An optimal basis system for cosmology: data analysis and new parameterisation

Understand

We define an optimal basis system into which cosmological observables can be decomposed.

• The basis system can be optimised for a specific cosmological model or for an ensemble of models, even if based on drastically different physical assumptions.
• The projection coefficients derived from this basis system, the so-called features, provide a common parameterisation for studying and comparing different cosmological models independently of their physical construction.
• They can be used to directly compare different cosmologies and study their degeneracies in terms of a simple metric separation.