Black holes and trapped surfaces

Sammanfattning: The study of black holes is an important part of general relativity. However, the very definition of black holes is not completely satisfactory. Alternative definitions are based on the concept of trapped surfaces. This licentiate thesis is based on work with the aim to better understand the behaviour of such trapped surfaces.The standard definition of a black hole and specific examples are reviewed, as well as the definition of trapped surfaces, various horizons related to trapped surfaces, and the trapping boundary. This serves as an introduction to two published papers. The first paper provides an exact model of a marginally trapped tube making a sudden jump outwards as matter is falling into the black hole. The second paper concerns the question of the location of the trapping boundary in the Oppenheimer-Snyder black hole.