# Dark-ages Reionization and Galaxy Formation Simulation -- XIX: Predictions of infrared excess and cosmic star formation rate density from UV observations

## TL;DR

This study uses a semi-analytic galaxy formation model combined with UV observations to predict infrared excess and cosmic star formation rate density at high redshift, highlighting the impact of dust modeling and star formation activity.

## Contribution

It introduces a Bayesian calibration of dust and star formation parameters in a semi-analytic model, providing self-consistent IRX-$eta$ predictions aligned with observations.

## Key findings

- Large intrinsic scatter in IRX-$eta$ driven by specific star formation rate.
- Systematic uncertainty of a factor of two in dust-corrected star formation rates.
- Best-fit models agree well with UV luminosity functions and color-magnitude relations.

## Abstract

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.