Black holes and active galactic nuclei as phenomenological test objects for a theory of quantum gravity

该项目的主要目标是研究环量子引力的经典大尺度极限，将后者理论与天体物理学联系起来，从而与观测联系起来。我们的目标是开发一种新的量子引力现象学场的方法和技术，在这种场中可以明确地计算特定的物理量。这样，我们就能够在色散关系中的一阶大尺度近似中研究星系外高能辐射（如起源于活动星系核的TeV耀斑）的量子引力修正。每一种引起色散的量子引力效应都非常小，但遥远天体物理源发出的辐射在到达我们之前要经过很长时间的传播，因此可能受到大量此类效应的影响，导致可观察到的结果。这些效应也可以用来解释在像TeV耀变体PKS 2155-304这样的非热辐射源的宽带光谱中所看到的能量通量的强烈的短时间变化。大尺度极限使我们能够找到与经典广义相对论黑洞解的对应关系。这些解不能只在广义相对论的框架内被理解，因为广义相对论在量子领域失效了。因此，使用量子引力理论来描述黑洞是必要的，它包含了广义相对论（圈量子引力）的所有原理。因此，我们将对黑洞物理学和天体物理现象学有更好的了解。

The main objective of the project is to investigate the classical large-scale limit of loop quantum gravity to connect the latter theory to astrophysics and hence to observations. We are aiming towards the development of methods and techniques for a new quantum gravitational phenomenological field, where specific physical quantities can explicitly be computed. In doing so, we are able to study quantum gravity corrections in a first order large-scale approximation in dispersion relations for extragalactic high-energy radiation like TeV flares originating in active galactic nuclei. Each of the dispersion-inducing quantum gravity effects is very small, but the radiation emitted by distant astrophysical sources travels for a very long time before reaching us and can therefore be affected by a large number of such effects leading to observable results. Those effects may also be used to explain the intense short-time variability of the energy flux seen in the broadband spectra of non-thermal radiation sources like the TeV blazar PKS 2155-304. The large-scale limit allows us to find a correspondence to the black hole solutions of classical general relativity. These solutions cannot be understood only in the framework of general relativity, because the theory breaks down in the quantum domain. Hence, the description of black holes using a theory of quantum gravity, which includes all the principles of general relativity (loop quantum gravity), is necessary. Therefore, we will obtain a better understanding of black hole physics as well as of astrophysical phenomenology.