  We investigate the dust properties and star-formation signature of galaxies
in the early universe by stacking 111227 objects in the recently released
COSMOS catalogue on maps at wavelengths bracketing the peak of warmed dust
emission. We find an elevated far-infrared luminosity density to redshift 8,
indicating abundant dust in the early universe. We further find an increase of
dust temperature with redshift, reaching 100 +- 12 K at z ~ 7, suggesting
either the presence of silicate rich dust originating from Population II stars,
or sources of heating beyond simply young hot stars. Lastly, we try to
understand how these objects have been missed in previous surveys, and how to
design observations to target them. All code, links to the data, and
instructions to reproduce this research in full are located at
https://github.com/marcoviero/simstack3/.
