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

作为宇宙中最大的受引力约束的物体，星系团可以被视为宇宙探测器，以约束潜在的宇宙模型。此外，它们也代表了研究重子物理及其与结构形成相互作用的最佳实验室。特别是在x射线波段观测时，充满势阱的热扩散簇内气体（ICM）使我们能够推断出有关ICM本身的内在结构、动力学和进化状态以及热学和化学性质的有价值的信息。未来的x射线任务，如ASTRO-H和ATHENA，预计将提供关于ICM特性的非常详细的见解，到目前为止还没有达到极高的x射线光谱精度。此外，x射线eROSITA全天巡天以及各种当前和正在进行的巡天（如SPT， DES， EUCLID等）的后续任务将为我们提供大量的x射线探测星团的目录，极大地增加了尺度关系和宇宙演化研究的统计数据，以及基于星团的宇宙学研究。为了跟上观测改进的步伐，需要对数值流体模拟进行虚拟观测，它能够模拟非常大的宇宙体积，并具有描述重子成分的各种物理过程。这将使我们能够追求大规模结构和星系团的前沿研究，迄今为止尚未实现的精度。特别关注x射线观测，我们将采用一种新型的x射线光子模拟器PHOX，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。特别是利用这个工具，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，并预测未来x射线任务对这些特性的可探测性。这将允许，例如，约束尺度关系的分散，研究x射线观测之间的协方差，研究暗能量宇宙学对星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.