Gravity seminar - Sebastian Völkel Seminar

Abstract: The groundbreaking success in observing the gravitational wave emission from merging binary black hole and neutron star systems has opened a completely new window to observe the Universe. Among the outstanding opportunities and challenges are unprecedented studies of the strongest gravitational fields, which are produced by the most compact objects known today. This talk is about some of the emerging inverse problems. Here one starts from the characteristic gravitational wave emission and wants to reconstruct properties of the underlying compact object. Finding ourselves at the astonishing crossroad of neutron stars, black holes, and exotic compact objects, different types of problems appear. In this talk it is shown how semi-analytic methods are valuable tools to understand the governing equations and to extract information from the quasi-normal mode spectrum. By using WKB theory it is possible to address the inverse spectrum problem for non-rotating objects. Depending on the type of object, it is possible to constrain the effective perturbation potential, as well as parts of the metric and properties of the equation of state. An overview of some of the open problems is provided as well.