Black holes in an expanding universe and interaction betweend dark matter and dark energy

Abstract

Our current understanding of the history of the universe, built over an increasing amount of data from accurate measurements such as the CMB and supernovae distances, tells us that we are most likely living in a homogeneous and isotropic universe which is undergoing a phase of accelerated expansion. The ›Lambda-CDM model, our best fit to observations so far, is far from being a complete model from a theoretical point of view, given that it does not provide clues on the fundamental nature of its main constituents: dark matter and dark energy. When we draw our attention to smaller scales, the problems become worse. Lambda-›CDM does not include baryons properly, and we lack a reliable understanding of star formation and its feedback on expansion. Therefore, it is evident that studying how bound systems feel the expansion of the universe, starting from collapsing star-forming matter up to galaxy superclusters at recent times, is of vital importance for a better understanding of the cosmos. Describing a gravitationally bound system in an expanding universe in the frame-set of General Relativity is a century-old problem which has seen many attempts to find a solution. Despite its apparent simplicity, a full understanding of the mechanisms involved when general and realistic systems are considered has yet to be found. This can be seen, for instance, by taking a look at the vast and often contradictory literature on the oldest proposed models, which shows us that even the apparently simplest solutions are rich in structure and have a difficult interpretation. To attack these problems, we take as a starting point our previous works on black hole accretion and dark matter and dark energy models. As in these works, we will continue to analyze exact as well as numerical solutions to space-time geometry, the evolution of compact objects in these metrics and the behavior of the surrounding matter, from a vicinity to the object up to large distances, to verify the connection with cosmological behavior. The next step is to use the same methodology in the context of modified gravity theories and models for the dark sector originating from field theory, to extend studies to all applicable areas and to explore all the possibilities this method offers. (AU)