I am an Einstein Postdoctoral Fellow in the X-ray Astronomy and Observational Cosmology group at SLAC / KIPAC / Stanford University. Before that I was a PhD student [1] and post-doc at University Observatory Munich and the Max Planck Institute for extraterrestrial Physics.

My main research interest is weak gravitational lensing. I use weak lensing to study large structures in the Universe, such as clusters of galaxies [2,3,4,5]. The census and evolution of these structures is interesting in its own right, but it can also give us a better understanding of two of the greatest mysteries of modern physics, dark matter and dark energy. I am co-coordinator of the weak lensing working group of the Dark Energy Survey, the leading weak lensing experiment to date, and have presented its first competitive cosmological constraints [6,7,8,9].

I have devised a new density split statistic to measure the full probability distribution function of the matter density field [10]. With the Dark Energy Survey, I have used those measurements for unprecedented tests of gravity and improved constraints on cosmology [11,12].

I have developed new statistical methods for weak lensing, especially for estimating and calibrating photometric redshifts [13,14]. I have worked on developing new ways of measuring shapes of faint background galaxies. In the course of this work, I also got interested in the correction of instrumental features [15] required for precision analyses. I have also done the actual data reduction and weak lensing analysis of a number of clusters of galaxies, among them the pictures you see on top of this page.

If you are a student and interested in getting involved in the next generation of gravitational lensing research: please contact me about opportunities for rotations / projects for visiting students / internships.