Evolution of dust attenuation in star-forming galaxies with UV slope, stellar mass, and redshift out to z 5
Abstract
Aims. We derive a dependence of the IRX on UV slope β, stellar mass M, and redshift out to z 5, and establish consistent functional relations that can be used for correcting the UV/optical-selected galaxy samples for the effects of dust absorption. Methods. This work is based on a K-band selected sample of 105 star-forming galaxies detected in the UDS and COSMOS fields. Quiescent sources and known starbursts are removed, and the IR luminosities are established through stacking in FIR Herschel and JCMT maps. UV slopes are found from SED fits and stacked IRX values are derived by taking the median of individual IRX measurements in bins of β, M and redshift. Results. While our best-fit IRX-β relation is consistent with a Calzetti-like attenuation curve at β -1, at bluer values the IRX seems to increase with redshift due to different mass-completeness limits imposed. When deriving the IRX-β relation in stellar-mass bins, a systematic trend is found, where the effective slope of the attenuation law becomes progressively shallower with increasing mass. We incorporate this into the IRX-β relation through the slope of the underlying reddening law, dA1600/dβ, being a quadratic function of (M/ M). Expressing IRX as a function of the stellar mass we find a tight correlation, with IRX rising monotonically with mass but exhibiting a clear high-mass turnover at z 2-3, consistent with suppressed cold-gas accretion and dust growth in massive systems.