Dust Obscured Star Forming Galaxies in the Early Universe

TL;DR

This study uses the luetides" simulation to predict dust-obscured star formation in early galaxies ($z>8$), finding that most high-mass galaxies already have significant dust obscuration, with implications for future observations.

Contribution

First simulation-based prediction of dust obscured star formation in galaxies at $z>8$, aligning with some observations and guiding future sub-mm surveys.

Findings

90% of star formation in high-mass galaxies at $z=8$ is dust-obscured.

Predicted surface density of $z extgreater8$ sub-mm sources is below current survey detection limits.

Relationship between dust attenuation and stellar mass matches lower redshift observations.

Abstract

Motivated by recent observational constraints on dust reprocessed emission in star forming galaxies at $z\sim 6$ and above we use the very-large cosmological hydrodynamical simulation \bluetides\ to explore predictions for the amount of dust obscured star formation in the early Universe ($z>8$). \bluetides\ matches current observational constraints on both the UV luminosity function and galaxy stellar mass function and predicts that approximately $90\%$ of the star formation in high-mass ($M_{*}>10^{10}\,{\rm M_{\odot}}$) galaxies at $z=8$ is already obscured by dust. The relationship between dust attenuation and stellar mass predicted by \bluetides\ is consistent with that observed at lower redshift. However, observations of several individual objects at $z>6$ are discrepant with the predictions, though it is possible their uncertainties may have been underestimated. We find that the predicted surface density of $z\ge 8$ sub-mm sources is below that accessible to current {\em Herschel}, SCUBA-2, and ALMA sub-mm surveys. However, as ALMA continues to accrue additional surface area the population of $z>8$ dust-obscured galaxies may become accessible in the near future.