Numerical simulations of compact objects in general relativity and modified theories of gravity

在过去的10年里，爱因斯坦广义相对论中的黑洞和中子星的数值模拟取得了巨大的进步，这些方法现在被应用于天体物理、高能物理和新出现的引力波物理领域的各种场景。这个项目致力于在广义相对论的强场区域中计算中子星的模型，以及这一理论的推广，旨在解决当代物理学中的基本问题，最重要的是可以解释暗物质和暗能量问题的引力修正。特别是引力波物理学，将为社区提供前所未有的机会，用观测证据来应对这种变化。为此目的，至关重要的是在广义相对论的框架内对涉及致密物体的天体物理系统所期望的引力波信号及其可能的推广发展一个理论上的理解。特别关注的是所谓的标量-张量引力理论，在该理论中，除了公制自由度外，重力还受到一个或多个附加标量场的调节。要考虑的具体理论类别包括标准标量张量理论以及具有所谓筛选机制的更复杂的理论；所有这些理论目前都被考虑在Horndesky理论的保护伞下。所考虑的物理系统包括静态和动态中子星、包括超新星核心塌陷在内的引力塌缩和黑洞时空。在所有这些情况下，将研究引力波的形式以及系统的动力学，并将其与标准广义相对论类比进行比较，目的是确定修改后的引力理论可能的“确凿证据”。

The numerical modelling of black holes and neutron stars in Einstein's theory of general relativity has made enormous progress during the last 10 years and these methods are now applied to a variety of scenarios in astropysics, high-energy physics and the newly emerging field of gravitational-wave physics. This project is dedicated to the computational modelling of neutron stars in the strong-field regime of general relativity as well as generalizations of this theory designed to addressfundamental questions in contemporary physics, most importantly modifications of gravity that may explain the dark-matter and dark-energy problem. Gravitational-wave physics, in particular, will provide the community with unprecedented opportunities to confront such modifications with observational evidence. For this purpose it is vital to develop a theoretical understanding of the gravitational-wave signals expected from astrophysical systems involving compact objects in the framework of general relativity as well its possible generalizations. Particular focus will be on so-called scalar-tensor theories of gravity where, in addition to the metric degrees of freedom, gravity is mediated by one or more additional scalar fields. The specific classes of theories to be considered involve standard scalar-tensor theories as well as more complex theories with so-called screening mechanisms; all these theories are currently considered under the umbrella of Horndesky theories. The physical systems considered include static and dynamic neutron stars, gravitational collapse including supernova core collapse and black-hole spacetimes. In all these cases gravitational-wave forms as well as the systems' dynamics will be studied and compared with the standard-general-relativistic analogs with the goal to identify possible "smoking guns" of modified theories of gravity.