A Bayesian Approach to Gravitational Lens Model Selection

Strong gravitational lenses are unique cosmological probes. These produce multiple images of a single source. Whether a single galaxy, a group or a cluster, extracting cosmologically relevant information requires an accurate modeling of the lens mass distribution. A variety of models are available, nevertheless discrimination between them as primarily relied on the quality of fit without accounting for the size of the prior model parameter space. This is a problem of model selection that we address in the Bayesian statistics framework by evaluating Bayes’ factors. Using simple test cases, we show that the assumption of more complicate lens models may not be justified given the level of accuracy of the available data.