Speaker: Katrin Heitmann (LANL)
Understanding the origin of the accelerated expansion of the Universe poses one of the greatest challenges in physics today. Lacking a compelling fundamental theory to test, observational efforts are targeted at better characterizing the underlying cause. If a new form of mass-energy, dark energy, is driving the acceleration, the redshift evolution of the equation of state parameter w(z) will hold essential clues as to its origin. In this talk I will discuss the challenges posed by the reconstruction of the dark energy equation of state from observational data. I will present a new nonparametric reconstruction method for w(z) based on Gaussian Process models. This method aims to reliably capture nontrivial behavior of w(z) and provide controlled error bounds. I will explain and demonstrate the method by applying it to different sets of simulated supernova data and show results for the continuous history of w out to redshift z=1.5 obtained from currently available data.