Zusammenfassung
We present results on the dust attenuation of galaxies at redshift $\sim3-6$
by studying the relationship between the UV spectral slope ($\beta_UV$)
and the infrared excess (IRX; $L_IR$/$L_UV$) using ALMA
far-infrared continuum observations. Our study is based on a sample of 67
massive, star-forming galaxies with a median mass of $M_\ast\sim
10^10.7\,M_ødot$ spanning a redshift range $z=2.6-3.7$ (median
$z=3.2$) that were observed with ALMA band-6. Both the individual ALMA
detections (41 sources) and stacks including all galaxies show the
IRX-$\beta_UV$ relationship at $z\sim3$ is mostly consistent with that of
local starburst galaxies on average. However, we find evidence for a large
dispersion around the mean relationship by up to $\pm0.5$ dex. Nevertheless,
the locally calibrated dust correction factors based on the IRX-$\beta_\rm
UV$ relation are on average applicable to main-sequence $z\sim3$ galaxies.
This does not appear to be the case at even higher redshifts, however. Using
public ALMA observations of $z\sim4-6$ galaxies we find evidence for a
significant evolution in the IRX-$\beta_UV$ and the IRX-$M_\ast$
relations beyond $z\sim3$ toward lower IRX values. We discuss several caveats
that could affect these results, including the assumed dust temperature. ALMA
observations of larger $z>3$ galaxy samples will be required to confirm this
intriguing redshift evolution.
Nutzer