Dark-ages Reionization and Galaxy Formation Simulation -- XIX:
  Predictions of infrared excess and cosmic star formation rate density from UV
  observations
  We present a new analysis of high-redshift UV observations using a
semi-analytic galaxy formation model, and provide self-consistent predictions
of the infrared excess (IRX) -- $\beta$ relations and cosmic star formation
rate density. We combine the Charlot & Fall dust attenuation model with the
Meraxes semi-analytic model, and explore three different parametrisations for
the dust optical depths, linked to star formation rate, dust-to-gas ratio and
gas column density respectively. A Bayesian approach is employed to
statistically calibrate model free parameters including star formation
efficiency, mass loading factor, dust optical depths and reddening slope
directly against UV luminosity functions and colour-magnitude relations at z ~
4-7. The best-fit models show excellent agreement with the observations. We
calculate IRX using energy balance arguments, and find that the large intrinsic
scatter in the IRX -$\beta$ plane is driven by the specific star formation
rate. Additionally, the difference among the three dust models suggests a
factor of two systematic uncertainty in the dust-corrected star formation rate
when using the Meurer IRX - $\beta$ relation at z > 4.
