Research Interests of Joachim Wambsganss
Our main research fields are cosmological exploration of quasars, galaxy clusters and dark matter on one hand, and the search for extrasolar planets on the other hand. Gravitational lensing - the deflection of light by gravity - is a very powerful tool for both research directions.
Searching for Extrasolar planets with MicrolensingBy very precisely measuring the lightcurve of a microlensed star in the galactic bulge, short time-scale deviations from a single-lens light curve can be detected, analysed and modelled. Most of these binary microlensing events are due to double stars; however, a small fraction of them are due to planetary systems. Microlensing searches for exoplanets are sensitive both to high and low mass planets. More than a dozen exoplanets have been discovered with microlensing so far. Microlensing is very well suited for statistical analyses of exoplanets. First results indicate that Neptune-like planets are common.
Quasar (Macro-)Lensing and MicrolensingGravitational lensing of distant quasars can be used for a number of cosmological questions. By measuring the time delay between the two (or more) quasar images, one can determine the Hubble constant. Uncorrelated short-timescale fluctuations in the various quasar images are an indication of microlensing, the action of individual stars in the lensing galaxy. Quasar Microlensing can be used as a ``microscope'' to exlore the innermost regions of the quasar engine.
Galaxy Clusters and Giant Luminous ArcsExamining and modelling giant arc systems produced by the lensing effect of galaxy clusters on background galaxies helps measuring the (luminous and dark) matter and the mass distribution of the lensing cluster. A statistical evaluationhelps us determine the cosmological model which best describes our universe.
Contact: J. Wambsganß