Quantifying mass substructure in early-type galaxies

Promotie: mw. S. Vegetti, 14.45 uur, Academiegebouw, Broerstraat 5, Groningen

Proefschrift: Quantifying mass substructure in early-type galaxies

Promotor(s): prof.dr. L.V.E. Koopmans

Faculteit: Wiskunde en Natuurwetenschappen

Contact: Simona Vegetti, e-mail: svegetti@gmail.com

Quantifying mass substructure in early-type galaxies

Measuring the Cold Dark Matter (CDM) substructure mass function represents a key test of the CDM paradigm and provides an important step forward in understanding the physical properties of dark matter. Because of the predicted large total mass-to-light ratio of these substructures, gravitational lensing provides a unique opportunity to detect them. In this Thesis I have presented a new adaptive-grid method that based on a Bayesian analysis of the surface brightness distribution of highly magnified Einstein rings and arcs allows to identify and precisely quantify mass substructure in gravitational lens galaxies. I have also developed a Bayesian formalism to statistically interpret mass substructure detections and obtain constraints on the major properties of galaxy subhaloes such as the dark matter mass fraction in subhaloes and the subhalo mass function. I then applied this technique to the analysis of the SLACS lens SDSSJ0946+1006, which has led to the discovery of a very high mass-to-light ratio satellite at redshift z=0.222. With the lens system SDSSJ120602.09+514229.5, having a luminous substructure, I showed that the method can indeed detect substructure in lens galaxies and measure important properties such as the substructure mass and tidal radius. Finally, I demonstrated that high-quality infrared images from Keck laser guide star adaptive optics observations are equally sensitive to substructure and, under certain conditions, can recover the main lens and the substructure parameters equally well as optical data sets from the Hubble Space Telescope ACS and NICMOS.