Modeling cosmological observations
The accelerated expansion of the Universe is the most surprising cosmological discovery in decades. It has inspired a newgeneration of ambitious surveys to determine the fundamental nature of this acceleration. I will introduce the observations used by today’s cosmologists, describe the modeling techniques used to connect these observations to fundamental physics, and present cosmology constraints from the Dark Energy Survey (DES Y1). This analysis constrains the composition and evolution of the Universe through joint modeling of galaxy clustering, galaxy-galaxy lensing, and cosmic shear. These three measurements, based on 20 million galaxies, yield consistent cosmological results, and in combination they provide some of the most stringent constraints on cosmological parameters. I will describe the validation of measurements and modeling from pixels to cosmology and give an outlook on the modeling and analysis challenges for future, much larger experiments that will map the position and shapes of billions of galaxies.