Characterising Dark Energy through supernovae
  Type Ia supernovae are a powerful cosmological probe, that gave the first
strong evidence that the expansion of the universe is accelerating. Here we
provide an overview of how supernovae can go further to reveal information
about what is causing the acceleration, be it dark energy or some modification
to our laws of gravity. We first summarise the many different approaches used
to explain or test the acceleration, including parametric models (like the
standard model, LambdaCDM), non-parametric models, dark fluid models such as
quintessence, and extensions to standard gravity. We also show how supernova
data can be used beyond the Hubble diagram, to give information on
gravitational lensing and peculiar velocities that can be used to distinguish
between models that predict the same expansion history. Finally, we review the
methods of statistical inference that are commonly used, making a point of
separating parameter estimation from model selection.
