种新型的X射线光子模拟器PHOX，它能够有效地从巨大和高分辨率的模拟输出中生成合成观测。特别是利用这一工具，我们建议研究模拟星系团的X射线发射，以便深入研究ICM的速度场和热力学结构，并对这些性质在即将到来的X射线任务中的可探测性做出预测。例如，这将允许限制标度关系的散布，研究X射线可观测物之间的协方差，并研究暗能量宇宙学对星系团整体性质估计的影响。

Being the largest gravitationally-bound objects in the Universe, clusters can be treated as cosmological probes to constrain the underlying cosmological model. Additionally, they also represent optimal laboratories to study the baryonic physics and its interplay with structure formation.Especially when observed in at X-ray wavelength, the hot, diffuse intracluster gas (ICM) filling their potential well allows us to infer valuable information on the intrinsic structure, dynamical and evolutionary status, as well as on the thermal and chemical properties of the ICM itself. Future X-ray missions, such as ASTRO-H and ATHENA, are expected to provide very detailed insights into the properties of the ICM, with a very high precision in X-ray spectroscopy not yet reached so far. Moreover, the X-ray eROSITA all-sky survey and the follow-up missions of various current and ongoing surveys (like SPT, DES, EUCLID, etc.), will provide us with vast catalogs of X-ray detected clusters, increasing enormously the statistics for studies on scaling relations and cosmic evolution, and for cluster-based cosmological investigations.To keep the pace with observational improvements, virtual observations of numerical hydro-simulations are required, which are able to simulate very large cosmic volumes with a variety of physical processes describing the baryonic component. This will enable us to pursue forefront studies on large-scale structures and galaxy clusters, with a so-far unaccomplished accuracy. With special attention for X-ray observations, we will employ a novel X-ray photon simulator, PHOX, capable to efficiently generate synthetic observations from both huge and high-resolution simulation outputs. By means of this tool, in particular, we propose here to investigate the X-ray emission from simulated galaxy clusters, in order to deeply study the velocity field and thermo-dynamical structure of the ICM and make predictions on the detectability of these properties with the up-coming X-ray missions. This will permit, for instance, to constrain the scatter of scaling relations, study the covariance between X-ray observables and investigate the effects of Dark Energy cosmologies on the estimation of cluster global properties.